* Posts by Peter Gathercole

2533 posts • joined 15 Jun 2007

Britain collects new naval tanker a mere 18 months late

Peter Gathercole
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@MakingBacon

I'll bite. I think the statement about the car not surviving is reasonable.

The velocity of the fuel is based on the aperture of the nozzle and the amount of fuel that would need to pass through it. Moving fuel to a ship is performed using multiple lines all of which will be wider than a car fuel nozzle. If you try to move the same amount of fuel through a narrower pipe, the velocity will have to be much higher (hence the Mach 2 figure).

Comparing this to water-jet cutters, they typically use similar velocity, and although they normally have an abrasive in them to cut steel, fuel tanks in Range Rovers are probably made from a poly-something plastic.

As a result, I would expect a Mach 2 liquid stream to be able to cut through the car's fuel pipe, tank, and almost certainly through other parts of the car.

And this is avoiding the simple factor that this amount of fuel moving at Mach 2 would have a huge amount of kinetic energy which would have to go somewhere if it were to go from Mach 2 to rest in a short distance. I estimate that ~100 liters of fuel (Range Rover TD6) would weigh only a little less that 100Kg. Mach 2 is about 686 meters per second, so it would have a total energy (E=m*V2) of 47MJ. This is a lot of energy to dissipate.

As a result, I would not expect the car to survive.

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Microsoft Germany says Windows 7 already unfit for business users

Peter Gathercole
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Re: WONTFIX in KDE

I call BS on this as well.

X11 has the concept of window hierarchy. Starting at the root window, which IIRC always has window ID 0, is is possible to traverse the complete hierarchy, obtaining the window ID, the name of the application and it's window name, it's colour depth, position and hints.

Find the xprop and xwininfo binaries, run them, and point each at a window. Everything that is printed has been obtained through the X11 properties of the window. kwin is acting as an X11 window manager, so automatically has access to all this information.

I don't know how this will be altered in Wayland or Mir, but X11 (either in it's MIT, XFree86 or X.org guise) has been the standard windowing framework on Linux and UNIX (the exceptions being very old Sun and Apollo systems [if you remember them - although not strictly UNIX], and Mac OSX) for a very long time.

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Solaris 12 disappears from Oracle's roadmap

Peter Gathercole
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Re: SPARC/Solaris more expensive? Not anymore! @AC

I think you are Kebabbert, and I claim my five pounds!

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Brilliant phishing attack probes sent mail, sends fake attachments

Peter Gathercole
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Re: Sigh. Not again.

I don't know whether it's still true, but a PDF effectively used to be encapsulated PostScript, which allows very flexible device independent formatting, including embedded fonts, bitmaps and vector drawing capabilities.

When it was first deployed, it used to be set up so that documents could be immutable, i.e. not changeable by the recipient, so that you could be sure that what you saw was what the creator wanted you to see.

Of course, that did not suit everybody, so now PDFs are as editable as any other document format, and can even be used to produce forms that can be filled in and returned as a PDF.

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Asteroid nearly gave Earth a new feature, two days after its discovery

Peter Gathercole
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Re: So close? Re:Vector

If I remember my A-Level and university maths, what a vector represents is dependent on the number of dimensions you're working in.

If you are working in one dimension, a vector and a scalar are the same thing. In two dimensions (the standard environment when you are learning vectors IIRC), a vector is normally described as a one by two array in a cartesian co-ordinate system, or a scalar and an angle in a polar co-ordinate system.

In three dimensions, a vector will be a one by three three array in cartesian, or a scalar and two angles in polar co-ordinate system.

I'm sure that some theoretical physicist or mathematician will point out that they work in more than three dimensions!

So the upshot of this is that if you are working in one dimension, taking the path of the asteroid as a dimensional frame of reference, the velocity, even if treating it as a vector can be considered the same as it's speed, and this is what most lay people will count as a velocity.

Of course, celestial mechanics is never that simple, and is normally in at least 4 dimensions.

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FM now stands for 'fleeting mortality' in Norway

Peter Gathercole
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Re: DAB+ @DrXym @John Brown re: mobile data

and I then followed this up with a statement indicating it was shifting the cost from the broadcaster to the listener, so I have already agreed with your point.

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Peter Gathercole
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Re: DAB+ @DrXym - Replacement kit

Your plan does not take into account the restricted spectrum that I mentioned during the transition. I still think it is unlikely that extra spectrum will be allocated during the switchover. Maybe Norway will, but I'm pretty certain that Ofcom in the UK won't.

You also assume that people are happy to replace functioning equipment after a number of years. I will and do operate kit until it breaks (and if I can, I fix it when it does break), so I expect a DAB radio to last me 10+ years (my oldest DAB radio is about 12 years now, and still functioning). Even at this age, I would be upset about being forced to replace it.

I know a significant number of people who objected to buying new TVs or set-top boxes in the UK when analog TV was switched off.

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Peter Gathercole
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Re: DAB+ @DrXym

I totally agree that DAB was rolled out in the UK too early, but it's always difficult difficult to change things once they're generally (if you can say this about DAB) adopted.

Switching to DAB+ will be disruptive and expensive for those people who have already forked out for kit, and will be disruptive because they will have to reduce the available channels for DAB while they transition to DAB+ (they're not going to allocate any more spectrum during the roll-out).

Even if they offer a subsidy on new kit, I'm a skinflint, and don't want to re-buy, even at a discount, replacements for the 5 DAB radios I already have.

Mind you, I don't listen to it much at the moment, because for the coverage for my current commute (the time I use DAB most) is very patchy.

But I think DAB is dying in the UK. Some of the channels I used to listen to have left DAB as a platform, because (I understand) the cost of operating a DAB station is of the order of a million pounds per year, whereas transmitting over the Internet is much lower, and if you can get DAB somewhere, you're probably also able to get reasonable mobile data service. This shifts the cost of a broadcast service from the provider to the listener. I object to this (did I say I was a skinflint).

I think that by the time they are prepared to suggest a switch to DAB+, there will be no appetite for any over-the-air digital broadcast radio service any more.

But I do believe that there is still a place for analogue radio. It's still the best coverage, the best in terms of battery consumption for mobile devices, and the most widely adopted. I also think that it has a place in civil defence, because in the case of some national emergency, the digital infrastructure will be one of the first things to be affected. Operating an FM (or even AM) service is within the reach of a reasonably competent tinkerer in electronics using readily scavenged components, whereas digital broadcasting requires much more sophisticated knowledge and infrastructure.

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Landmark EU ruling: Legality of UK's Investigatory Powers Act challenged

Peter Gathercole
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Re: But I thought we "took back control" @Richard

This original law was drafted before the referendum, when the government thought that they would remain in Europe, so they should have expected to have this type of battle on their hands.

As such, it's got sod all to do with the result of the referendum, and much more to do with the fact that Home Secretaries (and I include Ms. May in this category) think that they have valid reason to ride roughshod over the privacy of Her Majesties subjects. This is true what ever political colour they have been. Remember Wacky Jackie?

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It's round and wobbles, but madam, it's a mouse pad, not a floppy disk

Peter Gathercole
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Re: Poor instructions @Dave 126.

I've only looked at UK pressings under UK light, so they are for 50Hz.

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Peter Gathercole
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Re: Poor instructions

If you look at 45's during the era of auto-changers, you would see that many of them had a circular 'bump' track between the innermost grove and the label. This was there so that when they were stacked, they would 'lock' together, preventing the upper ones from slipping while being rotated through a stack of lower disks.

What was more interesting is that the number of the 'bumps' was such that when viewed under a bright mains filament light while spinning on the turntable, they should appear static (strobe effect) if the turntable was running at the right speed, but you had to look very hard.

I have a copy of Tommy by the Who, which was a two LP set, which had sides 1 and 4 on one disk, and 2 and 3 on the other. This was so that you could play sides 1 and 2 on an auto-changer, and then turn both disks over together as a sandwich to play sides 3 and 4.

Mind you, the weight of the records falling down the spindle, especially the heavier vinyl used in the '60s and '70s was such that I was always surprised that the turntable survived. I suspect that is why the BSR decks (at least) has spring suspension to absorb the impact, not for any audio isolation. My Grandmother also used to use the auto-changer on her PYE Stereogram (about the same size as a small sideboard) for shellac 78s which were really heavy.

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Christmas cheer for KCL staffers with gift of extra holiday after IT disaster

Peter Gathercole
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Re: Repeatable?

If the data was real-world observations, it's still science, but not repeatable unless you have a time machine.

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What’s next after hyperconvergence?

Peter Gathercole
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Joke

Back in the last century

We had infrastructure that had small numbers of large system that controlled their own resources, be it memory, CPU, storage, or networking, with software components optimizing the use of resource. It ran on hardware that had enhanced RAS capabilities, and was quit expensive. Call this Stage 1.

Since then, we've been through:

Stage 2. Multiple smaller systems, each controlling their own resources, but they were cheaper.

Stage 3. Rolling all storage for these multiple systems into centralized storage solutions to make storage more flexible

Stage 4. De-duplicating the storage systems, so that the multiple OS files (and really only these files) would not have multiple copies wastefully stored

Stage 5. Virtualising all these multiple systems onto larger servers 'to save money and reduce wasted CPU and memory through resource sharing, and putting it on expensive systems with enhanced RAS.

Stage 6. Replacing the SAN with software defined storage systems.

Stage 7. Moving your communication infrastructure into the virtualised environment.

Stage 8. Virtualising the software defined storage systems into the enhanced RAS systems

So where are we.

We will now have infrastructure that has small numbers of large system that control their own resources, be it memory, CPU, storage, and networking, with software components optimizing the use of resource. It runs on hardware that has enhanced RAS capabilities, and is quit expensive.

All we appear to have done is replaced the OS with a hypervisor, moving everything one rung up the ladder, and we now have the traditional OS fulfilling the same function as the application runtime environments.

The next step will be to replace the traditional OS with a minimal runtime (hmmm, is that what containerization is all about), and we will have reinvented the Mainframe!

I've added the joke icon to try to deflect all of those of you who will try to point out the difference in detail between mainframes and hyperconverged systems.

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systemd free Linux distro Devuan releases second beta

Peter Gathercole
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And remember...

He had form before systemd, in that he was responsible for the cluster-fuck that was Pulse Audio, which was only really fixed after he moved on, I understand.

That was also an over-arching package that tried to control everything audio wise. He tried to offset blame to the distro maintainers (particularly for Ubuntu), but I struggled with it for many years (main problem being resampling rates and buffer-underruns after suspend on IBM Thinkpads, leading to gaps in the audio) before it suddenly just worked after an update.

Back in the tail end of the noughties, I think that one issue pushed more curious people away from Linux than anything else!

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Peter Gathercole
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@Vincent

I don't doubt your longevity with UNIX. It's definitely longer than me (6th Edition, 1978), but I seriously doubt that you were using 7th Edition in 1975 (although I believe PDP-11/45 in this time scale).

Most of the V7 documentation is dated 1978, and the Levenez timeline dated 7th Edition to 1979, so unless you were working in Bell Labs, I suspect that you were using 5th or 6th Edition in 1975.

Sorry to nitpick.

I must admit it is the use of XML and the severe scope of systemd that I don't like, as to me, it makes the startup of Linux pretty opaque.

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UK.gov was warned of smart meter debacle by Cabinet Office in 2012

Peter Gathercole
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Re: Points from a briefing

Not just nuclear. All bio and fossil fuels are carbon stores (a carbon battery?) that can be re-charged over years and megania (is this a word? A thousand millennia? It should be!) respectively from an outside power source (the sun).

Unfortunately, all you're really doing is moving energy around (you never 'generate' energy - merely convert it from one form to another, including matter - E=mc2), and will continue doing this until the heat-death of the universe!

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Peter Gathercole
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Re: Just Say NO

Or alternatively, your meter is reaching it's end-of-life (they are only certified to be accurate for a fixed period of time) and needs to be replaced anyway.

If this is the case, and it were me, I'd want to make sure a direct equivalent of the existing meter is installed, not a smart-meter.

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Internet Archive preps Canadian safe haven to swerve Donald Trump

Peter Gathercole
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Re: Asimov ?

Unfortunately, with all the snooping going on, hiding in plain sight in Canada (Terminus) is not an option.

I favor the option of Dicksons "Final Encyclopedia", or possibly Hactar.

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Debian putting everything on the /usr

Peter Gathercole
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Re: Not new @Daggerchild

The process was under the control of the HMC (Hardware Management Console). It would create the file, execute it, and delete it, and if anything failed, the entire process failed.

I'm no stranger to doing exactly as you suggest (even using hex editors to hand-hack binaries) to move files in awkward locations to better ones, but in this case, there was no point where I could break into the process to alter the location it was trying to use.

I even had a jail-broken HMC, and worked through how the process worked. It was using a script on the read-only filesystem (so immutable, even by changing the file on the server serving it - there was some strangeness in the NFS implementation where changes on the server were not picked up on the client, something to do with it being read-only mount and having NFS caching enabled), so while I could reboot the server to pick up the changes, that negated being able to hot-swap the PCIe cards.

We did the work. I just wanted to have the process fixed, because I have what sometimes appears a perverse desire to see defects fixed, rather than working around them (especially as I had already worked through the issue, and could point to exactly where the defect was).

Must be something to do with me having worked in Level 2 AIX support for a number of years. I really don't like having to tell people who are supposed to be providing support to me how to do their job.

I'm a really awkward customer!

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Peter Gathercole
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Re: only thing I ask @Olius

The problem with PCs in general is that if you use the old DOS MBR partition system, you can only have 4 primary partitions, and everything else has to be in an extended partition in one of the primary partitions. This generally meant that Linux was installed in a single partition, as in a dual-boot system you could not guarantee that there was more than one partition available for filesystems.

On my laptop, I used to have a rarely used Windows 7 (32 bit) primary partition, two Ubuntu OS primary partitions (one my current use release, and the other either a previous or the next version of Ubuntu depending on where I was in evaluating the LTS releases), and an extended partition containing a /home filesystem and the swap space (plus any partition backups I wanted to keep).

When I got my latest 2nd user Thinkpad, I found that Windows used two primary partitions, adding a boot partition. I dropped one of the Ubuntu OS partitions, although I did reserve the space in the extended partition for it for future use.

I really need to think about migrating to Xenial Xerus, but I'm not 100% sure I can install Ubuntu in a secondary partition. Maybe I should just bite the bullet and do a dist-upgrade, but I am not comfortable clobbering my current daily use OS with no fallback.

Presumably, my next laptop will probably have a GPT, but that's no reason to replace my perfectly functional system.

Stupid PCs.

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Peter Gathercole
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Re: I don't like change

I think it was a matter of convention and knowledge. The install docs (V7 here, nroff source) for Bell Labs UNIX did not give very many hints about how to do it, and if all you did was to follow the docs with a single disk system, you would end up with a layout that probably left you with nowhere other than /usr to store user files (Sorry, I did have links to PDF formatted documents from the Lucent UNIX archive, but that appears to have disappeared - still, "groff -ms -T ascii filename" will make a reasonable attempt to format these for the screen).

On the first UNIX system I logged into in 1978 at Durham University, there was a separate /user filesystem which mapped to a complete RK05 disk pack (about 2.5MB per pack). / and /usr (and the swap partition) were on disk partitions on a separate RK05 disk pack. At this time in V6 and V7, disk partitions were compiled in to the disk driver (in the source), and IIRC, the default RK05 split was something like 25%, 60% and 15% for root, usr and swap.

Whilst I was there, the system admins. (mostly postgrad students) added a Plessey fixed disk that appeared as four RK05 disk packs, and allowed them to give ingres it's own filesystem. This happened at the same time that V7 was installed on the system, over Summer vacation in 1979.

When I installed my first UNIX system (1982, again V6 and later V7 UNIX), I kept a similar convention. although I had two 32MB CDC SMD disks to play with, configured as odd sized RP03 disks, and I split each of the disks up as either four quarter disks, 2 half disks or one complete disk - don't use overlapping disk partitions! (again in the device driver source of V7 UNIX). It was a very involved process getting UNIX onto these non-standard geometry disks, but that's a tale for another day.

During this time, I also had access to an Ultrix system which user /u01, /uo2 etc (BSD convention).

When I worked at AT&T (1986-1989), they also used the /u01, /u02... convention for user filesystems.

Following that, I've always had a /home filesystem for user files.

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Peter Gathercole
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Re: I don't like change

I've been working with UNIX for 38 years (Bell Labs V6 onwards), and while I don't disagree with you, /usr has never been used for user files in my experience in all that time.I think I read in one of the histories of UNIX that it might have been used like this on the earliest PDP 8 releases (before my time), before they moved to PDP 11.

What was common was to actually have a /user filesystem in addition to /usr, although a convention adopted from BSD I think often had /u01, /u02 etc for user files.

IIRC, Sun introduced the concept of /home.

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Peter Gathercole
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Not new

Sun introduced a filesystem layout back in the 80's with SunOS 2 (I think), where /usr was a largely imutable filesystem.

What this allowed was the /usr filesystem of a system serving diskless clients to share it's own /usr filesystem with the clients.

If anybody cares to remember, the diskless client model meant that Sun 2, 3 and 4 workstations could just be CPU, memory, display and network, with no local persistent storage. Back when SCSI disks were very expensive, this allowed you to centralise the cost in a large server, and keep the cost of the workstations down.

The model was that all filesystems were mounted over NFS, with /, and /var (a new filesystem in this model) mounted (IIRC - myy memory could be faulty and confused by the differences between the Sun and IBM models) from /export/root/clientname and /export/var/clientname on the server as read-write filesystems, and /usr, (and later /usr/share) mounted read-only, served either from the /usr and /usr/share if the clients ran the same architecture and OS level, or from some other location which mirrored /usr if the clients ran a different version (this allowed SPARC architecture systems to be served from Motorola ones, or vice-versa).

Directories such as /etc, /var/adm, /usr/spool, /usr/tmp, which would have been on read-only or read-mostly became symlinks into /var (which was unique to each client as it was mounted from a different directory on the server).

Other vendors including IBM and Digital adopted very similar layouts for clusters of diskless clients. With IBM in 1991, it appeared with AIX 3.2 (and refined in 3.2.5). The filesystem layout meant that no machine should really write into /usr except during an upgrade, containing any variable files into /var. Unfortunately, many people (including IBM software developers) forgot this, and over the years, software expected to be able to write into directories below /usr.

Interestingly, the IBM 9125-F2C, aka Power7 775, supercomputer running AIX reintroduced the concept of diskless clients in 2011. The filesystem layout was modified slightly, with the concept of a statefull read-only NFS filesystem (STNFS), which allowed changes to the read-only filesystem to be either cached in memory for the duration of the OS run (a bit like a filesystem Union), or files/directories to be point-to-point mounted over entities on the read-only filesystem into a read-write filesystem.

/ became a STNFS read only mount, /usr was a read-only filesystem, and /var was a read-write mount off of an NFS server. /tmp was left on the / filesystem, meaning files were lost on a reboot, and also that writing lots of files into /tmp reduced the amount of RAM the node had!

Work related filesystems were mounted over GPFS for performance (NFS was just too slow), although any paging did actually work over NFS (obviously, paging was a major no-no for these performance optimised machines, but we could not get AIX to run without a paging space).

Unfortunately, as I found out, the hot-swap process for adapters, run over RMC from the HMC (Hardware Management Console) had a habit of trying to construct scripts in /usr/adm/ras (on the read-only part of the file tree) to execute to enable the swap, and as a result, we were unable to hot-swap adapters, which caused problems on more than one occasion. I did raise a PMR with support/development, but had trouble arguing the problem through, as the systems were so niche, that the support droids could not understand the problem.

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Hyperconvergence 101: More than a neatly packaged box of tricks

Peter Gathercole
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I think I must have a diffrent view of "simplicity"

In my view, a server is a real server, a network switch is a real network switch, and a storage subsystem is a real storage subsystem. That's simple (even more so if the storage is local to the server as SDS systems appear to be moving back to).

You get to think about them one at a time, and to scale, you just buy a bigger one of whatever has run out of steam!

I appreciate that the hardware landscape is simple with hyper-converged systems, but the software installation is not! (and I speak as someone who has used LPARd systems with hypervisors and visualized networks for over 10 years).

I've often thought one of the real reasons why it's caught on is because it allows the PC vendors to sell ever larger, higher margin systems (rather than cheaper, smaller individual systems) on the promise of overall reduced overall costs or energy consumption. I would love someone to publish a real world study that actually measures these savings.

You also get to suffer the problem of taking a large part of your infrastructure out of service, because you've got to replace a memory DIMM, processor, or other significant part of your hyperconverged system that is running everything.

Oh, wait. You need to invest in workload mobility products to overcome that problem!

$$$$<kerching>$$$$

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Irish eyes are crying: Tens of thousands of broadband modems wide open to hijacking

Peter Gathercole
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Re: "except for IP addresses" @Doctor Syntax

Please think about what you said for a second or two. You've been around here long enough to know the problem with what you've said.

Port 7547 is not a reserved port, and is in the ephemeral port range, so it is not beyond the bounds of possibility that it could legitimately be used by some other piece of software.

Just blocking it could have unpredictable effects.

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Peter Gathercole
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Re: "except for IP addresses" @Symon

IP Spoofing. Not really applicable.

There are two ways IP spoofing can have an effect. One is only possible if you are on the same physical network and subnet as the system you're trying to attack, and the other is if you are not trying to open a bi-directional session (normally only if you are attempting a DDoS packet flood or reflection attack, where you don't need any return packets).

In theory, I suppose it could work if you were physically on the same network as the system you're masquerading as, and could knock the management server off the net, or subvert the ARP cache on the router, but if a hacker has physical access to your ISPs infrastructure, then you're probably screwed anyway!

Anything else uses the source IP address in any packet as the destination for return packets, so they get routed to the systems you're masquerading as, not you (this is the reason it works in the same subnet, because there's no routing involved). So you never see any return packets, and thus cannot set up any TCP service as the initial handshake won't work.

One last thought. You could try source-routing the packets, but most routers don't allow this anymore.

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Kids' Hour of Code turns into a giant corporate infomercial for kids

Peter Gathercole
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Re: Child labor? @Chris King

It was really exciting to see Sarah Jane return to Dr Who in this story.

Elizabeth Sladen, RIP.

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Peter Gathercole
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Re: Duh - coding on pencil and paper @Steve Davies

You were lucky to have a punching service. I had to punch my own cards in my first job!

Still had to use coding forms, because there was one punch machine shared between four programmers and two Systems Analysts (whatever happened to that job role?), and we weren't allowed to write the program while we were at the card punch.

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Peter Gathercole
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Re: Minecraft as a way to force Win 10 in education

One of my (now grown up) kids says that the reason why Minecraft makes *any* computer crawl is because it does not use the GPU efficiently (or even much beyond a basic frame buffer if I understood what he was saying), and uses the CPU to render into a pixmap.

He once had an interesting hobby of capturing the most extreme way of making it grind to a halt, and then posting the videos on YouTube.

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KCL out(r)age continues: Two weeks TITSUP, two weeks to go

Peter Gathercole
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Re: Ah... so...

RS232 did not need termination.

It's possible that if you were attempting to drive it further than the stated maximum distances, you could find matching the impedance would help, but within spec, it was just point-to-point without termination.

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A cardboard desk? I won’t stand for it (actually I will)

Peter Gathercole
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More testing needed

It seems a little lacking in foresight just leaving the surface as untreated cardboard .

Why don't they at least put a shiny, moderately coffee proof surface on it (especially as a result of the 'drawback').

We need a long term test! I think Dabbsy should actually use it, and report monthly on how it is faring with regard to cup rings, grease stains, wear from mice (strangely missing from his desk) and keyboard legs.

Oh, and the use of it to support virgins, if only one at a time.

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Six on capacitor charges

Peter Gathercole
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Re: @DaLo

I recently spent some time learning how modern transformer-less switch-mode power supplies actually operate (thanks BOLTR on youtube), and I've changed my mind about how many of the capacitors are on 24x7 in the power supply.

It is quite clear that there are some that don't, but most power supplies in devices with standby mode nowadays appear to use a basic bridge rectifier and some high quality capacitors, and then feed the barely smoothed 120/240V DC into switched MosFets and smoothing capacitors/voltage regulators to act as voltage converters. The result is that when the device is in standby, most of the caps on the LT side of the MosFets are actually not powered up at all.

Of course, the switching control circuits are powered all the time, as are the first stage smoothing capacitors on the HT side, but this somewhat reduces the need for over-spec'd devices that will run for 100,000s of hours.

I'm not denying that capacitors fail, but I wonder what the statistical variance is on the MTBF figures for the cheapest Chinese capacitors actually is. I suspect this is more likely to cause early failures rather than devices that get close to the MTBF.

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Peter Gathercole
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@DaLo

Some time ago, I made a similar point, but was told by someone on the forums that the MTBF is based on the device being used at it's maximum voltage and temperature rating.

I was told that if you over-specify the capacitor, for example use ones rated at 105 Centigrade and 1000V for a instance that was room temperature plus and 230V, the MTBF would be exceeded many times.

Of course, what that probably means is that the original designers over-specify the devices, and during the production planning, devices only just exceeding the typical operating environment would be substituted as a cost saving measure.

I'm not really fussed, as it means that broken things with simple fixes can be bought and repaired for my own use, quite cheaply.

I often wonder just how many of the multitude of flat panel TV's that appear in our local recycling center are an easy fix.

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Accessories to crime: Facial recog defeated by wacky paper glasses

Peter Gathercole
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Re: Very useful @John Tserkezis

Interestingly, I recently had to get a renewal of my passport at very short notice, so I arranged a visit to the closest passport office.

When I was being interviewed (part of the quick application process), I commented about taking glasses off for the photograph, and the interviewer said that it is acceptable to wear glasses in the photograph, as long as the eyes could be clearly seen through the lenses (i.e. no dark glasses, small or half-frames that obscured the eyes themselves, or heavy reflections off the lenses).

I went back and read the passport application, and indeed, this is what it says.

But I'm sure that the jobs-worth post-office counter people who do the pre-check would not accept a photo with glasses, though. Last time I used the post-office passport checking service for one of my children, it took me three attempts to get photographs they would accept, and that was without glasses,

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What should the Red Arrows' new aircraft be?

Peter Gathercole
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Hawk T2

It's the only choice. The Red Arrows (and before them the Blue Diamonds) have always flown the RAF fast jet trainer, from the Hawker Hunter, Folland Gnat and the Hawk T1. It's done because of the lower cost and essential good handling (both necessary for a trainer), and because the Red Arrows are a part of the Central Flying School.

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Peter Gathercole
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Headmaster

Re: No F35 in the list? @Ralph

Um. We haven't had any battleships since 1960. The article quoted is about destroyers, although these are the largest combat ship in the RN until the Queen Elizabeth is commissioned. (Please note, HMS Ocean, Albion and Bulwark are not really combat ships, even though Ocean is the Fleet Flagship).

If you had said "warship" rather than "battleship", you might have been correct.

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Arch Linux: In a world of polish, DIY never felt so good

Peter Gathercole
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@AC

If you're going to post something like this, you really ought to post it under your name so that you can add the joke icon.

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Peter Gathercole
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Re: Nice distro, but.. @ Teiwaz

So use an LTS release.

Apply updates, yes, but you only have to do a dist-upgrade every four years or so, if you're prepared to skip a release.

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Ghost of DEC Alpha is why Windows is rubbish at file compression

Peter Gathercole
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Re: "chose not to serve" @Loud Speaker

That's a very interesting point, one I had not thought about, but the term CISC actually refers to a Complex Instruction Set Computer, and is defined by the number of instructions in the set, and the number of addressing modes that the instructions can use. I would say that the memory bandwidth savings were secondary, especially as most early computers processor and memory were synchronous.

I'm not sure that I totally agree with the definition of a PDP11 as a CISC (although it was certainly several generations before RISC was adopted), but the instruction set was quite small, and the number of addressing modes was not massive and exceptionally orthogonal, so it does not really fit in to the large instruction set many addressing modes definition of a CISC processor.

What made the PDP11 instruction set so small was the fact that the specialist instructions for accessing such things as the stack pointer and the program counter were actually just instances of the general register instructions, so were really just aliases for the other instructions (you actually did not get to appreciate this unless you started to look at the generated machine code). In addition, a number of the instructions only used 8 bits of the 16 bit word, which allowed the other 8 bits to be used as a byte offset to some of the indexing instructions (contributing to your point about reducing memory bandwidth).

One other feature that was often quoted, but was not true of most early RISC processors was that they execute a majority of their instructions in a single clock cycle. This is/was not actually part of the definition (unless you were from IBM who tried to redefine RISC as Reduced Instruction-cycle Set Computer or some similar nonsense), although it was an aspiration for the early RISC chip designers. Of course, now they are super-scalar, and overlap instructions in a single clock cycle and execution unit, that is irrelevant.

Nowadays, it's ironic that IBM POWER, one of the few remaining RISC processors on the market actually has a HUGE instruction set, and more addressing modes than you can shake a stick at, and also that the Intel "CISC" processors have RISC cores that are heavily microcoded!

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Peter Gathercole
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Re: "chose not to serve" @Oh Homer

CISC processors predated the adoption of the terms CISC and RISC. While you could say that, for example, a 6502 microprocessor was an early RISC processor, it was not really the case. The first processor that was really called a RISC processor was probably the Berkley RISC project (or maybe the Stanford MIPS project), which pretty much branded all previous processors as CISC, a term invented to allow differentiation.

As a result, you can't really claim any sort of design ethos for a CISC processor. Saving memory was a factor, but I don't really think that it was important, otherwise they would not have included 4 bit aligned BCD arithmetic instructions, because these wasted 3/8ths of the storage when storing decimal numbers.

You can say the converse. RISC processors, especially 64 bit processors often sacrificed memory efficiency to allow them to be clocked faster.

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Peter Gathercole
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byte, word and longword addressing

The earlier 'classic' Alpha processors (before EV56) did not support byte or word boundary aligned reads and writes from main memory. In order to read just a byte, it was necessary to read the entire long-word (32 bits), and then mask and shift the relevant bits from the long-word to get the individual byte. This can make the equivalent of a single load instruction from other architectures a sequence of a load, followed by a logical AND, followed by a shift operation, with some additional crap to determine the mask and the number of bits to shift.

But you have to remember that in the space of a single instruction on an x86 processor, an Alpha could probably be performing 4-6 instructions (just a guess, but most Alpha instructions executed in 1 or 2 clock cycles compared to 4 or more on x86, and they were clocked significantly faster than the Intel processors of the time - RISC vs. CISC).

Writing individual bytes was somewhat more complicated!

I was told that this also seriously hampered the way that X11 had to be ported, because many of the algorithms to manipulate pixmaps relied on reading and writing individual bytes on low colour depth pixmaps.

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America has one month to stop the FBI getting its global license to hack

Peter Gathercole
Silver badge
Joke

...previously hacked...

"But, Your Honor, Rule 41 says that we're allowed to break in to a previously hacked computer."

"Well, Mr FBI attorney, how do you know it was previously hacked?"

"That's simple to prove, Your Honor. We did it."

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Boffins coax non-superconductive stuff into dropping the 'non'

Peter Gathercole
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Headmaster

Grand mixture of temperature scales!

On top of the normal Centigrade/Celsius/Fahrenheit issues, the author has interspersed Kelvin, with both Kelvin and degrees Celsius converted into Fahrenheit, but no conversion from Celsius to Kelvin (I know, subtract 273.15 from the temperature in Celsius).

Technically correct, but confusing, especially as it is too easy to read K as in Kilo if you're not paying attention!

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Chinese electronics biz recalls webcams at heart of botnet DDoS woes

Peter Gathercole
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Re: What else they do then... @Peter Gathercole speaker cable

Yeah. Double insulated, as I said. It will work, but I miss the figure-of-eight cross section cable that I've always used.

Stupid really, that I should want to continue to use what I've used in the past.

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Peter Gathercole
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Re: Router Rules @Velv

That scheme (allowing DHCP to allocate addresses and hope that devices get the same addresses even when the lease expires) works until it doesn't, and then the consumer who didn't need to know how things work will be completely stuck when their port forwarding rules stop working.

Most DHCP servers on consumer grade routers allow you to reserve persistent IP addresses for certain MAC addresses. I don't see what is so difficult about setting up persistent addresses that will be fixed. After all, in order to set up port forwarding rules, one has to know something about IP and port addressing.

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Peter Gathercole
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Re: UPnP is a red herring in this thread @fidodogbreath

You have a point, but to be hacked, you need a vector to get to one of these devices.

If they are snug and secure behind a firewall (even one in a consumer grade DSL router), it will not be possible to even get to the device to attack it, regardless of how easy it is to hack. The reason why UPnP is being mentioned so much is that it is commonly used to expose the services of this type of device to the internet through a firewall.

Unless you can show that the devices were either on an un-firewalled network or directly connected to the Internet, you're going to have to come up with a way that the attacker could initially get to the device to hack it other than UPnP. Until you do, that is still going to be the most likely culprit.

Whether you like it or not, UPnP is a way for undisciplined devices to expose themselves. It's just a flawed service, and many knowledgeable people agree.

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Peter Gathercole
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Re: What else they do then... @A. S. A. C.

Probably WiFi connected room speakers, like the ones SONOS sell, and using UPnP to allow the music appliance to find them. Not my cup of tea, but whatever.

My speakers are connected to their amp via some old-fashioned 5A multi-strand lighting cable. Funny, I tried to buy some cable recently, and got the distinct impression that it was no longer available (at least as mains cable), I suspect because in the UK mains cable now needs to be double-insulated.

All I can get now appears to be specific 'speaker' cable, at stupid prices!

Progress?

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Peter Gathercole
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Re: Router Rules @AC

Totally agree re. uPNP and WPS, but if you want to set up the port forwarding rules yourself, you probably have to fix the IP addresses of the servers you want to port-forward to, either with manual IP addresses or fixed DHCP MAC-to-IP mappings.

Changing the password is a no-brainer that people do immediately anyway, isn't it? I even generate my own WiFi keys so as not to use the default, just in case it can be derived from some other information on the router, and hide the routers behind a Linux firewall and separate DSL modem.

The thing is, people I know ask why I do all this, when all they do is plug it all in, and press that little button on the router to register a device. "It's so much easier", they say.

If only I could directly implicate their network as being part of the botnet, I could show them the error of their ways...

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Bad news, Trump. NASty storage is pretty popular, too

Peter Gathercole
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GPFS...

...well more correctly IBM Spectrum Scale Storage, is a block based protocol (unless you're using the built in NFS bridge), putting the onus of working out where the storage for files is onto the client.

If you're taking about it working like a NAS, then you've probably come across it in it's SONAS storage appliance persona, not in it's GPFS client/server software defined storage persona.

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Smoking hole found on Mars where Schiaparelli lander, er, 'landed'

Peter Gathercole
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Re: It's WAR @John Brown

"EARTHMEN, WE ARE PEACEFUL BEINGS AND YOU HAVE TRIED TO DESTROY US, BUT YOU CANNOT SUCCEED. YOU AND YOUR PEOPLE WILL PAY FOR THIS ACT OF AGGRESSION. THIS IS THE VOICE OF THE MYSTERONS. WE KNOW THAT YOU CAN HEAR US, EARTHMEN. OUR REVENGE WILL BE SLOW BUT NONETHELESS EFFECTIVE. IT WILL MEAN THE ULTIMATE DESTRUCTION OF LIFE ON EARTH. IT WILL BE USELESS FOR YOU TO RESIST, FOR WE HAVE DISCOVERED THE SECRET OF REVERSING MATTER, AS YOU HAVE JUST WITNESSED. ONE OF YOU WILL BE UNDER OUR CONTROL. YOU WILL BE INSTRUMENTAL IN AVENGING THE MYSTERONS. OUR FIRST ACT OF RETALIATION WILL BE TO ASSASSINATE YOUR WORLD PRESIDENT."

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