back to article Avoiding x86 cuts iSCSI cost and watts

An iSCSI developer said it has bucked the trend towards using standard servers to power storage appliances, instead using specialist chips that it designed itself. The company, called iStor, claims that as a result, its latest iS512 subsystems not only out-perform rivals such as EMC, EqualLogic, Intransa and LeftHand, but they …

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Paris Hilton

Saturation point

"t can stream data out at over 1100MB/s (9Gbit/s), out-performing duplex 4Gbit/s Fibre Channel.

He said that with 10Gbit/s Ethernet adapters constrained by Windows to around 3.6Gbit/s, a single iS512 can saturate three servers."

So let me see if I get this right... if you use Windows, the available data rate of 10GbE is reduced by a third (more or less) which makes their solution 3 times better... so the moral of the story here is surely - 'don't use Windows on a 10 GbE pipe'

Hmm - I guess it just didn't sound as good to say

'He said that with 10Gbit/s Ethernet adapters constrained by Solaris [0] to around 10Gbit/s unbonded, a single iS512 can maybe almost saturate one server as long as that server only has a single adaptor and not several like they'd typically have.'

[0] Insert suitable OS of choice here

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Math and cost

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A basic 2TB system costs less than £7000, while a version with 3TB of SAS or 12TB of SATA would be around £11,000, Shepherd said. "SAS is still about three times the cost per MB of SATA, although the gap gets lower as you go up in capacity," he noted.

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Is that the new kind of math? 3TB of SAS vs 12TB of SATA, and yet he claims that SAS is still "about three times" the cost per MB of SATA. According to my math, 12TB divided by 3TB is four times the cost, not three. Then again, looking at New Egg, the cost difference is way more than that. 1TB SATA drive is around 330 USD ($0.32/MB), 147GB SAS drive is around $425 ($2.89/MB), which works out to be about 9 times the cost of the SATA drive (per MB).

So, £11,000 / 22,000 USD for 12TB of SATA? A 1TB drive costs around $330, so that's $3,960 for the storage itself. So that's $18,040 for the RAID adapters, trays, and server hardware? Can we say ripoff?

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Anonymous Coward

Not a windows issue

10GBe is not limited by windows per se the article is misleading it is more a function of the bandwidth of your pci/pcie/pcix bus. a 133mhz 64bit pci-x bus limits you to about 1GB/Sec good for gigabit but not 10. So a 10GB card is pointless on this system as the bus becomes your limiting factor. On PCIe you need an x4 slot to probably fully use a 10GB port. though it depends on some other factors

Heres a good explanation http://www.dell.com/content/topics/global.aspx/vectors/en/2004_pciexpress?c=us&l=en&s=corp

I had a lengthy argument on this point before when some of our admins bought a 10GB card and werent getting the throughput they were expecting.

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Stop

Bits and bytes are NOT interchangeable!

re: Not a windows issue

"I had a lengthy argument on this point before when some of our admins bought a 10GB card and werent getting the throughput they were expecting."

I hope you didn't use the same argument you used here. If you did, then the admins probably walked away saying to each other "What an idiot!" I can almost guarantee you that your admins did not buy a 10GB card. I can also almost guarantee that the reason they didn't achieve anywhere near the max throughput is because of other factors unrelated to the bus (such as the speed of the medium they were reading from [hard drive]).

This is where people reading a tech journal need to sit back and use their grey matter -- bandwidth is measured in two ways -- xbps and xB/sec. The first, such as a 10GbE card (10Gbps) is BITS -- a 10 Gigabit per second network card. The second, such as the PCI-X bus (1GB/sec) is BYTES -- a 64-bit 133MHz PCI-X bus has a peak transfer rate of 1 GigaByte per second.

So, while you are technically correct that even the 64-bit 133MHz PCI-X bus would not be able to fully utilize 10GbE, it WOULD be able to utilitize 8Gbps (eight gigabits per second). In order to fully utilize a 10GBE card (notice the capital "B", meaning 10 gigabytes per second Ethernet), you would need a PCIe x16 card using encoded data (80 Gbps).

Bits and bytes are NOT interchangeable!

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Chris C

[word excised by Reg moderator]

This is why nerds have a bad rep and why forums on the internet are full of useless flame wars.

I'm sure the previous poster knew that it was a 10 gigaBIT adaptor. Do you think you can resist the urge not to point out the obvious just to prove how knowledgable you might be in a particular field? [Sentence excised by Reg moderator].

HINT: Morons that think a 10gbps card is measured in gigaBYTES per second usually won't be able to argue the logic that bus and device speeds are a constraining factor in reaching theoretical speeds. Anonymous Coward is clearly not that stupid so who cares if he used capital GB or not.

peace, god bless

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Ok, NOW I'm curious

"[word excised by Reg moderator]"

I have to admit to a certain perverse curiosity as to just what level of language you have to use to get moderated here, considering some of what I've seen get posted.

This is where we need a big question mark icon.

-daniel

P.S. - A.C. probably just made a mistake, but some mistakes should be corrected. Not so much for the sake of the original poster, but for the rest of the audience.

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re: Aaron

Actually, if you read the AC's post, and then you read the document he linked to, it is clear that he does NOT understand the difference between measuring in bits and bytes.

"a 133mhz 64bit pci-x bus limits you to about 1GB/Sec good for gigabit but not 10. So a 10GB card is pointless on this system as the bus becomes your limiting factor."

That shows that he understands the bus to be measured in gigabytes per second, but he then goes on to say that 1 gigabyte per second is good for one gigabit per second but not for 10 gigabits per second. Saying a 1GB/sec bus limit isn't good for a 10GbE card is like saying 4GB of RAM isn't good because about 0.5GB will be inaccessible in a 32-bit OS (so say the motherboard manufacturers). Just because you don't reach the theoretical maximum doesn't mean that coming darn close "isn't good".

I didn't write that comment to "prove how knowledgeable [I] might be in a particular field". I wrote that comment because there is a huge difference between Gb and GB, and I've seen many people make that mistake because they don't understand there is a difference. Asking that people are careful to use the proper notation does not make me a nerd, nor does it give anyone a bad rep. Not using proper notation can lead to serious and expensive disasters (just ask NASA about that one). It's bad enough that inattention to detail breeds ignorance, as can be seen in countless New Egg reviews such as this one: "Very disappointed that I paid for a 750GB and only got a 699GB hard drive." Let's not breed further ignorance by misusing the notations for bits and bytes.

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i know the difference

and you said it yourself PCI-x cant saturate a 10gbe card your assuming you have no HBAs etc sharing the bandwidth and the medium... they didnt get the bandwidth they were expecting because they are the idiots thank you very much.... sorry i put 10GB instead of GBe ooops my bad for mistyping.

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Anonymous Coward

Protocol loss...

While I wouldn't want to stir up the bloody big row any further...

Protocol overhead and packet loss can reduce the useful data carried over networks by a significant amount, the rule of thumb is usually 10bits network : 1 byte of data, thus a 10Gb network link would (with that apparently enormous loss) only just saturate an 8Gb bus link assuming that most protocol processing is done on the card.

I would expect a short network in a datacentre to do better however...

BTW If a network card is sold claiming 10Gb and yet doesn't have a bus interface capable of that speed it's not a 10Gb card is it?

"[word excised by Reg moderator]"

I was amazed by some of the stuff we got away with in the fat bastard discussion yesterday.

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