back to article 3PAR developing united federation of clusters

3PAR is actively developing technology needed to federate its InServ clustered storage arrays together and provide a single pool of resources across the federation. 3PAR believes that there is a practical limit to the scaling on the number of nodes in a cluster, due to the risk of a node failure taking the entire cluster down. …

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Bronze badge

watch out

watch out for those klingons, they certainly don't want us forming a federation this soon!

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Grenade

RAID MP sounds familiar...

In fact, it sounds rather like NetApp's RAID-4 and RAID-DP technologies. Personally I thought that little blurb at the end was far more relevant for most IT professionals than the rest of the article.

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Go

@Colin_L

NetApp R4 and RDP is a Raid 4 tech that sticks parity onto dedicated disks - this causes them to run very 'hot' in a busy system and can cause slowdowns. The 3Par system sounds more like a tweak of Raid 6 to work on the 3Par 'chunklet' system (check their site for the exact details or see http://bit.ly/2YzQK5 ). This means that loads are still striped across all disks in the array which boosts performance.

Source(s): 3Par user

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Bronze badge

just for the checkbox

3PAR's architecture doesn't need RAID 6. They only came up with RAID 6 so they could put the check box on some customer's RFQs that say yes they do raid 6. Some customers are so dumb and narrow minded that t hey couldn't see past the fact that 3PAR didn't do RAID 6.

I'm sure at some point they can benefit from RAID 6, but probably not till you get to 5TB+ drives or something.

The distributed chunklet RAID based technology for the most part eliminates the chance of data loss during a double disk failure during a disk rebuild.

To put things in perspective, my array which is using about 121TB of raw storage(200 disks), has more than 80,000 individual RAID arrays on it. Disk rebuilds are upwards of 10x faster or more depending on the number of spindles in the array vs other systems, and have near zero performance impact while the rebuild is occurring. I simulated a drive failure in our early testing of the array by powering off a drive remotely.

The guy here who managed our previous array is constantly amazed that we've gone almost a year without a single disk failure(our array is 100% SATA, and the disks are *slammed* 24/7). The vibration absorbing drive sleds probably contribute a good chunk to that increase in reliability, I read an article here earlier in the year that talked about vibration being the #1 cause for disk failures.

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Stop

*NOT* just for the checkbox

If it's an ATA drive it's absolutely required these days, period end of story. I told both 3PAR & IBM (XIV product) to not talk to me about using ATA storage until you have that. It's not about how fast you do a rebuild, it's about how big of a rebuild you have to do. It's all about URE, I've got literally thousands of drives on the floor in the datacenter, you don't have 2x drives stop spinning, which is really where you care about how fast a rebuild is. A URE stands for "uncorrectable read error", which means that the drive thinks everything is fine and you make a request and it is unable to fulfil it. There is nothing the drive array can do about it, it's part of the drive. Goto Seagate, Hitachi, etc and look it up, most standard ATA drives have a drive manufacture failure rate of 10^14 (or ~12TB). So let's say I's using big raid5 groups 6+1 using 2TB drives (12TB usable). Statistically during a rebuild you are more likely to not to have some data loss. It might be a single 512byte bit, but that 512byte bit could include an oracle datafile, a critical bank transfer, or whitespace that you don't care about. Constant disk scrubbing minimizes this as it should find those failing sectors before the entire drive failure

I've personally had a raid5 drive failure + URE event in a raid event, only a single sector couldn't be rebuilt but it wrecked havoc and ultimately made ~30TB of other VTL data useless (the VTL app spread the writes around the array... very similar to 3PAR). So I'm not talking out my ass, not am I looking for simply a checkbox (note this was on 320GB pata drives so it was a few years ago).

I suggest you do some reading up, as it's a very real danger.

http://blogs.zdnet.com/storage/?p=164

http://storagemojo.com/2007/02/26/netapp-weighs-in-on-disks/

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