Storage tiers

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Events have pushed us to give a serious look at cheaper storage solutions. What's got our attention most recently is HP's new LeftHand products. That's some nice looking kit, there. But there was an exchange there that really demonstrated how the storage market has changed in the last two years:

HP: What kind disk are you thinking of?
US: Oh, probably mid tier. 10K SAS would be good enough.
HP: Well, SAS only comes in 15K, and the next option down is 7.2K SATA. And really, the entire storage market is moving to SAS.

Note the lack of Fibre Channel drives. Those it seems are being depreciated. Two years ago the storage tier looked like this:
  1. SATA
  3. FC
Now the top end has been replaced.
  1. SATA
  2. SAS
  3. SSD
We don't have anything that requires SSD-levels of performance. Our VMWare stack could run quite happily on sufficient SAS drives.

Back in 2003 when we bought that EVA3000 for the new 6 node NetWare cluster, clustering required shared storage. In 2003, shared storage meant one of two things:
  1. SCSI and SCSI disks, if using 2 nodes.
  2. Fibre Channel and FC Disks if using more than 2 nodes.
With 6 nodes in the cluster, Fibre Channel was our only choice. So that's what we have. Here we are 6+ years later, and our I/O loads are very much mid-tier. We don't need HPC-level I/O ops. CPU on our EVA controllers rarely goes above 20%. Our I/O is significantly randomized, so SATA is no good. But we need a lot of it, so SSDs become prohibitive. Therefore SAS is what we should be using if we buy new.

Now if only we had some LTO drives to back it all up.

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What kind of software you are going to use?What file-system? What Raid 5 or 5+1?Is it for cluster environment?I believe HP are the best, if you are looking for redundancy and DDN are if you are looking for speed.All other, are in the middle of it.