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Provisioning Storage

It's a rite of passage in our business that we have to learn the RAID levels, and I still enjoy the arguments about RAID-5 vs RAID-10, and it seems we still have to keep having the conversation about spindles vs space. But the world is changing with SAN's becoming very common, and many businesses now have a full time storage person, which brings us to the point of the post today.

Probably more than any other part of the business we're using to pushing hard for the hardware we need (or think we need) when it's time to buy. That's fair, because we probably demand more of the hardware than anyone else and don't have the luxury of scaling out like the web guys do. SAN's arent a miracle cure for performance, but the old rules aren't always the right rules for a SAN either.

Instead of demanding x drives configured in RAID x, what we should be doing is putting together a service level agreement (SLA) and sending it to our network team/storage team/SAN vendor, and in simple form it might look like this:

  • Require space provisioned as follows: Drive Z, 500g (data), Drive Y, 100g (logs), Drive X, 300g (backups)
  • Each drive specified must run on different physical drives so that if anyone one drive (letter) fails the others remain safe
  • Implement RAID 1, 5, or 10 for each of those drives.
  • Guarantee sustained IO rates as follows: Z:, 1000 IOPS, Y:, 250 IOPS, X:, 250 IOPS
  • Interface preferred is Fibre Channel, iSCSI is acceptable

Instead of telling them how to do it, we're telling them our requirements and letting them figure out best way to implement it (isn't that we want from people asking us for assistance?). We don't need to know or care that the storage is really a couple of cheap SATA drives set up in RAID 1 as long as we get our SLA. If they don't meet the SLA, well, someone has to fight that battle. If we didn't ask for enough, we revise the SLA based on recent operations and ask them to meet the new SLA.

Make them work for you, but let them figure out the solution!

Don't lose interest in storage entirely though, your next job may have you wearing more than one hat in an environment with no SAN, and then all that stuff you had to learn and maintain will pay off.


I'm Andy Warren, currently a SQL Server trainer with End to End Training. Over the past few years I've been a developer, DBA, and IT Director. I was one of the original founders of SQLServerCentral.com and helped grow that community from zero to about 300k members before deciding to move on to other ventures.


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