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.

Our Dell rep sent over this link about Equilogic ISCSI SAN's, pricing is not yet posted but according to him, supposed to be very very interesting. Note that I don't own Dell stock, they just happen to be who we work with most of time.

Saw an plug for it from our sales rep yesterday, MD3000i. Starts at $7300 with just a couple drives, goes up to about $25k maxed out at 18TB. I've always considered the Powervault stuff pretty usable/reliable compared to the complexity of a SAN, but I see in the configuration that if you're going to connect to 8 or more servers it requires an on-site implementation (at no cost). Maybe not so simple anymore?

It does make me realize that I have a Dell centric view of the universe...which Im sure they appreciate. It saves a lot of time and money to standardize on a single vendor when you can, but you start to miss out on what everyone else is doing. I think the last time I looked at other storage options it was a cursory glance at a Sata Beast which looks like fun to buy. As a consultant it's nice to know the options, but usually I just give clients a broad outline of what hardware is needed and let them handle purchasing and install through the vendor of their choice.