There’s always a first time
Sometimes it is great and sometimes, not so great.

Advice to the SAN-lorn
I’m asking readers to help this gentleman with his first SAN. I’ll kick off with my take after his letter. He didn’t ask to be anonymous, but out of respect for his heartfelt plea for help, I won’t identify him.

Should there be anyone who has cause why this couple should not be united in marriage, they must speak now or forever hold their peace.

I’m buying a SAN. It’s to make our poor overloaded database server go a bit faster. We’re also going to store our growing archive of 30 million jpgs on it.

After spending what seems like the last 6 months reading white papers, I’ve decided to go for five shiny new Lefthand Networks HP DL320s nodes. 3 nodes have 12*15K SAS drives for the database, 2 nodes have 12*750GB drives for the storage.

We’re a small company, and this is by far our biggest purchase ever – we can’t afford to get it wrong!

Oh how I wish there was a bit more off-the-record chat about this stuff… It seems every word I’ve read in the past months has been written by a vendor. I’ve never read about a problem with anything. Do all SAN’s work perfectly all the time, or are there often problems? Has anyone ever been disappointed with their SAN purchase?

Anyway – my reasons for choosing the Lefthand stuff are:

  • (They claim) random IO performance scales linearly as you add nodes (e.g. 3 nodes = ~5,000 IO/s, 6 nodes = ~10,000 IO/sec, 9 nodes = ~15,000 IO/sec)
  • * Unlimited capacity scaling by adding nodes
  • * Snapshots, remote copy, easy management, thin provisioning etc.
  • * Low initial costs (~$25,000 per node) – When I say “low”, I guess I mean “almost impossibly high, but lower than the big players”.

Please uncle StorageMojo, am I doing the right thing? Maybe if you posted this on your most excellent blog, your readers might have some advice?

Readers, hear this man’s plea! Please respond in the comments.

The StorageMojo take
Dear USM, you appear to be suffering from anticipatory buyer’s remorse. I commend you. Far better to suffer it now than after your check has cleared. That said, all I’ve heard about LeftHand is that their stuff works well. It does seem a little pricey, though.

I can assure you that many people have been disappointed in their SAN purchases. How to ensure you aren’t the next one is the question. You are thinking about the future and the growth of you application, both good things. Here are some questions.

You didn’t detail how you decided that storage was the problem. I’ll assume you’ve looked at a faster server, more RAM and tuning the database. You don’t mention much about your workload. Thirty million jpegs sounds like a photo-sharing application. Depending on how big the average jpeg is and how visitors use the system, you might be more bandwidth limited than IOPS bound. Do you understand how much load GigE will handle? How much server overhead will be generated by the iSCSI protocol? Are you buying TOE-based HBAs?

StorageMojo readers, please comment. I’ll be interested to hear what you have to say myself.

PS: the subject line of his email was “Dear Uncle StorageMojo” – which got me started on the whole “advice to the lovelorn” theme.