How to make SQL Server 2008 redundant

I got several of 'em on HP hardware about a year ago for performance benchmarking testing, and some of the same things I said in the LeftHand VSA SAN question apply here too.

At the time, LeftHand's iSCSI multipathing wasn't truly active/active. Say you have:

• Four LeftHand servers with 2 1gb network cards each
• One volume on the SAN for your SQL Server data files
• One volume on the SAN for your SQL Server log files
• One SQL Server with four 1gb network cards dedicated to iSCSI

When you run a query on the SQL Server that accesses the data files, you will only get 1gb of read throughput despite the fact that you're using four network cards. The LeftHand devices (and indeed, all of the iSCSI SAN gear I've seen) will only send data from the SAN to one specific MAC address on the SQL Server.

You can work around this by:

• Using multiple data volumes and log volumes, and manually managing which path is the "primary" path for each back to the server. Even then, you're still only going to get 1gb of throughput for each data file, which restricts your backup performance, DBCC performance, etc.
• Using 10gb Ethernet.
• Using network teaming software that actually works. I've tried using a couple of vendors, and I haven't seen them overcome this problem yet.

If you need more than 1gb throughput, then until you hear from someone who's actually pulled it off, and can show it to you (not just say "oh yeah it works great on my l337 b0xx0r") then don't invest your money.

Fiber channel isn't necessarily different: it's just that you can easily get 4gb fiberoptic connections instead of 1gb Ethernet. You still have the same pathing challenges. I'm doing a presentation on this next week at IndyPASS, coincidentally - if you're in the area, swing by.

James Kehr with ORCS Web here. Thank you for considering our Virtual Dedicated Server package. The VDS package is an amazing deal and I am certain you will like the performance and features we offer.

As for your question, I am going to echo the comment above…it depends™. For the situation you describe 1 GB should do just fine. I peeked at the memory usage on a couple of our existing VDS servers with a similar setup and hit count and none of them are above 90% memory usage.

Just keep in mind that both SQL and IIS can get RAM hungry; plus you have the operating system memory footprint to think about. If your databases are relatively small, in the hundreds of megabytes total, and your site application does not use a ton of RAM you should be fine with 1 GB. On an very busy day you may get some lag during disk caching, but even then it shouldn’t be a significant performance bottleneck.

If you find that you need more RAM in the future we do offer upgrades at a very reasonable prices. In addition to RAM we offer disk space increases, additional vCPUs (virtual processors), enhanced monitoring and our popular Complete Care Package.

We do not publish upgrade prices for competitive reasons, but if you would like the current upgrade prices our sales team will gladly assist you.

Please let us know if you have any other questions.

James Kehr

System Administrator

ORCS Web, Inc.