RAID Controllers

Question

This question is inspired by the recent Stackoverflow podcast where Joel and Jeff discussed the RAID controllers failing on a SO server and their experience with RAID. I was baffled by the negative experiences and observations as my experiences have been the complete opposite for years. I was curious what others have experienced out there.

• What brands of hardware based RAID solutions have worked for you? Why?
• What are your experiences? Why would you recommend against a RAID solution?
• Why would you use software over hardware based RAID?

Thanks!

Answer 1

First and foremost with anything mission-critical, pay attention to the hardware compatibility lists. Vendors test gear together to make sure it works. If something's not on the HCL, that does NOT mean they haven't tested it yet - that can also mean it was tested, and it doesn't work. This was the problem StackOverflow ran into - they used hardware that was not listed as compatible with each other, and it didn't work. Sure enough, after replacing the drives with ones on the HCL for that raid controller, it worked like a champ.

The same thing holds true with clustering, storage networking, and so on - the more intricate technology gets, the more ways it can break. Every time you cut corners, you're cutting uptime.

Answer 2

3ware (previously merged with AMCC, now merged with LSI)

Very nice, excellent Linux support (if that's important to you). I've been running an 8 drive raid set on a 9550 and for not much money I get some pretty impressive numbers out of it. Mine is SATA-II but now they're making cards for SAS as well.

Answer 3

My recommendation is to buy a popular, integrated, tested setup from somebody like Dell, HP, etc. Get it pre-configured the way you want it, make sure the drivers and firmware are up to date, and then don't touch it. If you pick something like a common 2U box with 6x drives in a RAID 10 or 5, you are buying something that has been put through lots of testing, and has been deployed by probably thousands of other people. For the most part, the bugs have been worked out.

If you try to hammer the parts together yourself, you are taking a huge risk.

But no matter what you do: update the firmware and drivers. That's the best simple piece of advice I can give anybody when it comes to RAID.

Answer 4

You usually can't pick brand of RAID since servers usually come with one or two different options for RAID. I had good experience with older generation of IBM servers (like the ones which Jeff had problems with :-) and various other from HP and Dell.

So, while I don't have any real suggestion about particular brand of RAID controllers, I would prefer to have hardware RAID in my box, even if I'm using software RAID on top of it because most RAID controllers also come with battery backed cache which speeds up write operations even when not using hardware RAID. So, pick RAID with biggest cache and you are ready to go!

YYMV, but I hope this will somewhat help.

Answer 5

Adaptec is the only one I buy now. I've had issues with other cards before. They may be fine now, but when you lose a RAID array, it'll scare you off of them for while!

Answer 6

Not a dup question, but some of it is already here: Software vs Hardware RAID

Answer 7

What brands of hardware based RAID solutions have worked for you? Why?

Promise Fasttrack - it was cheap and supported Novell server 3.11. It worked very, very well over a few dozen servers.

What are your experiences?

For some time I also used a raid (striped) on my workstation and it was a beautiful, beautiful thing. Applications opened instantly. Compiles were immediate. Windows started faster.

Unfortunately I didn't want to spend the money on a RAID 10 (mirror on stripe - don't use RAID 01) and I didn't like the additional failure point of a second hard drive (either one could fail and my system is dead). The cost wasn't worth the extra speed, and the reliability of the cheap solution was to costly if it failed, and posed a greater risk than a single hard drive.

Why would you recommend against a RAID solution?

Only for cost and power consumption purposes. I would also recommend generally against RAID 5 - drives are cheap enough that if you've decided you need RAID, then 10 is the way to go.

Why would you use software over hardware based RAID?

Check out the ongoing discussion: RAID - software vs. hardware

A VERY worthwhile take on RAID 5 and RAID 10 vs RAID 01 should be mandatory reading before using any RAID setup:

http://miracleas.com/BAARF/RAID5_versus_RAID10.txt

-Adam

Answer 8

Areca has a great portfolio of RAID cards.

I am using 2 16-port cards for around 3 years now and they performed and perfom flawlessly. They were at the time the only ones to support RAID 6 which allows 2 simultaneous drive failures. This helped tremendously with me getting enough sleep and stop worrying about data loss. Survived several drive failures in those years. It is amazing how often modern drives tend to fail.