OT: 3ware [was: Install CentOS 6 X86_64 …]
You totally jinxed them! You’ll probably have three of them fail in the next month. ;-)
I decided to do verifies once a month, instead of the default once a week. My thinking was that hitting all of every drive so frequently might be a wear factor, but periodic scrubs are still important; plus, for my larger arrays, having performance slightly degraded 1/7 of the time was not so desirable. So now I do 12 verifies a year instead of
52. I think the verify has picked up maybe two errors in ~10 years.
(It does sometimes expose when a drive is failing, which is handy.)
The LSI MegaRAID cards have their own scheduling, and I haven’t had time enough to read the manual to figure out how to set this (or indeed, even to figure out what the schedule is; the MegaRAID UI is much more arcane than the 3ware).
–keith
2 thoughts on - OT: 3ware [was: Install CentOS 6 X86_64 …]
Then you too manage to stick with reliable drives! Performance… well, I
have array verify scheduled to start 23:00 on Saturday… also, on newer controllers you can choose policy with highest priority for IO and lowest for rebuild etc. I’m kind of sceptical about extra wear to mechanical drives added by RAID check: my drives are always spinning full speed (no spin down crap, thank you), and heads are not touching the platters… So, I’m not certain there is extra wear. The only wear apart from bearings I
know about is when arm hits the stopper which only happens when you power off the drive, which not the case here too. What do I miss?
Valeri
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Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247
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I learned the “reliable drive” lesson the hard way, when I accidentally ordered, and then unwisely decided to use, crappy drives. Fortunately no data was ever lost, but the drives made a lot of extra work for me.
You may be 100% correct about wear. I have no actual evidence that extra verifies causes more wear than normal use.
For my largest arrays, even if I started at 23:00 on Saturday, it would still be going through much of Sunday. Plus I have other disk operations that occur overnight. The performance loss isn’t terrible during a verify, but I have noticed it enough that I prefer to avoid it happening so frequently.
I’ve heard quite a few horror stories from people who never did a scrub of their arrays. But I haven’t heard any from people who did scrubs less frequently than weekly. Has anyone? I’m genuinely curious; if there’s a justification for weekly scrubs that’s stronger than my fairly weak justifications for monthly, I’d switch back.
–keith