[CentOS] raid 5 install

Mon Jul 1 16:35:09 UTC 2019
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On 2019-07-01 10:10, mark wrote:
> I haven't been following this thread closely, but some of them have left
> me puzzled.
> 1. Hardware RAID: other than Rocket RAID, who don't seem to support a card
> more than about 3 years (i used to have to update and rebuild the
> drivers), anything LSI based, which includes Dell PERC, have been pretty
> good. The newer models do even better at doing the right thing.
> 2. ZFS seems to be ok, though we were testing it with an Ubuntu system
> just a month or so ago. Note: ZFS with a zpoolZ2 - the equivalent of RAID
> 6, which we set up using the LSI card set to JBOD - took about 3 days and
> 8 hours for backing up a large project, while the same o/s, but with xfs
> on an LSI-hardware RAID 6, took about 10 hours less. Hardware RAID is
> faster.
> 3. Being in the middle of going through three days of hourly logs and the
> loghost reports, and other stuff, from the weekend (> 600 emails), I noted
> that we have something like 50 mdraids, and we've had very little trouble
> with them, almost all are either RAID 1 or RAID 6 (we may have a RAID 5
> left), except for the system that had a h/d fail, and another starting to
> through errors (I suspect the server itself...). The biggest issue for me
> is that when one fails, "identify" rarely works, which means use smartctl
> or MegaCli64 (or the lsi script) to find the s/n of the drive, then
> guess... and if that doesn't work, bring the system down to find the right
> bloody bad drive.

In my case I spend a bit of time before I roll out the system, so I know 
which physical drive (or which tray) the controller numbers with which 
number. They stay the same over the life of the system, those are just 
physical connections. Then when the controller tells drive number "N" 
failed, I know which tray to pull.


>  But... they rebuild, no problems.
> Oh, and I have my own workstation at home on a mdraid 1.
>      mark
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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