[sclug] RAID 1 adventure

[lug at assursys.co.uk]

On Fri, 20 Jun 2003, Neil Haughton wrote:

> Has anyone tried setting up Software Raid 1 on their Linux box?

Yup; been using Linux's md RAID implementation for about 8 months now, both
RAID0 (striping) and RAID1 (mirroring). No problems to speak of, though I do
wonder whether it'll correctly spot the failed drive if/when the time
comes... oh well...

> I have a spare hard drive the same size and speed as my current drive,
> and it strikes me as a good way to deploy it.  Some advice about gotcha's
> and so on will be appreciated.

- Always remember to shutdown properly, otherwise you'll have a long re-sync
  when the machine comes back up. This can be tweaked by echo'ing values to
  /proc/sys/dev/raid/speed_limit_<min|max>

- I built large RAID0 and RAID1 sets between pairs of partitions. This
  allows me to mix levels 0 and 1 using only two discs. I put the stuff I care
  about on the RAID1 set (/home, /usr/local, /var/spool, /var/lib/, ...) and
  the stuff I care less about on the RAID0 set (/usr, ...) using LVM to divvy
  up the space appropriately.

- Remember to tune the IDE bus using hdparm; DMA, IRQ unmasking, 32-bit IO
  (assuming your controller supports these options!)

- Put the drives on seperate channels, preferably not shared with any other
  devices.

> Neil Haughton

Please compose new messages to the list, rather than replying to the digest
mailing and quoting all of it. Thanks!

Best Regards,
Alex.
-- 
Alex Butcher      Brainbench MVP for Internet Security: www.brainbench.com
Bristol, UK                      Need reliable and secure network systems?
PGP/GnuPG ID:0x271fd950                         <http://www.assursys.com/>