Re: Need advice on RAID5

<wwparks> wrote:

>We installed two databases using RAID 5 on a SPARC 1000 and SPARC 2000 and
>were very disappointed with the performance. The volumne managment software
>creats Files spanning three volumnes which was much slower than RAID 0 which
>spanned all volumes. So we switched back. I would recommend looking at
>mirroring with RAID 0.
>

That's the default for configuring raid 5 with veritas volume manager. It is slow. You can create a raid5 volume over more disks and get better performance. The manual does not tell you how, but here's what to do:
create a default small (10K) raid5 volume with vxassist or the gui.

stop the new volume

remove its plexes (all of them). This removes the subdisks as well.

create you own subdisks on as many disks as you like.

combine them into a plex

attach this to the default volume created at the start, set the lengths and intitalise the raid5.

it should be possible to do this without kludging the default, but its the only way to get a read policy of raid 5 because the doco and man pages are wrong.

this works! Exact details, mail me.
gedau_at_mim.com.au Received on Sat Oct 21 1995 - 00:00:00 CET