SUMMARY: Volume Manager RAID5

From: Goodson Alex A (
Date: Fri Apr 14 2000 - 02:24:25 CDT

The overwhelming opinion is to give RAID5 a miss and use 0 + 1, or if you've
got the latest version of VM 1 + 0 (thanks Jeff ).

However, this isn't really an option for us since we need as much available
disk space as possible.

It would appear that if you are going to use RAID5 you should use a log disk
because it is possible to get data corruption in the event of a disk
failure. This was strongly recommended by SUN.

The procedure to do this in vxva in order to avoid losing an entire disk to
the log is as follows.

Make sure that you've got 2.5 MB spare on a disk in your disk group that
you're not going to use for the RAID5 set.
Create the RAID5 set by selecting all the disks you want to include and
choose Basic Options - File System - Create - RAID5
Unselect the log subdisk option, click on the max size option and enter the
volume name and mount point. Click OK.

This will create (eventually) a RAID5 volume with no log disk. The next step
is to select the Volume and the disk which you want to use for the log and
choose Basic Options - Volume - Add log. This will create a 2.5MB log (much
better than the 18GB log you get if you add the log when you create the

If you want to mirror your log you simply create another log on a different
disk. You don't need to explicitly mirror it.

Using this method I was able to get a 51GB filesystem using 4 x 18GB disks
plus a small part of another disk for the log.

Many thanks to

Jeff Kennedy
Kyung Suk
Daniel Rowe
Chandra Kalle
Baurjan Ismagulov
SUN Support

This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:14:06 CDT