From: MacDonell, Dennis (DennisMacDonell@auslig.gov.au)
Date: Tue Feb 04 2003 - 00:38:38 EST
Hi,
I didn't realise it but it would appear that you can create a software raid5
(ie a stripe set with a parity check block) using lsm. The server I want to
set this up on is a DS20E with some smallish amount of disk around 200gb all
up. The OS is Tru64 V5.0A. I'm in the process of re-creating an lsm volume
that only had striping and was thinking that a raid5 volume might be the way
to go. From preliminary reading it would appear that one has to use volmake
and subdisks to arrive at raid5. Currently when I create a strip set I just
(a) setup a disk for lsm using "voldisksetup -i $DISK privlen=1024 nconfig=1
nlogs=1"
(b) initialize the diskgroup with "voldg init $DG $DISK", or
(c) add the disk to the diskgroup with "voldg -g $DG adddisk $DISK=$DISK"
(d) then use volassist the make the volume after working out how big the
thing is "volassist -g $DG make $VOL ${DGSIZE}k",
My idea is to have a suite of the same size disks, ie 36gb, or 72gb, and use
each disk as a separate column. My guess then is that all I have to do is
before (d) above do a "volprint -A" to find out what the plex and sub-disks
have been called by vold. Then use volmake instead of volassist to create a
raid5 layout using as the number of columns the number of disks. As for the
stripe width, I'm not sure what one should setup, by default it will select
16K, which I guess should be efficient.
Also it would appear that one should have a log plex. Not sure what is
involved there, are there any restrictions on the size of this plex, can one
just carve out a bit of disk space from somewhere on the system.
Would someone be kind enough to put me straight on how to set this up.
Dennis
This archive was generated by hypermail 2.1.7 : Sat Apr 12 2008 - 10:49:06 EDT