[SunHELP] Mirroring root disks with SVM on Sol9

[David Strom]

Re the post below, I had the same thing happen.  I was used to 
DiskSuite (iirc, always a question since I have CRS - Can't Remember
Stuff), where one of two boot disks would keep running/boot.  I
found a doc on the Sun Blueprints archive for October 2002 
(see http://www.sun.com/solutions/blueprints/ check online archives)
on Configuring Boot Disks with Solaris Volume Manager Software.
Page 10 has a setting for /etc/system which will let the system boot
with one of two mirrors for the root disk in a two-disk system, where
you'd have exactly 50% of the state database replicas available.

The setting is:  set md:mirrored_root_flag=1  (in /etc/system).
YMMV, no guarantees express or implied by me.  There's a caveat about
possible problems with stale replicas, but I don't see any way
around using this setting if you want a 2-disk system to keep
running & be able to reboot, after one of the disks has failed.

I suggest anyone interested in this subject get & read that document.

HTH.

--
David Strom

-----Original Message-----
From: Rick von Richter [mailto:rickv at mwh.com]
Sent: Monday, August 18, 2003 5:40 PM
To: Sun Managers Mailing List
Subject: Solaris 9 and SDS/SVM


OK I have read the archives but no answer for my question.
Our standard install to this point has been a mirror of the OS disks 
using SDS.  The key point being that if you lost a disk you would still 
have 50% of your metadbs and it would still boot off the remaining disk.

On Solaris 9, SDS chokes.  So we tried using the newer SVM but found 
that its metadb requirement is 50% + 1 viable metadbs.  So upon reboot 
with one bad disk the system will boot into single user mode.  This is 
not too much of a problem with local systems, HOWEVER, a lot of our 
systems are remote X1s or V100s with two disks.  So if this happens we 
are dead in the water.
Is there a way around this?  Or, maybe is there some other (small) 
software that can mirror the OS disks?  BTW, Veritas is out of the
question.

TIAWS