ADSM-L

Re: mirrored DB

1996-05-29 10:33:33
Subject: Re: mirrored DB
From: "Andrew M. Raibeck" <araibeck AT VNET.IBM DOT COM>
Date: Wed, 29 May 1996 07:33:33 PDT
John O'Neall writes:

>Fortunately, I'm not in production.   Thanks for your help.  In the light
>of this experience, tho, I'm still wondering where the usefulness of
>mirroring is.  If I find out, I'll let you know.

The real issue shouldn't be the usefulness of mirroring. There's a whole
industry based on it (RAID DASD) that says it's useful.   :-)

Seriously, I am concerned that there is something wrong on your system, perhaps
with the installation of ADSM, or there is a problem with ADSM itself.
This is why I recommended opening a problem with your IBM support. To the best
of my knowledge we should be able to recover from the situation you describe
with mirroring in place.

I did a little test myself, this morning, albeit with the OS/2 ADSM server. I
set up a mirrored set of database and recovery log volumes. Then I shut down
the OS/2 ADSM server and deleted the primary copies of my log and database
volumes. When I tried to start ADSM up, it came up successfully, with the
primary database and recovery log volumes in "offline" status.

So does mirroring work? Yes... at least in my test case it did. This is why
I suspect the problem lies more in the system or ADSM itself rather than with
the design (and hence the usefulness) of mirroring.

Andy Raibeck
ADSM Level 2 Support
408-256-0130
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