Re: Database mirroring, again
2006-02-07 14:09:08
I in my last class (tsm 5.2) it was still an issue, one way around this
issue (if I'm not mistaken) is to configure dbpageshadow in the server
options.
Kind regards DBPAGEShadow
Otto Schakenbos
System Administrator
TEL: +49-7151/502 8468
FAX: +49-7151/502 8489
MOBILE: +49-172/7102715
E-MAIL: oschakenbos AT teleflex DOT com
Corporate IT Europe
Teleflex Holding GmbH
Fronackerstrasse 33-35
71332 Waiblingen
GERMANY
Leigh Reed wrote:
Mark
I totally agree with your logic and in any other environment, hardware
mirroring would be a given. However, a few years back, I was involved in
a database corruption scenario. An unscheduled outage took down a TSM
server. At the time, the database was H/W mirrored with battery backed
up cache. A partial page write occurred, that was mirrored to both
plexes. When bringing the system back up, TSM deemed the DB to corrupt
and a DB restore was required
The advice from IBM at the time, was that you should always use TSM s/w
mirroring with MIRRORWRITE Sequential. I have carried on adhering to
this through the years, however, I would be interested in hearing if
this is no longer the case and the "partial page write" scenario is no
longer an issue.
Leigh
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Mark Stapleton
Sent: 07 February 2006 14:22
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Database mirroring, again
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 02/06/2006
01:07:08 PM:
I know we've been over this, but times change, and technology changes.
Conventional Wisdom on this list has been that the best disk layout
for
your TSM Database is:
JBOD disks, Raw volumes, mirrored by TSM, with 2 dbvols per physical
volume.
One note about conventional wisdom: *always* mirror with hardware when
possible. Hardware mirroring is faster and more stable. (Hardware
anything--mirroring, compression, encryption, etc.--is almost always
faster and more stable.)
The only reason TSM ever contained dbvol and logvol mirroring abilities
was to accommodate the ADSM server port to Windows, which at the time
had
no mirroring capabilities.
--
Mark Stapleton (mark.stapleton AT usbank DOT com)
US Bank Backup and Recovery Management
Office 262.790.3190
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