I'm in the 'belt - suspenders (braces) - safety pins - glue - duct tape'
crowd myself. I have my TSM database on a fiber-attached ESS; TSM
mirrors this to the same ESS in a different logical subsystem (ran out
of money -- couldn't get the second ESS). The TSM logs are also mirrored
on the same ESS to yet another pair of subsystems.
I've never noticed anything in the way of a performance issue -- but my
database is only using 71% of 20 GB.
Tom Kauffman
NIBCO, Inc
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Paul Fielding
Sent: Friday, April 08, 2005 1:54 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Question on SETUP
I'd be interested to know if anyone has done real performance testing
re:
using TSM mirroring with a RAIDed backend.
People on the list are raising valid reasons for using TSM mirroring on
top
of RAIDed disk (though I think that it's important for people to
understand
exactly *why* they are doing this and ensure that they've laid out the
disk
they're using appropriately - eg. mirroring to a bunch of files in the
same
FS is probably a bad idea).
The next question though, would be what sort of performance hit might
one
take in doing this? Obviously not a simple question as there are
factors
such as whether or not the disk being mirrored is same type, is the
mirrored
data going out the same scsi/fc wire, etc. That being said, if those
factors are considered and mostly mitigated, do people find anything
else in
this scenario that might cause a performance hit, or do things seem to
fly
along quite nicely?
regards,
Paul
----- Original Message -----
From: "Prather, Wanda" <Wanda.Prather AT JHUAPL DOT EDU>
To: <ADSM-L AT VM.MARIST DOT EDU>
Sent: Friday, April 08, 2005 12:21 PM
Subject: Re: [ADSM-L] Question on SETUP
> Yet another opinion:
>
> If you are running TSM HSM, that requires 24x7 availability. Then you
> should mirror both DB and logs.
>
> If you are NOT running TSM HSM, a lot of TSM installations can
actually
> afford to have TSM down a couple of hours.
> SO what I usually do, when I have the DB on a RAID device, is just to
> mirror the recovery log.
>
> That way, if you DO lose the DB due to some type of logical
corruption,
> you can always restore from your last DB backup, and roll forward from
> the log. So you lose no data, just some time.
>
> It's adequate protection, if you can afford the time.
>
> (That assumes you run in ROLLFORWARD mode, which you SHOULD be doing,
> and you are very religious about your DB backups, which you SHOULD
be!)
>
>
>
>
>
>
> -----Original Message-----
> From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf
Of
> Joerg Pohlmann
> Sent: Thursday, April 07, 2005 10:38 PM
> To: ADSM-L AT VM.MARIST DOT EDU
> Subject: Re: Question on SETUP
>
>
> Hi Paul. From bitter experience I have been saved by TSM mirroring on
> nicely protected disks. I have had complete filesystems clobbered as
> result of other hardware failures, nothing to do with the disks - have
> had
> filesystems damaged on AIX and also Windows. TSM mirroring is such a
> superb, inexpensive protection against these other failures that I
> always
> recommend TSM mirroring. It's also quite inexpensive give todays cost
of
> disk storage, including Shark. And yes, on a Shark I would create four
> filesystems (/tsmdb1 /tsmdb2 /tsmlog1 /tsmlog2 - Windows an D: E: F:
and
> G: drive) so that the 1s and 2s (or the E: and G: drive) are in
> different
> LSSs.
>
> And yes, I wear belt and suspenders.
>
> Joerg Pohlmann
> 604-535-0452
>
>
>
>
> Paul Fielding <paul AT FIELDING DOT CA>
> Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
> 2005-04-06 23:25
> Please respond to
> "ADSM: Dist Stor Manager"
>
>
> To
> ADSM-L AT VM.MARIST DOT EDU
> cc
>
> Subject
> Re: Question on SETUP
>
>
>
>
>
>
> I don't see the value in mirroring the db and logs if they're placed
on
> Shark disk. The purpose of TSM's mirroring is to provide disk
> redundancy
> in case of disk failure. However, the Shark provides it for you.
Why
> add
> the extra overhead of software mirroring when the hardware does a
> valiant
> job in the background. The Quck Start recommendation doesn't take into
> account that your disk is already protected...
>
> regards,
>
> Paul
>
> ----- Original Message -----
> From: "Jones, Eric J" <eric.j.jones AT LMCO DOT COM>
> To: <ADSM-L AT VM.MARIST DOT EDU>
> Sent: Wednesday, April 06, 2005 2:56 PM
> Subject: [ADSM-L] Question on SETUP
>
>
>> Good Afternoon.
>> I was asked to setup a new TSM server 5.2.2 on a AIX 5.2 server.
>> My question has to do with setting up the DB, LOG and DISKPOOL.
>> On our current servers which run the same O/S and TSM version the DB,
> LOG
>> and DISKPOOL are mirrored.
>> On the new system I'm setting up these are all going to reside on a
> IBM
>> SAN(SHARK) which is all RAID.
>> Is there any reason to mirror them since the mirror would be on the
> same
>> set of drives(space was already allocated on a LUN)?
>> I understand it's always good to mirror(protect DB, LOG, DISKPOOL)
but
> in
>> this case I'd have to mirror to the same set of disk since I was only
>> allocated a set of space to work. In the TSM class it also
> recommended
>> that you mirror for protection.
>> I'm in the middle of reading the "Quick Start" for the second time
and
> I
>> see they recommend "Mirror your Database and recovery log for "Server
> and
>> storage pool protection". I wanted to make sure there was not a
>> performance issue or anything else.
>>
>> Have a Great Day,
>> Eric Jones
>>> * eric.j.jones AT lmco DOT com
>>> *: 607-751-4133
>> Cell : 607-972-7621
>>
>
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