Matt,
Can you share more about the distance and SAN infrastructure that TSM I/O
travels through? Many answers would be depending on them.
As we know, TSM DB mirroring is at the SW level after OS or HW. First, try to
avoid the redundant mirroring at TSM application with OS or HW since you
concern about the latency. Also, when you said 'remote SAN devices', I assume
you plan to use more than one disk subsystems. If so, instead of configuring
mirror volumes at LUN level, you may consider it at the controller level such
as remote mirroring with EMC, FAStT, ESS or SVC. Usually, in a FC SAN you don't
have much latency among devices with 2Gb/4Gb interfaces. Especially, TSM write
I/Os will be acknowleged at the cache level than the actual disk level, which
minimize the possible latency. Be careful with your SW mirroring policy that
potencially adds I/O overhead.
You can achieve the data or LUN protection at various levels today, but
considering the advancement in HW technology including FC/IP SAN, there are
more options for TSM admins to get even better protection without affecting
app's performance. Trying to come up wit at lease a dozen of recovery scenario
with your existing system, will always help with better designing TSM with SAN
for any DR situation.
Gus
>>> Matthew.Warren AT POWERGEN.CO DOT UK 07/13/05 11:52 AM >>>
Hi *SM'ers,
We are looking into the possibility of placing TSM DB mirror volumes on
remote SAN devices. Has anyone already done this, and have any gotchas
or issues?
My first concern would be latency, but With mirrorwrite sequential it
seems from the explanation that the primary mirror volume is the one
that would be hurt by latency, not the secondary mirror volume.
Would that be the case? Or, will TSM wait for the secondary mirror write
to finish before embarking on the next primary mirror write on that DB
volume?
Matt.
Matthew.warren AT powergen DOT com
Matthew_j_warren AT hotmail DOT com
http://tsmwiki.ciom/tsmwiki/MatthewWarren
Computer says 'No'..
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