Re: 99.9 service availability

In the CCR model, you'd use log shipping to send the logs to the passive
node where they are replayed. When a log file fills to 1M, it is shipped,
validated, and replayed. That may be every few minutes or less on a very
active SG, or a lot longer if the SG is not so active (yes, there is the
dumpster on the hub, but there are issues as to placement as well). MS
recommends VSS backups on the Seconday node due to the IO intensity of copy
on write snapshots and the IO activity associated with validating the backup
(per kb822896), so backups potentially lag as well. There's clearly a gap
here depending on how busy the storage group is. If it's right for you
really depends on what your SLA is. At a minimum, with Netapp you get space
utilzation similar to RAID 5 with no write penalty. You also get to
leverage the low IO impact of snapshots on the platform and prerform them on
both the active and inactive nodes at least eliminating this part of the
gap.

In the designs Mark refers to, you would you the good old shared storage
cluster and snapmirror replication to a DR site using standby clusters.
Locally, The RTO is as long as it take the cluster to failover (a couple of
minutes) and the RTO is up to the minute. In the event of site failure, the
RPO can be as low as 5 minutes (it's dependent of the frequency of log
snapmirror updates) or so and the RTO is a few hours (because you implement
a standby cluster). The point with the RPO in this case is that it is
expressed in terms of time - the way business objectives are expressed.
This is very similar to designs for Exchange 2003 out there and proven in
the real world today. It falls within the support policy for replication of
Exchange data because snapshots, not live data, are what is replicated.

http://www.netapp.com/go/techontap/matl/three-tradeoffs.html
http://www.microsoft.com/technet/technetmag/issues/2006/10/FailoverClusters/default.aspx


John

"Jesus Martin" <jesus.martin@xxxxxxxxxxxxxx> wrote in message
news:ev4I%23KVUHHA.5060@xxxxxxxxxxxxxxxxxxxxxxx

Mark, I don't know so much about SnapMirror but my as far as I know NetApp
SnapMirror provides Data Availability copying the DB and logs to a
secondary location using a cheap storage (if you want of course) what I
don't see here is the service availability support. CCR enables you to use
a passive node to support your users when the active node is down. Using
the NetApp solution you should create a new storage group pointing to the
replicated DB, this process is not immediate so the service can be down
for a while

What would you recommend here?

thanks

"Mark Arnold [MVP]" <mark@xxxxxxxx> escribió en el mensaje
news:7o49t29q9ds9k4gng4k93n504ajbs7p53s@xxxxxxxxxx
On Thu, 15 Feb 2007 18:02:34 +0100, "Jesus Martin"
<jesus.martin@xxxxxxxxxxxxxx> wrote:

They are talking about using NetApp Snapmirror for Exchange

thanks

If you have SnapMirror then you can put away all thoughts of LCR and
CCR as you just do not need it.
Sit down with your storage admin or call the people who sold you the
Filer and talk to them about Exchange 2007 configuration. They may not
be up to speed on it it's the same as 2003 so they will be able to
help you fully.

Take a look at: http://www.netapp.com/library/tr/3407.pdf which will
help you understand SnapMirror if you're not already familiar with the
product.




.

Relevant Pages

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