Hi,

> I have a customer who wishes to assess the maximum risk he would incurr in
> the following situation;
>
>
> We have a copygroup for backup set for 31 day point-in-time recovery. We
do
> not have nolimit for any copygoup parameters - we assume there will only
be
> a single backup each day.
>
>
> The customer has a 5 node cluster. 1 -> 4 are production machines, 5 is a
> failover machine.
>
> They would like to know the risk involved when, should a machine be failed
> over to 5, they back up the data now visible to 5 under the nodename of 5
> instead of the original machines nodename, & the original machine
continues
> to run a backup as well (this would only see local disk, as a portion of
the
> failed over machines disk is now visible to 5, and hence mark all the
> non-visible files as inactive)
>
> We have told them backups would become inconsistent within filespaces that
> have the same names across machines, and showed them how fiddly it would
be
> to restore a machine if they had only had one failover occurr in a 31 day
> period. They would like to know exactly what the risks are if they have
> multiple failovers within a month, and have multiple machines backing up
> same-named files under a single nodename!!
>
It depends how the cluster is configured. The TSM Client must be part of the
resource group and inside of dsm.sys you must create several stanzas with
the TCPPort and nodename forced to diferent numbers and names. And when you
start the TSM Client Scheduler you must force the right dsm.opt
with -optfile option.

> They won't take 'It won't work' as a answer, they would like to know how
it
> will impact the point in time restore capability for a particular machine,
> if they keep track of what machines failed over when.
>
> As far as I can work out with pen&paper, in a worst case, for a 3 machine
> cluster where 1 & 2 can failover to 3 at any time, the maximum impact
would
> be to reduce the point-in-time restore capability for a particular machine
> by the number of days that machines have been failed over to 3 in the last
> 31 day period, because files with the same path filename on machines 1 and
2
> would expire early if they change more often on one machine than they do
on
> another.
>
It's impossible two machines failover at same time to a third machine if the
first two have the same filesystems. They even would import the VGs. You
must check if this information it's true.

> I get a headache if I try and extend this to a 5 machine cluster.
>
> do you other TSM'ers agree?
>
Yes, to mange would be a little bit hard. But the client probably has good
administrators. Or in worst case you can sell a support contract to
administer his environment. :-)

> and, I know from our perspective this is a 'silly' thing to work out
because
> they should listen to the advice of the people that know & switch to
backing
> things up correctly, but they are insisting they have this info...
>
> Any help is much appreciated!
> Thankyou,
>
> Matt.
>