Hi TSMers,
I want to ask a more kind of general question for any recommendations
Currently we have one local tsm-server and a library with quite a lot capacity.
We want to backup another site being some hundreds km away with a good Gbit
network
connectivity to our site. The remote site has about 200 clients with
a mixture of desktops,file-servers and so on - all 'normal' tsm clients.
Because an additional tape-library is not desired/needed there
seems to be 2 principally possibilities:
A) Placing a new tsm-server near by the clients at the remote site
(acting as source server) having no library but a big disk-cache
that may hold the backup-data of the last 4 weeks
The next-stgs would be on our local site also on disk and
finally migrating to tape.
For this the setup of an additional logical tsm-Server
acting as target server at the library-site is supposed.
B) Placing the new tsm-server nearby the library on the same
machine - having direct access to the tapes.
So the questions is:
Are both possibilities not anomalous ?
Does one of those has a strong preference ? - any caveats ?
From network-view: is one solution much easier to handle ?
My thoughts on A) : Running long distances it seems to be easier to have
the
tsm-server nearby the client because only this has to be tuned
to send/receive data from the library-link-node ... if it happens.
On the other side : if the server is nearby the clients - this will
lead to both short-distance client-connections and long-distance
target-server connections. So here i am concerned about
setting of the window-size of that tsm-server because it should be
small for clients and at the same time high for the target server
... because of the so called long-fat-pipes
- is this a problem ?
on B) do all clients have to be tuned on the window-size ?
From tsm-view B) seems to be easier -for example the use group-collocation-
From network-throughput the use of A) seems to be better because
data-transfers can be bundled and the transfer can be done when
its a good time to do so.
Last question is :
when using A)
is it a good idea or even perhaps 'a must' to make use of 'Cached Copy' ?
... or on the contrary is 'Cached Copy' something to avoid -especially
using virtual volumes ?
best regards
an thanks in advance for any hints !
Rainer
