==> On Tue, 6 Dec 2005 11:58:01 -0500, William Boyer <bjdboyer AT COMCAST DOT 
NET> said:


> If you collocate you run the risk of not being able to use the multi-session
> restore capability of the client. As for the n-servers backing up you will
> have N-files open...what if you're running a RESOURCEUTILIZATION higher than
> 2 on the client? You can have more that N files open if the clients have
> more than 1 data backup session running.

I agree about possibly having more than N files open for N clients; a high
mountlimit is important.

My guess would be that multisession capability won't be an important factor in
restore speeds once you have all the data on (de facto) random access media.
I'd guess we'd be back to network pipe or write speed of the recieving disk or
filesystem.

My experience on raids of SSA has been that trying to read multiple large
files simultaneously hurts my performance quite a bit; from ~27 MB/s sustained
read for a single thread, down to ~21 (total) if I try to read two, and ~18
(total) if I try to read three.  This will of course be ludicrously
disk-subsystem-dependant; but it's at least one unambiguous case in which the
idioms of tape optimization led me down a bad path when I applied them to
disks.


- Allen S. Rout