> 1. All network speed aside, does the number of files and sizes of the
> files in the saveset affect the speed of recovery for the saveset or
> just the amount of the data and the speed of the drives?

Yes, it does.  Recovery of small files is usually dominated by the speed
with which the client can create files in the filesystem.  This may
reduce the throughput.  

This isn't a problem with larger files.

> 2. In general, is it safe to say that recovery will be slower than
> writing since it has to de-multiplex the data from the other streams
> that were written at the same time?

You're talking two different things here... 

The data throughput of one recovery stream may well be lower than the
data throughput of multiple backup streams..

However the amount of time taken for the original backup will likely be
comparable to the time for the restore (plus time for the client to
manage file creation).

> 3. What might you expect for recovery times knowing the speed of your
> writes and target sessions? Can any rough estimates be expected?

Don't put too many sessions on a volume if the clients are "fast"
(relative to the speed of the tape).  The purpose is to keep the drive
utilized.  The fewest number of clients that accomplish the goal, the
better.

If you have 'n' equivalent sessions, then you'd expect throughput (both
backup and recovery) to be about max/n where max is the maximum speed of
the network/server/drive path.  

> 4. Is there a way, aside from just eyeballing and watching the clock, to
> calculate the speed that the data is being recovered at? 

You might use a network monitor to watch the traffic.

You could use iostat to see the speed of the data coming from the drive
(which would include all the streams)


-- 
Darren Dunham                                           ddunham AT taos DOT com
Senior Technical Consultant         TAOS            http://www.taos.com/
Got some Dr Pepper?                           San Francisco, CA bay area
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