"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 08/20/2003
07:54:54 AM:

> "No query" restore has nothing to do with minimizing tape mounts for
> restore. For a given restore, TSM mounts each needed tape once and only
> once, and reads it from front to back.
>
> The most visible benefit of no query restore is that data starts coming
> back from the server sooner than it does with "classic" restore. With
> classic restore, the client queries the server for all objects that match
> the restore file specification. The server sends this information to the
> client, then the client sorts it so that tape mounts will be optimized.
> However, the time involved in getting the information from the server,
> then sorting it (before any data is actually restored), can be quite
> lengthy. No query restore lets the TSM server do the work: the client
> sends the restore file specification to the server, the server figures
out
> the optimal tape mount order, and then starts sending the restored data
to
> the client. The server can do this faster, and thus the time it takes to
> start actually restoring data is reduced.
>
> In either case, for a given restore, TSM will restore the files and
> directories in a manner that optimizes tape mounts. If it so happens that
> a file is restored before it's parent directory is restored, then the
> client will create the parent directory, restore the file, then restore
> the parent directory when it encounters it in the restore sequence.
>
> Regards,
>
> Andy
>
> Andy Raibeck
> IBM Software Group
> Tivoli Storage Manager Client Development


Excellent post.  Clear and well written.  This should be in the FAQ (if
it's not already).