Matthias,

We have 3590 SCSI connected drives to an R24. The best 3590 transfer rates
we have observed have been with BACKUP STG (disk to tape, or tape to tape)
achieving 4.5 MB/sec. More typically we see rates 2.0MB/sec - 3.0MB/sec.
Migration from disk to tape is usually slower.

The profile of filesize is very important in determining performance. Here are
just a few samples of real situations that we have observed, moving about 1 GB
of data each time:

        Average filesize        BACKUP STG      MIGRATION
        =================================================

                 60 KB          2.4 MB/sec      1.4 Mb/sec
                100 KB          3.4 MB/sec      2.1 MB/sec
                150 KB          3.6 MB/sec      2.6 MB/sec
                850 KB          4.5 MB/sec      3.9 MB/sec

There are several ADSM parameters which greatly affect the performance of
data throughput. These figures were taken when the ADSM DB is on 7137 disk
array; ADSM LOG on SSA; storage pools on SSA. LOG mode is ROLLFORWARD.

Also, DB buffer pool size = 6144; LOG pool size = 1024; DB size was 2 GB;
TXNGROUPMAX = 256;  MOVEBATCHSIZE = 1000; MOVESIZETHRESH = 500.

File sizes less than 60KB are bad news; I have some figures taken before the
parameters were set as decribed - but more like 1 MB/sec.

It is my understanding that 3590 performance could be improved if a much
larger buffer size were to be used by ADSM. I believe 32KB is the current
value used and that at 64 KB rates of 7 MB/sec could be achieved; at 128 KB,
9 MB/sec - assuming other things could keep up ...

Another question, for IBM, could anyone confirm that ADSM (2.1.0.3) is
making good use of 3590 addressing capability to optimise file restores
and retrieves. What I mean is, is the 3590 track taken into account when
determining the restore/retrieve order for a set of backup/archive files.

Thanks.

Regards, Sheelagh
------------------------------------------------------------------------------
Sheelagh Treweek                         Email: sheelagh.treweek AT oucs.ox.ac 
DOT uk
Sheelagh Treweek                         Email: sheelagh.treweek AT oucs.ox.ac 
DOT uk
Oxford University Computing Services     Tel:   +44 (0)1865 273205
13 Banbury Road, Oxford, OX2 6NN, Uk     Fax:   +44 (0)1865 273275
------------------------------------------------------------------------------
=========================================================================