ADSM-L

Re: DLT 7000 Performance

1997-05-19 11:35:40
Subject: Re: DLT 7000 Performance
From: Dave Cannon <dcannon AT VNET.IBM DOT COM>
Date: Mon, 19 May 1997 08:35:40 PDT
>What other server parameters have you set up?  I am transferring my data
>from non collocated to the collocated tapes and the transfer rate is
>extremely poor for 6 DLT 4000 drives in the STK 9710 library.  It has been
>over 24 hours and only 843,388,247 bytes of data has been transferred
>though MOVESIZETHRESH is set to 1000 and MOVEBATCHSIZE is set to 40.

Transferring data from a non-collocated tape to a collocated tape can
be very slow because the server makes multiple passes through the database
and the source volume.  This allows files to be transferred by node/filespace
without requiring excessive tape mounts of the target media.

You should be able to achieve much better performance by using Move Data
to transfer files from the non-collocated tape to a disk storage pool
and then allowing the files to migrate from disk to the collocated tape
storage pool.

Dave Cannon
ADSM Server Development
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