ADSM sets the block size of all its tape/optical devices internally.
Setting it in smit has no effect, except for tar, dd, and any other
applications that do no set it themselves.

ADSM uses variable blocking on all tapes, ie. blocksize is 0.  Generally
however, for 3590 it will attempt to write out a full 256K block, which
is the largest allowed blocksize with variable blocking.  Some blocks,
eg. the last block in a series, will be shorter.

Craig Bell

>Hi,
>We tried to find the optimum block size for 3590 tape drive used by
>ADSM.  Right now we have itset at 1024, and so are all our backup
>tapes.  We are thinking about changing it to larger block size like
>around 6000, supposingly this will increase our I/O by a factor of
>4. Our initial test has shown that using the Unix dd command, the
>I/O does increase.
>        Any advice on this matter is greatly appreciate, thanks. PC.