On 23 Jul 1999, Chris Jones wrote:

>Roger> AFAIK, with an Exabyte the optimal block size is 56 KB.
>
>I think we used 63k, when we had one of those.  But I don't remember
>where we got that number; it might have been out of a manual, or it
>might have been out of thin air.

We have a manual hanging around somewhere from Exabyte (or maybe from
Sequent) which came with one of the first Exabyte drives we got.

AFAIR, each stripe (i.e. head rotation) on the tape holds 64 KB, of
which 56 KB is available for user data and 8 KB is used for CRC.  If
you write a block which is less than 56 KB, the remaining space in that
stripe is unused.  If you write a block which is larger than 56 KB, the
excess data goes into the next stripe and then the remaining space in
the second stripe is unused (or may be unused if you don't write the
next block quickly enough).


Roger

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