On 12 Apr 2003 at 0:31, Roger Deschner wrote:

> I actually tested this. Striping is very, very bad for the TSM
> Database. 1:1 is best.
>
> TSM Database I/O is totally random. Response time is much more
> important than throughput - it never transfers a large amount of data
> in a single operation. It's all small amounts of data, scattered
> randomly across the entire database. Therefore trying to get several
> physical disks working at once to do one I/O operation just slows
> things down.

This is a very interesting discussion, because it's exactly opposite
of what we do on our random access Oracle databases.  For highly
random, transaction oriented, oracle database we strip the db as wide
as possible across as many disks as possible.  We aren't trying to
get the drives working together, instead, we want every disk being
hit by random accesses all the time.  Stripping can increase
sequential throuhput, but it should also scatter your data across the
drives.  I would never set up a Oracle database that is processed
randomly by putting a database file on a single spindle.


Q)  How does TSM allocate db block?  Does it go down the free block
in a db file, or allocate free blocks across db files?

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