Denys Beauchemin wrote:

> David brings up a good point about multiple drives in the array.
>
> To my mind, I am uncertain about the benefits of having multiple drives
> declared in the array versus declaring a single big device or at least
> as many as there are controllers.  I definitely see the benefits in
> having multiple volume sets, but perhaps not many more devices beyond
> that, except to get by the MPE limitations on drive sizes.

There are a 2 that I can think of right away:

- more MPE LDEVs means more parallel IOs possible, each
   SCSI_DISK_AND_ARRAY_DM can handle up to 8 'parallel' IOs
   from an MPE driver's standpoint.

- there are limits in the size of certain MPE data structures
   on each LDEV, e.g. the size of the file label table (limited
   to 256k entries).  If you have lots of small files, more LDEVs
   mean less chances to hit that limit.

Goetz

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