3390 mod3 vs. mod9 performance

[art.mcewen]

Hi folks,

Our FM provider wants to know if we want our new DASD configured as
3390 Mod 3s (as our old stuff is) or Mod9s Oh and they want to know
before this weekend.

I like the idea of the larger logical volumes, is there any downside
from a performance point of view?

Thanks,

Art.

[Walter Schneider]

Hello,

I/O performance will almost be the same because the real, physical
disk-arrays behind the emulated 3390s are quite the same (as long as we talk
about today's storage technologies...). But another imoportant issue to
consider is I/O-contention: since 3390-9 can store three times more data
than 3390-3, it becomes more likely that data on the same logical volume
will be accessed simultaneously, which might lead to i/o-queuing in the
operating system's Unit Control Blocks (UCB)...

Cheers - Walter.

<ar********@moh.gov.on.ca> schrieb im Newsbeitrag
news:11**********************@z14g2000cwz.googlegr oups.com...

Hi folks,

Our FM provider wants to know if we want our new DASD configured as
3390 Mod 3s (as our old stuff is) or Mod9s Oh and they want to know
before this weekend.

I like the idea of the larger logical volumes, is there any downside
from a performance point of view?

Thanks,

Art.