Cecelia, Since I know your environment (z/VM with NOMAD databases on a DS6800), I
wouldn't expect any measurable performance hit from using mod 9s. With raid technology, the concern should be directed more at balancing th e I/O rate across LCU's rather than at the device level within an LCU. The physical arms in a drawer can service only so many I/O's for that LCU regardless of the number and size of the volumes in that LCU. Queueing a t the device level is a very minimal concern when there is other significan t activity in the LCU. Under the old non-raid technology there are indeed potentially significan t performance concerns with mod-9s. A lot depends on the data access rate and patterns. PAVs are good. Brian Nielsen On Tue, 25 Apr 2006 13:03:26 -0000, Dusha, Cecelia Ms. WHS/ITMD <[EMAIL PROTECTED]> wrote: >I have a question that pertains to performance. > > > >We currently have 3390 mod 3 defined volumes. The customer requires a >larger mini disk size than what will fit on a 3390 mod 3. We are planni ng >to create 3390 mod 9s for their larger mini disks. Would someone explai n >the performance hit that will occur by placing their data on a larger >volume. Maybe it is insignificant, but I seem to recall the architectur e >permits a limited number of accesses to the device. If there are a larg e >number of users who require access at a given time, then the users could end >up waiting for the device? > > > >Please advice. > > > >Thank you. > >Cecelia Dusha > > >======================== ========================= ========================
