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Disk Size for Nest OS Release of IBM i



fixed

It has been mentioned here that V7R2 ( or whatever the new release will be
called ) will require a 70GB Loadsource.

The real question here is what size to we really need? I believe this 70GB
drive spec is based in the older SCSI drives not the physical space
required. Where I am going with is vSCSI disks presented to IBM i from VIOS
or a Hosting IBM i partition or even the size of disks that a SAN will
present to IBM i.

Let's talk 70GB SCSI Drives. If I Mirror my LS with a pair of 70GB drives
then the OS will see 70GB. If my 70GB LS is part of a 4 drive Raid set I
will see only about 53GB. INa 3 drive set I don't know as I Haven't done a
3 drive set but if everything is even that will make those drives around
47GB.


Here's why I ask.
New Power7 with 8 139.5 drives. After Raid5 those drives are 122GB In this
exampleI want to have an IBM i Hosting partition and 2 IBM i Guests. IBM
suggest to have a minimum of 6 vSCSI drives in a partition for
performance. Now in creating cSCSI drives in IBM i for an IBM i Guest you
loose about 7% if I remember correctly. So each drive on the host needs to
be about 75GB to present 70GB to the guest. So I need 12 of these. ( 12 x
75 ) = 900GB that will leave about 76GB in the HOST. or about 71% usable if
you keep the HOST at 90% used. If I can use slightly smaller drives I would
a little more breathing room or room for a set of OS Image catalogs etc.

No in this example I don't want run any work other than hosting in the HOST
partition.

Thoughts, Comments etc?

--
Kirk





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