Roberto is correct.
The host partition has (say) 48 Arms. When you create a NWSSTG object
(which IS the disk unit for the client) that storage is spread across
all of the 48 arms of the host. This is repeated for at LEAST 6 arms
per client. So you can see that the client is 'virtually' accessing all
48 host arms.
On the host side they only 'See' the number of 'arms' attached,
(remember minimum 6 for performance) but I/O to each of those 'arms'
will spread across all 48 arms on the host.
iDevCloud started on POWER5. Each partition started on 4 17GB 10K RPM
physical disks. The partitions ran "OK" as they are very VERY low usage
(often one person) but PTFs and IPLs were aweful. Today those
partitions are hosted on POWER7 and many have only 3 drives! (Same
capacity with 3 unprotected vs 4 RAID drives.) PTFs on these are vastly
faster than the old physical setup as are IPLs. If you watch the host
partition the disk arm 'busyness' is nice and even during client activity.
By the way if you use SAN storage it works the same way. (*DISCLAIMER:
Assuming the SAN is set up correctly!!!!!)
- Larry "DrFranken" Bolhuis
On 10/17/2013 8:38 AM, Roberto José Etcheverry Romero wrote:
I believe that since the ASP spans the whole 12TB of disk, 6x70Gb or
whatever you want to use will be spread along all 12TB so you get mora
than 6 arms even when using small disks versus using a dedicated
controller and only 6 disk for each LPAR.
On Thu, Oct 17, 2013 at 9:25 AM, <rob@xxxxxxxxx> wrote:
The only part I'm confused on, I thought on a hosted partition, the data
is still spread across all arms. Can you clarify/elaborate?
yeah, I'm anxious to know that also.