Re: New Power8 Disk Perf Issues

At this time there is a very limited number of EXP24S disk expansion units
you can attach.
If you're used to attaching multiple controllers, and having thirty or so
35GB drives per lpar, and having 5-6 lpars, you are seriously going to
have to rethink operations.
You'd be better off to use much larger drives (35GB drives are dead
anyway). By 'much larger' I'm talking like 775GB drives.
And host it all on an lpar of IBM i. One controller instead of 5-6
controllers to support each lpar. With no card expansion units available
at this time it's worth the thought.
And before you start freaking out about the lack of arms keep in mind that
I guested multiple lpars on Power 8 spinning disks, using huge drives that
only went at 10k when I was used to many much smaller drives going at 15k,
and still got better performance. That was just our evaluation machine.
On our two biggest production machines we went even better. Instead of
spinning disks we have all SSD's. Yep, filled up our 5887's with 775GB
SSD's, RAID 5 with hot spare.


Rob Berendt