Re: LPAR Placement of 720 Base Raid Controller

Kirk Goins <kirkgoins@xxxxxxxxx> wrote on Fri, 10 Jan 2014
15:42:47 GMT:

*I can't put the PCIe card based SSD inside the CEC*

Why not? All slots consumed? But as Larry points out these
slots do not have concurrent maintenance capability.

Current Setup
8202-E4C 6core.
IBM i Hosting partition with several guest IBM i partition.
Current Base Disk Backplane in the CEC does NOT support Raid
NO Disks in the CEC

This means you have a 6-drive bay system.

Thinking of doing the following.
Upgrading the CEC Disk Backplane to the one that supports Raid
Install 4 SSDs on the new backplane ( ie in the front of the
CEC ) Assigning Disk Controllers Directly to one of the Guest
parititions So it will see them as SSDs not just some other
Virtual Disk.

The DVD & (if present) tape device will go to the guest
partition too. While you get 2 additional bays and can install
up to 8 SSDs, the write cache included on the higher function
backplane is 175MB versus the 380MB for the 5805. If you're
planning to RAID5 protect the SSDs, you might as well go with
the option I outline below because performance will be pretty
bad with a single parity set.

Larry, Pete or anyone else see any issues with this setup?
Really don't want to spend upwards of $10K for a pair of
5805's and an EXP24s
for just 4 SSDs

I don't do prices, but you might want to consider looking at the
no cache disk adapter which can be purchased as a single adapter
and it supports up to 24 SSDs in the EXP24S, so you can grow.
RAID5 protection is still possible for the SSDs and it will be
significantly better for just 4 SSDs than any dual adapter setup
with write cache. It will perform better than the PCIe SSD
adapter with 4 SSD modules because the SSD technology is
significantly better than the SSD modules.