Re: SSD/HDD Performance & Balancing

Joe Wood <wood3875@xxxxxxxxx> wrote on Thu, 26 Feb 2015 00:37:26
GMT:

The data comes from display device parity status.

574E DC06 is not referenced, & 574E DC07 shows twice, driving
two raid sets of 6 drives, and 12 drives. Why 6 & 12 ?

If you/we could start over, how would you recommend these 18
drives (same model/size) be paired, grouped or parity'd ?

Ah, display device parity status may not show both controllers.
I would check using the path screens in service tools. Or since
you don't have access to that look at data in QAPMDISK to see if
the IOA DC06 shows up in field DSIOARN. An SQL along the lines
of

SELECT intnum, dsioarn, dsarm from QPFRDATA/QAPMDISK where
intnum = 1 and dsioarn = 'DC06'

(may need to change QPFRDATA to where your performance DB files
are located)

will show whether or not one of the parity sets is using the
controller or not.

If this were my system, I would schedule a weekend outage and

- full system backup
- stop parity protection for the 2 arrays behind 574E
- make sure parity optimization is set to performance
- restart parity protection for the drives behind 574E

You should then end up with 2 parity sets of 9 drives each.

As to why you ended up with 6 and 12, that is a good question
and there are many potential answers. One possibility is you
started with 12 drives and later added 6 more hoping for better
performance or needed that much more storage.