Re: RAID5 parity sets

[Dave_Dahlstrom@xxxxxxxxxxxxxxxxxx]

I posted same question(s) on AS/400 Forum BBSN today. I have two existing
parity sets of 5 and 7 drives each(IOPs are 2748 and 6533 on a 720-2061). I
want to add 8 more drives (6713s). I believe that I can get full capacity
from additional drives by adding them to existing parity sets so that each
would have 10. Does this make sense?

It does make sense as long as the capacity of the drives attached to the IOP's
are the same


 Current sets have parity spread across4 drives. I've seen some parity sets
 on my other systems that have parityspread across 8 drives.
 Is this determined by the system?

You will have to stop parity and start parity after you have  added them
Then this will spread the parity accross 8 disks instead of 4.
If you just add the disks to the ASP without stopping parity
then they can be included in the parity set but only spread over 4 disks.

For a 10 drive parity set, what is the optimum setup?

The optimum setup for Parity is to spread parity accross 8 disks,
this enable's you to rebuild a failed disk from 1/8 of the disk instead
of a quarter thus reducing the length taken to rebuild.

 Is there a reason that I should keep parity sets no larger than 8? I appreciate
any suggestions.

I do not know the answer to this but would be interested also


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