Re: RAID question

[Kirk Goins <kgoins@xxxxxxxxxxxxx>]

Jeff Carey wrote:
> 
> We just added 2 drives to an S20 that previously had 4 drives on it (one
> RAID set).  I used SST to add the new drives to device parity protection
> and then added them to my ASP.  As we were not adding a full RAID set, I
> expected the system to mirror the devices.  Instead, I see this on the
> WRKDSKSTS display:
> 
>                     --Protection--            --Protected--
> Unit      ASP       Type      Status          Size
> 1         1    DPY       ACTIVE          3145
> 2         1    DPY       ACTIVE          3145
> 3         1    DPY       ACTIVE          3145
> 4         1    DPY       ACTIVE          3145
> 5         1    DPY       ACTIVE          4194
> 6         1    DPY       ACTIVE          4194
> 
> This gives more DASD than if the new drives were irrored, but are they
> really protected?  If so, why am I seeing all 4194 MB?
> We are at V4R1.

A raid set can have up to 10 drives if I remember correctly. Depending
how the get added to the set, the 400 will either stripe the first 4
units with both data and parity info, or if a whole set 8 or more drives
he stripes them all. Your case is the first. Since all parity info is on
the first 4 drives, any new drives become ALL DATA while the protection
for those drives is still on the first 4 and therefor protected.


If had other drives that were mirrored and you had added these without
adding to the p-set then they would have mirrored. If no other drives
were mirrored then you would have ended up with 2 unprotected drives.

-- 
Kirk Goins
Blue Heron Consulting,Inc
2418 SE Burnside Rd #321
Gresham, OR 97080
503-618-1493
EMAIL kgoins@ix.netcom.com              
      kirk_goins@compuserve.com
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