Scott is on the money, although I’d make two comments:
    - disk replacement depends on how hard you push your disks & personally I would use 1 disk / shelf + 1 spare initially and throttle back over time based on trending data.
    - DP is strong protection, but a magnetic media failure and + single disk failure can be a double disk failure for a single file... Unlikely with disk scrubbing, but if you’ve got very important data it might be wise to keep the extra disks kicking around.

-Nick


On 2/20/08 8:54 AM, "scott.belisle@americas.bnpparibas.com" <scott.belisle@americas.bnpparibas.com> wrote:


I would recommend grouping all your 15k drives in one aggr, and all the 10k drives in another.  Use the default 16 disk setting.  This should give you optimal performance.  I'd also keep a single 144GB and single 72GB as spares.  RaidDP gives you pretty decent protection so you shouldn't need a spare per shelf.  I personally use one spare per 3 shelves of a drive type especially with FC drives.  My 2 cents =)

Thanks,
Scott





Internet
klises@caminomedical.org
Sent by: owner-toasters@mathworks.com 02/15/2008 11:17 AM

To

toasters

cc
Subject

raid group question for new aggregate



I checked the NOW site, and didn't really find anything that seemed
pertinent for 7.23 in regards to setting up number of spindles for raid
DP.  I did read the 7.2 storage mgmt guide btw .  Here is my situation:





I brought over 3 shelves from some older heads, and hot added to a
current loop. Shelves 2-4.  Shelf 1 was already provisioned with 72GB
disks.  Currently, I have 1 aggregate of 3 disk (root vol), and 9 disks
for another aggregate; 2 hot spares  (full 72gb shelf, shelf 1)



Here is my question.



What is the best layout for raid dp for my new 3 shelves I just added?
I do not want to add the 3 new shelves to the existing aggregate.



I know the default is 16 when creating a new aggr, maybe I should
default to that.  I don't know if I will be adding more disks in the
future to this aggregate.



Shelf 4  I have 1 shelf of 144gb 15k  (14 spindles)             new


Shelf 3  I have 1 shelf of 72gb 15k (14 spindles)                new

Shelf 2  I have 1 shelf of 72gb 10k (14 spindles)                new

Shelf 1  I have 1 shelf of 72gb 15k (14 spindles)                already
provisioned



I want to dedicate at least 1 or 2 hot spares for the 144gb (obviously).
I already have 2 hot spares from shelf 1.





I care more about performance then raid reconstruct in the event of a
disk failure.  This aggregate will be used primarily for CIFS.





If I missed a document that discusses this better, please let me know.



Thanks!!




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