I’ve read this and other similar
documents, but it doesn’t really answer my specific question. Basically:
Company purchases filer with 4 full
shelves of 14 disks.
Netapp recommends 16-disk raid groups at
install time.
Aggregate is created using 3 full raid
groups of 16 disks, per best practices recommendations of adding full raid groups
Filer is left with 8 spares (not 7 as I
incorrectly mentioned before)
My options at this point seem to be: 1)
add another raid group of 6 disks or 2) leave 8 spares until some future time
when capital budgets may purchase more shelves. I don’t think increasing
the raid group size is an option as I don’t believe you can increase the
size of existing already-full raid groups?
Anyway, it feels like a big waste to me to
have 8 hot spares, but if the performance or reliability costs of a 6 disk
RAID-DP group are too large I can live with it.
--
Michael
W. Sphar - IS&T - Lead Systems Administrator
SMBU
Engineering Support Services, BMC Software
From: Parisi, Justin
[mailto:Justin.Parisi@netapp.com]
Sent: Monday, March 19, 2007 3:01
PM
To: Jason Herring;
Subject: RE: FAS3020 - aggr best
practises.
Here's a good document to browse over for
this particular issue...
http://www.netapp.com/library/tr/3437.pdf
From: owner-
Sent: Monday, March 19, 2007 3:08
PM
To:
Subject: RE: FAS3020 - aggr best
practises.
You can
always go with a larger RAID group size - it does support up to 28.
However, at some point you have to bite the bullet and lose 2 more disks to
parity. It depends on how you want the math to work out in the long run.
The reason you want to add the disks in large sets is so you have a more level
writing of the data to the disks - you don't want to get 3-4 'hot disks'
slowing the whole aggregate down until the data is spread evenly among the
aggregate.'s new disks...
-----Original Message-----
From: owner-
Sent: Mon 3/19/2007 11:06 AM
To:
Cc:
Subject: RE: FAS3020 - aggr best
practises.
Point one reminds me of a question I've been pondering. I've got a
filer using RAID-DP with 3X14-disk raid groups, and currently 7 spares.
Ideally I'd only keep two spares, but I'm still not clear on the
pros/cons of adding a 5 disk raid group, effectively only adding three
more data disks to the volume.
I'm not in a space crunch currently but I certainly will be at some
point. Is it best to leave so many extra spares until I can add a full
raid group all at once? Or in my case is it not that important?
--
Michael W. Sphar - IS&T - Lead Systems Administrator
SMBU Engineering Support Services, BMC Software
________________________________
From: owner-
On Behalf Of Learmonth, Peter
Sent: Saturday, March 17, 2007 6:43 PM
To: Darish Rajanayagam;
Subject: RE: FAS3020 - aggr best practises.
Hi Darish
Welcome to NetApp and to Toasters!
1. You can do an "aggr add aggr0 56" or use the FilerView GUI
and add
all 56 of the new disks into the existing aggregate. You can physically
add the shelves and add them to the aggr while the filer is up and
running. I see no disadvantages, and that is the best practice.
(Add
disks in large sets, ideally the raid group size).