Actually, I have noticed that most internal RAID controllers tend to be 
pretty brain dead when it comes to RAID-10 (actually RAID 0+1), doing a 
round-robin read down both paths which results in *slower* I/O than a 
single disk (in a 4-disk RAID-10 anyway).  I actually did a head-to-head 
comparison, and with 4 disks, RAID-5 is faster than RAID-10 on most 
controllers.  The only exception is large, sequential writes (cache 
handles everything else), and with something like the NBU catalog, your 
large I/Os are reads which are always faster on RAID-5 anyway, given the 
same number of disks.

So, for my backup master, I have six internal drives.  The first two are a 
mirror (RAID-1) for OS.  Note:  DON'T put swap on RAID-5.  ...and the last 
four are a RAID-5 for catalog.


----Original message----
Date: Mon, 7 May 2007 11:42:25 -0400
From: "Paul Keating" <pkeating at bank-banque-canada.ca>
Subject: Re: [Veritas-bu] Hardware Recommendations for new setup
To: <veritas-bu at mailman.eng.auburn.edu>
Message-ID:

<052605A135CBC2438FE2D2B1A6A40B0F16ECCC at EXMAIL2.bocad.bank-banque-ca
nada.ca>

Content-Type: text/plain; charset="utf-8"

Will it be a master/media, or just a media with the Master at your Main
site?
Makes a bit of a diff, since a Master will have much more IO to the
local catalog.
With that much data, I would have no problem going with the T2000 with
the 4 disks.
Create a RAID10 RG, and cut it up into slices for OS and NBU.
With striped mirrors, you should have any IO issues.

You could probably make due with two separate RAID1 RGs, once for OS and
one for /opt/openv/.

The V240 has MORE than ample PCI IO for that amount of data, but if the
T2000 is cheaper, I'd go that way.
If/when you eventually need more performance for the catalog, you can
put it on FC-SAN disk, or an external FC array.

Paul


-- 
Joe Royer / SysAdmin / Digital Motorworks / 512-692-1028


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