Re: Large Number of Storage Groups
- From: Andy David {MVP} <adavid@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 30 Aug 2007 20:36:13 -0400
On Thu, 30 Aug 2007 08:00:00 -0700, Mike A <nospam@xxxxxxxxxxxxxxx>
wrote:
We are aware of the SG design. At one time Microsoft's position on
this was to minimize the number of SG's and that was what our design
was based on. EMC had originally recommended RAID 5 configs for the
db's. The disk read performance was really bad, and we ended up
redoing the existing servers with RAID 10 configs for our existing
servers and configuring all new servers this way, right off the bat.
For 2007, I am planning one DB per SG. I wasn't sure if Exchange
could use mount points or not. That would definitely solve the
problem. For or exiting config, performance is stable at this time,
and I am hoping it will remain that way until we start moving towards
2007.
Anyone know of organizations right now running large back end
servers? I am wondering if I can get away with planning around 2800/
server. The hardware would be quad core with 16GB RAM.
Much of that depends on your user profile.
In of itself 2800 is not that high of a number of users, but throw in
large mapi client mailboxes, Blackberrys, Communicator, modular
messaging, cache vs. online mode, etc.. and having that number of
users on a server may not work for you.
EMC and Microsoft ( on the EHLO blog) can definetly provide guidance.
.
On Aug 30, 6:30 am, "Mark Arnold [MVP]" <m...@xxxxxxxx> wrote:
On Thu, 30 Aug 2007 06:00:31 -0400, "Mike Abbaticchio"
<nos...@xxxxxxxxxxxxxxx> wrote:
My current layout is Exchange 2003 with 2 SG's / 8Db's all on the same same
RAID 10 LUNs, with spearate RAID 1 LUNs for xlogs. I went through all the
IOP calculations with EMC and have acceptable performance, but the read
times on the DB drive were never as good as I expected. Needless to say, I
am being real careful with the 2007 plan.
Thanks for your response.... I was just wondering if there was a way out of
the drive letter limitations. I will more than likely end up using less
storage groups and end up with larger db sizes as a compromise.
Mike Abbaticchio
I'm never convinced what RAID10 gets you on platforms like EMC. Are
you expecting drives to fail that often? The performance gains are
neligible. Far better would be to go RAID6 and spread out on all those
suddenly available spindles.
Like the other posted says, Mount points are the way to go in terms of
eliminating the drive letter challenge. You've no choice later in 2007
if you fill the full 50 stores anyway :-)
Your configuration is not in line with 2003 best practice though (I
assume you are on W2K3?). The "fill a storage group with stores and
then make another storage group" thing was correct in 2000 (on 2000 or
2003) but not in 2003 on 2003. You are affecting your log disk write
performance and potentially hitting buffer problems.
First job for me would be to make two more SGs and spread all the
users across them. Then I'd look at how my logs were performing. Then
I'd have a think about the read cache on the EMC (whatcha got? DMX,
Clariion, Celera?)
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