Re: disk latencie problems on a brand new exchange server with 2 mailboxes!!!!!!!!

We also have a 7 terabyte EMC Nas box that i can put data on. However i was
not here when it was implemented and had no say so in the design of the
clariion storage. So i dont know how efficient this would be compared to the
local disk.


"Jef" <nospam@xxxxxxxx> wrote in message
news:ui9$ZqZFIHA.5328@xxxxxxxxxxxxxxxxxxxxxxx
Yes you are right it is RAID 5 with a total of 1 Terabyte. C:\ drive is
windows and D:\ is the exchange stores.....

should i take 2 of the drives and mirror them and then use the remaing 3
in a configuration?


"John Fullbright" <fjohn@donotspamnetappdotcom> wrote in message
news:eImbShZFIHA.1168@xxxxxxxxxxxxxxxxxxxxxxx
Figure a mirror for the OS, a mirror for the DBs, and a single drive for
the logs (or a single drive for the OS, a mirror for the logs, and a
mirror for the DBs depending on what fault tolerance trandeoffs you want
to make) you might be able to support 100 users at 1 IOP/user. There's
no way this system will support 1000 users.

From the description of the problem, odds are all 5 drives are in 1 RAID
5 array with the OS, logs, and DBs in seperate logical drives (or on the
same drive; from a performance perspective it's all the same spindles).
If this is the case, I would expect you to be able to support more than a
handful of users. In fact, is sounds like 3 is too many. When you size
disk, space isn't the only factor; you have to consider performance
requirements as well. RAID 5 is a bad choice for Exchange 2003.
Although it maximizes space, performace is less than half that of
mirroring (RAID 1 or 10). In particular, write performance is grossly
inadequate for and application with a 3:1 or 2:1 read/write ratio. RAID
5 is appropriate for applications that:

1. Require a lot of space.
2. Write data infrequently
3. Read data mostly

These critera descibe some file servers. These criteria do not describe
Exchange. Back in the Exhcange 5.5 days, when you had an 8:1 read/write
ratio, you could squeak by with RAID 5 for the databases. You still put
the logs on a mirror. In a modern Exchange 2003 environment with Outlook
clients caching, you read/write ratio is more like 2:1. The RAID 5 write
penalty is way too high.

John



John


"Mark Arnold [MVP]" <mark@xxxxxxxx> wrote in message
news:sh7sh3110fmui171q55cbmcn7bdmvb72n2@xxxxxxxxxx
On Tue, 23 Oct 2007 10:55:13 -0400, "Jef" <nospam@xxxxxxxx> wrote:

we have an old exchange 2003 server that recieves alot of disk latencey
problems using MOM 2005. We just purchased a new Poweredge 6850 16 gigs
of
ram quad core 3.66 with 5 15k hardrives. I moved about 3 mailboxes to
this
unit and i am recieving disk latency problems (see below) from the new
server now also. Why is this happening, will this get worst when i move
all
1000 mailboxes to it?


High Disk Read Latencies for the past 10 minutes
PhysicalDisk: Avg. Disk sec/Read: _Total value = 5.49850987944241E-02.
The
average over last 10 samples is 0.0549851.


You haven't got anywhere near enough disks in my opinion. Sure,
they're fast enough but five disks? How have you got them carved up?
If they're in a single RAID5 partitioned into drives that wouldn't be
the best way.






.

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