Exchange Server

rdw24 · Guest

Have been pulling my hair out trying to design a new Exchange enviroment
based on best practices from Microsoft. This is enough to drive someone nuts!
We currently utilize pop3 mail thu a Linux box with about 500 users. Will
setup and install an Exchange enviroment with the mailbox count for users
moving to approximately 1400.
Overall plan is to setup an FE/BE config utilizing ISA 2004 out front w/ FE
residing in internal network. Have already purchased ISA and FE hardware and
am now grappling with best setup for BE. My current idea is to set up an
Active/Passive Cluster with a small SAN using the HP packaged cluster which
is (2) DL380 with a MSA1000 Fiber storage controller.
Here is where I get confused. Microsoft best practice recommends: ( Raid 1
for OS)-(Raid 1 for page file????)-(Raid 1+0 for SMTP queues)-(Raid 1 for log
files)-(Raid 1+0 for DB). Questions are as follows:

Why would you mirror the page file?
Do I need separate physical disks for each of the above sets?
Is an array neccesary for the SMTP que?
If I have more than one storage group do my trans logs have to be on
different physcial drives that are mirrored?

According to MS Optimizing Storage doc my layout would be as follows:
C:\OS, Exchange - Raid 1 - direct attached storage
D:\Page File - Raid 1 - direct attached storage
E:\SMTP and MTA queues - Raid 0+1 - SAN
F:\log files for Group1 - Raid 1 - SAN
G:\DB for Group1 - Raid 0+1 - SAN
H:\log files for Group2 - Raid 1 - SAN
I:\DB for Group2 - Raid 0+1 - SAN
Thats 4 physical drives in each server and a minimum of 16 drives in the SAN
- I only have 14 bay available in the SAN.
I would greatly appreciate any help.
Thanks,
Ron

Al Mulnick · Guest

Easiest first:

"Do I need separate physical disks for each of the above sets?" For some
yes, for some no. There's a trade-off for each. Read on..

"Is an array necessary for the SMTP que?" - No, but it will provide some
performance boosts in some situations. RAID 1 would be fine in many
situations. Your situation may vary, but it's likely it would be fine.

The reason to separate them as a best practice is because of I/O types. I'm
sure you're familiar with that concept already, but you can generally get
better perforamance and space with RAID 1+0 than you could with just RAID 1.
RAID 5 typically incurs a write penalty to update parity across the drives,
so some disk calculations will have you looking at it like this:
RAID 0 = write penalty (WP) = 1
RAID 1 = WP = 1
RAID 1+0 = WP = 1
RAID 5 = WP = 4

SMTP traffic is typically write heavy in nature with 7:1 w/r not uncommon.
Could be higher. That's going to be determined by message size, frequency,
and volume in most cases. The larger the message the higher the write
incurred because Exchange has made the decision to follow the RFC by
accepting the message before processing it. You accept every message before
doing anything with it in a default configuration. Bottom line? If you
don't have that much SMTP traffic you may be able to put those queues
elsewhere (not on the log file drives though).

"Why would you mirror the page file?" Why would you separate it?
Performance mostly. I think you could leave it on the OS drive and likely
be fine according to the chart you have listed.

"If I have more than one storage group do my trans logs have to be on
different physcial drives that are mirrored?"
It's all about trade-offs. If you have more than one SG, you'll have more
than one set of logs. One set for each SG to be exact. Since log activity
is serial write in nature, you may want to separate these to avoid
performance issues related to disk latencies. Then again, some SAN devices
can mask this along with buffers in the application etc. Typically, it is
recommended to separate these to their own disks (phys) to alleviate
bottlenecks related to disk latencies and to allow for better recovery if
you lose the store or the binary drives.

Was it me and I wasn't going to consider the cluster considerations I might
lay it out like this:

rdw24 · Guest

Al,
Thank you very much for your response. This does answer the questions I was
having regarding the physical disk requirements.
Thanks again,
Ron

"Al Mulnick" wrote:

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