RAID 1/0 or RAID 5?

RAID 1/0 or RAID 5?

Post by Gre014 » Sat, 06 Jun 2009 23:01:02


Does anyone have a suggestion of what RAID to use for Exchange 2007?
We will have 125 users with only 50 using Outlook, the others using
Outlook Express. We will use 5, 300 GB 15k drives. I've read that
RAID
1/0 is recommended but RAID 5 would give us more space. Suggestions?
 
 
 

RAID 1/0 or RAID 5?

Post by Oliver Moa » Sat, 06 Jun 2009 23:24:16

Hi there,

RAID10 will yield the best IO gains, RAID5 has a write penalty of 4,
compared with 1 of RAID10.

RAID5 will give you more storage space as it uses parity and not mirroring.

However for 125 Users if you give each user a .3IOP profile RAID5 will
handly that just fine.

Use the Exchange Storage Calculator and TechNet resource to size your IO and
Storage correctly.


http://www.yqcomputer.com/

Oliver

 
 
 

RAID 1/0 or RAID 5?

Post by Charles Ca » Sun, 07 Jun 2009 00:29:03

Since it sounds like this will be small business setup, I would consider supportability, in additional to cost and efficiency. That said, I'd use two disks for a RAID 1 system partition, and the remaining disks as a RAID 5 array for your storage groups.
 
 
 

RAID 1/0 or RAID 5?

Post by Oliver Moa » Sun, 07 Jun 2009 01:43:22

Also I presume this is for the database only? It is best practice to have
the Logs and Database on seperate RAID disksets - for recovery purposes.

Oliver
 
 
 

RAID 1/0 or RAID 5?

Post by Gre014 » Sun, 07 Jun 2009 03:54:37

On Jun 5, 12:43m, "Oliver Moazzezi [MVP]"


That's another question I had. I've done some research but still have
questions.

We are going to install on a Dell 2950 with 16 GB Ram, 5, 300 GB
drives and 2, 2.5 GH Quad Core processors. Going to install on Windows
Server 2008 64 bit.

1. We have one domain controller currently. Will this server be a DC
as well? Is it required?

2. I wanted to put this server on a DMZ off of our firewall. It would
have a private 172.30.1.X address while all users and the DC would use
10.0.5.X. Our firewall would NAT the 172.30.1.X address to a public
address. This is how our current email server is setup, non microsoft
product. Woud this config work?
 
 
 

RAID 1/0 or RAID 5?

Post by Andrew Hod » Mon, 08 Jun 2009 07:06:23

On Fri, 5 Jun 2009 11:54:37 -0700 (PDT), Gre0145




We just finished a similar migration to you.

A couple of points about that config:

Where is the OS/programs going to be installed (it is best practice to
have it separate from data/logs storage).
It is also best to have log storage separate from the databases.

We went with a PE 1950 with 2 quad-core processors, with RAID-1
mirrored disks for the OS, and 8GB of RAM (will probably upgrade to
16GB).

We purchased a MD1000 drive enclosure for this and have in the
enclosure 7 300GB drives - 4 of which are RAID-10 for the data volume,
2 are RAID-1 for the logs and 1 is a global hot spare.

All roles on one server (except for edge obviously).

Have you looked into redundancy?

It is best not to make the server a DC - it needs to be a domain
member though. Depending on your user base/requirements have you
looked into Small Business server or Essential Business Server? If
you are adding Exchange into the mix with the current configuration I
would also recommend a second domain controller, because they are
essential for Exchange operations.

This was how our previous system worked also, and it isn't really a
supported configuration in the Exchange 2007 space. The Exchange
servers need to be on the same side of the network as the domain
controllers (no firewall between them). The only server that is
allowed on the DMZ is the Edge server, and if you like us have a
policy of only allowing publishing external resources on the DMZ side
(not allowing to publish internal servers), then you may need to
invest in something like ISA 2006 to publish the POP3, IMAP, HTTP etc
from the Exchange server to the external interface on the ISA box, and
thus to the DMZ of the firewall.

Thanks.
Andrew.
 
 
 

RAID 1/0 or RAID 5?

Post by Ed Crowley » Mon, 08 Jun 2009 10:20:26

Comments inline below.
--
Ed Crowley MVP
"There are seldom good technological solutions to behavi *** problems."
.



On Jun 5, 12:43 pm, "Oliver Moazzezi [MVP]"


That's another question I had. I've done some research but still have
questions.

We are going to install on a Dell 2950 with 16 GB Ram, 5, 300 GB
drives and 2, 2.5 GH Quad Core processors. Going to install on Windows
Server 2008 64 bit.

1. We have one domain controller currently. Will this server be a DC
as well? Is it required?


2. I wanted to put this server on a DMZ off of our firewall. It would
have a private 172.30.1.X address while all users and the DC would use
10.0.5.X. Our firewall would NAT the 172.30.1.X address to a public
address. This is how our current email server is setup, non microsoft
product. Woud this config work?
 
 
 

RAID 1/0 or RAID 5?

Post by Ed Crowley » Mon, 08 Jun 2009 10:22:39

or 125 users it really doesn't matter that the logs be on a separate
physical volume than the operating system, but I would recommend
partitioning the OS disk into two and putting the logs separate from the OS
so that if they grow too large due to missed backups or something it doesn't
take the entire server down.

Full redundancy for Exchange 2007 requires four servers, which is kind of
pricey for 125 users.
--
Ed Crowley MVP
"There are seldom good technological solutions to behavioral problems."
.

"Andrew Hodgson" < XXXX@XXXXX.COM > wrote in message
news: XXXX@XXXXX.COM ...

 
 
 

RAID 1/0 or RAID 5?

Post by Ed Crowley » Mon, 08 Jun 2009 10:23:26

I would recommend a RAID-1 pair partitioned into two, one for the OS, one
for the logs, and a RAID-5 set for the databases.
--
Ed Crowley MVP
"There are seldom good technological solutions to behavi *** problems."
.
 
 
 

RAID 1/0 or RAID 5?

Post by Gre014 » Wed, 10 Jun 2009 21:06:56


So how about this. 2 RAID arrays

1 Array will use 2 300 GB disk. RAID 1/0 for a total of 300 GB space.
OS and LOGS on this array.

1 Array will use the other 3 disk. RAID 5 for a total of 600 GB space.
Databasees on this array.

Again, we will only have about 50 users using Outlook, the rest will
use Outlook Express, which, correct me if I'm wrong will save space
since Outlook Express uses POP3 and pulls email off the server.

Does this sound like an OK config for what we need?
 
 
 

RAID 1/0 or RAID 5?

Post by Oliver Moa » Thu, 11 Jun 2009 00:56:20

Hi,

That would work yes. I would the same seperation of Logs and Database with
the sacrifice of the OS having to be the same partition as the Logs is fine.

Not everyone can afford lots of disk.

Oliver
 
 
 

RAID 1/0 or RAID 5?

Post by Ed Crowley » Fri, 12 Jun 2009 15:38:34

That disk arrangement should be just fine.

Using Outlook Express as your client is an awful waste of an Exchange
Server.
--
Ed Crowley MVP
"There are seldom good technological solutions to behavi *** problems."
.








So how about this. 2 RAID arrays

1 Array will use 2 300 GB disk. RAID 1/0 for a total of 300 GB space.
OS and LOGS on this array.

1 Array will use the other 3 disk. RAID 5 for a total of 600 GB space.
Databasees on this array.

Again, we will only have about 50 users using Outlook, the rest will
use Outlook Express, which, correct me if I'm wrong will save space
since Outlook Express uses POP3 and pulls email off the server.

Does this sound like an OK config for what we need?
 
 
 

RAID 1/0 or RAID 5?

Post by Gre014 » Sat, 13 Jun 2009 01:03:49


It absolutely is. Again we will have 50 users using Outlook but the
rest of our staff will use Express. Wasn't my call to implement
Exchange, but is my responsiblity to get it up and running.
 
 
 

RAID 1/0 or RAID 5?

Post by David Barn » Wed, 17 Jun 2009 07:58:14

Sorry, can't help but reply..

Mirroring (RAID 1) does not add any error checking, save that which the
drive provides.
Some RAID cards read just from a "Master" drive and some read from either
drive, whichever is nearest. This last option greatly improves read
performance almost to the levels of RAID-0 (Stripe). If a RAID card did read
BOTH drives and compare the data (the safest option) it would only be as
fast as a single spindle and in fact the latency added by the RAID card
would most likely detriment performance.
Data read errors can (and do) compute good CRC inside the drive and the
resultant "Garbage" is sent to the system as good.
Whatever application is reading that data will suddenly see NTFS CRC data
validation errors.
Woops..
AND.. because the drive didn't fail, the good data on the other spindle is
*** all use to you, because it's too late now when you have 'database'
systems like SQL and Exchange.
And anyway if the exchange store stopped (as cleanly as it could).. how do
you tell WHICH drive it was??

I have seen Gigs of exchange data disappear in this way on Compaq 5200, LSI
Megaraid (HP & DELL versions) all with top line HP, Compaq and Seagate SCSI
drives.. Ok so the exchange server was sending/recieving over 3GIG of e-mail
per day !!! yep.. 14-day averages on the SBS report in excess of 42GB.. All
that on priv & pub running at about 40GB each..


If you use RAID-5 the raid card VALIDATES the data read from the drives
before passing to the O/S.

Mathematically RAID-5 on 4 spindles SHOULD be faster than RAID-1.. In
theory.. assuming the data validation for RAID-5 occurs in real-time (ie the
raid card processor is fast enough).. only because with Mirroring you have
the read throughput performance of 2* the native drive throughput speed and
in raid-5 it 'should' be 3* the native drive throughput speed. IF the RAID
card performance was NOT part of the consideration then RAID-5 on 5 drives
will yield 4* native drive read/write performance, roughly about equivalent
read speed [on paper] to RAID-10 on 4 drives [RAID-10 write performance will
be slower as it will be 2* drive write speed] - but this is all theory
ASSUMING the RAID card does not differentiate or impact the throughput.

Battery backed Write cache (as big as possible) substantially improves
performance beyond these RAID level choices.

So the real question is how valuable is your data.. Can you take even the
smallest chance that a multi-sector read error will CRC compute good in the
drive and thus throw garbage back at exchange? Especially in these days of
massive capacity drives where the track/sector density is being pushed to
it's limits.

Just my HO..
David Barnes
 
 
 

RAID 1/0 or RAID 5?

Post by John Fullb » Thu, 18 Jun 2009 00:30:14

AID 5 generally READS faster than RAID 10. The problem is that it WRITES
far slower. RAID 10 has a write penalty (the number of operations required
for a write) of 2. RAID 5 has a write penalty of 4. In today's Exchange
2007 environments, the read/write ratio is about 1:1 (with cached clients
you can expect only 53% of IO operations to be reads, the other 47% are
writes). With 12 15K SCSI spindles, RAID 10 can produce about 1600 IOPS
under such a workload; RAID 5 is only capable of about 800 IOPS under the
same workload. That's the problem with RAID 5.



"David Barnes" <david at bitsolve dot c o m XXXX@XXXXX.COM > wrote in message
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