RAID on Exchange


We are only a small business but are expanding quickly and have more users on board these days.  I currently have a Dell 1600 for my Exchange 2003 server, configured with two 36Gb disks.

Disk 0: OS, Logs
Disk 1: database

Now I want to go about adding some fault tolerance to my disks, so am thinking of purchasing another two 36GB disks and setting up software RAID-1 using Windows.

1)Does anyone have any tips\best practices or word of caution before I look at doing this ?  
2) This shouldn't affect performance of the Exchange database should it, as RAID-1 improves Read speed ?

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A better way might be to make a full backup, blow them away, put in your new disks, and make them all hardware RAID 5.  Then do a restore to your new RAID 5 array.  That'd probably be best.  Software RAID will impact performance as the OS must do the work rather than a RAID card.  However, it's debatable how much of an impact there will be.  Some will say not much, some will say alot.  Depends greatly on how the server is used and the expected load.  For Exchange, I wouldn't use software RAID, but that's me.

As far as a word of caution, I have none.  Your planned upgrade should be pretty straight forward.  Just make sure you have a full backup ready to go in case of an unforseen disaster.

I do recommend using hw RAID instead of sw. As for the RAID 5 comment, if you do that and you loose your RAID set then all of you data is toast. You are much better to use RAID 1 for both the DBs and the TLs.

The performance will depend on the things that thernlund mentioned as well as the speed of the drives. Spindle speed is a key in Exchange. If you can get 15k drives, then they will give you better performance over 10k drives.


This is a good article on raid level differences with Exchange.  My company uses Raid 0+1 because for me fault tolerance is more important than speed, and hard drives dying is not a question of if but of when.
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Hardware Raid is always the best route to go however in a small business cost always plays a factor.

The best practice for Exchange is to put your Logs on Raid 1 due to the way the logs are written sequential and put your database on Raid 5 since it is written radomly.

However in a small envrionment you probaly will not see any real performace gains but you must also look at long term planning for growth.

I alway try to steer people away from Software based raid however if the budget will only allow it then that is the route you take. I would verify that you have a full backup of you Exchange data then add the second drive and configure the raid (software) which will automatically copy the disk for the mirror.

stevendunneAuthor Commented:
Hi guys,

I finally have the disks after the first set of disks sent out to me were incorrect.  The drives are 36GB 80pin 15,000 rpm.

We are only a small business and have 25 users on our Exchange 2003 server.  I'm going to configure the disks as follows:

Disk 0: OS, Logs (Mirror to Disk 2)
Disk 1: Database (Mirror to Disk 3)

Do I need to setup the volumes or does this happen automatically when the mirroring starts ?
Do I need to stop any services (information store) when adding the mirror in ?
I am assuming that you are configuring this mirroring through Logical Disk Manager and not through hardware or other 3rd party software.  

LDM is located @ Admin Tools -> Computer Management

LDM will show you a graphical representation of the data on your disks.

A comprehensive guide can be found on microsofts website.

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