RAID Configuration suggestions for Exchange 2003

Hello everyone,
I am about to completely rebuild one of my servers with Server 2003, and I am going to deploy Exchange 2003 upon this server.  My question is what are your recommendations as far as RAID Configurations, for a Standalone Exchange 2003 Server, which will be service approximately 1000 users.  The Server is a Dell Power Edge 2850 with 4 250 gig drives.  I realize that this may indeed be and Exchange topic question, but in my mind it fit both arenas.  Any guidance would be greatly appreciated.  Thank-you.
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Jandakel2Asked:
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Lee W, MVPTechnology and Business Process AdvisorCommented:
With only 4 drives, I'd set it up as a RAID 5.  If you could add another drive, I'd do a RAID 1 split between OS and Exchange Logs and a RAID 5 for the information stores.  

You could consider a RAID 10, but with 1000 users, I'm not sure you'd have enough space.  (RAID 10 will leave you with 500 GB usable).
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Jandakel2Author Commented:
Thanks,
I'm leaning toward the standard RAID 5, using the 4 disks, and throwing on another drive outside of the array for the pagefile.  What are your recommendations for partition sizes?  I plan on having a partition for the system, one for the Information Store and one for the Logs....
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Lee W, MVPTechnology and Business Process AdvisorCommented:
That would be about right, partition wise.  I was in a question that established that the page file on the seperate disk was optimal, but frankly, I don't see it providing THAT much benefit.  I'd spend the money on Physical RAM - the more RAM, the less paging needed.
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Jandakel2Author Commented:
I have 6 gig RAM so that won't be an issue.  I beefed up when spec'ing the server.  So, with 4 250 gig drives, I theoretically have, what, 750 gigs addressable?  So, saying that statement is correct, what are recommendations for the actual partition sizes, if I was to go with 3 partitions: 1 for OS  1 for Information Store  and 1 for Logs?
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rindiCommented:
I agree with leew, but would generaly suggest you get more or bigger HD's. With 1k users you'll probably reach the limits soon. You may also be getting problems with access speed, for which raid 10 would be best.

The system shouldn't need more than 10 GB, the rest is difficult to say as it depends on the traffic you get and how your users use exchange.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
OS doesn't need much - Dell defaults to 12 GB for SBS and I think that's perfectly reasonable.  I would probably leave 88 GB (to make an even 100) for the logs, leaving 650 GB for the infromation store.  As long as you do periodic backups of Exchange, the log file should get cleared and leave you with 88 GB for the log being plenty of space.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
More space for the users would be better and RAID 10 better still... consider that with this plan, you have 650 MB per user.  Problem is, the 2850's, if I remember correctly, are 2U boxes with a max of 5 drives using a sled in a 5.25 bay.  So, using RAID 5 the best you'd get is an allocation of 1 TB of space and probably 900 MB per user... maybe 850 MB.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
You could also add an external SCSI storage array later, but I've not been a fan of Dell's external SCSI arrays - maybe they got better, but the 200,210,220Ss all proved flawed to me when I was using them a few years ago.
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Jandakel2Author Commented:
Thus far, I have liked the idea of the RAID 1 for the OS and the logs and the RAID 5 for the Information Store, after adding an additional drive.  I am implementing this server in a K-12 school district, so I don't need to be too crazy about performance.  It is however, very important that the fault tolerance and the disaster recovery measures are in place.  I have already tried putting Exchange up in a test environment, and my biggest problem was running out of space due to ridiculous log sizes and amounts.  This was with the default configuration, so I want to leave room to compensate for this when I rebuild and reconfigure this go around.....Thank you very much for the feed back.
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Lee W, MVPTechnology and Business Process AdvisorCommented:
If you are performing backups (online backups), the logs are cleared so space for them should not be an issue.

Excerpt from:
http://www.petri.co.il/backup_exchange_2000_2003_with_ntbackup.htm

"Online Backup - An Online backup is performed while the Information Store is still mounted and the Exchange server is operational. The Exchange is Online and available for transactions, therefore it still allows users to work without interruption. Online backups also automatically clear the database logs upon completion."
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Jandakel2Author Commented:
Yes, you are exactly right about the necessity of the backups.  This was one of the things I learned during my trial.  Here is another interesting scenario that I have just read about.  OS RAID 1, Logs RAID 1, Database 0+1.  This doesn't sound bad, accepting that the RAID 1 just for the Logs seems to be a bit of an over kill, given the use of 250 gig drives.......your thoughts?  Thanks again
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rindiCommented:
Database 0+1 is similar to raid 10 like we suggested already. This needs 4 or more drives for the store alone which might give you problems if leew is correct with the limited space for that server.
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David_FongCommented:
1000 users on 4 disks? MS say 0.18 iops per light user with small mailbox, so maybe 120 read and 60 write = 460 iops in RAID 5 and that's not counting the OS or transaction logs or paging since the MS way would have these on seperate spindles. Even in RAID 1 you'd need 240 iops. 15K disks will give about 150 iops each but you're still pushing it. I would think about getting more disks unless they're very light users.

http://www.microsoft.com/technet/prodtechnol/exchange/guides/StoragePerformance/f4dc0eaf-3d21-4650-83b7-86526694f05a.mspx?mfr=true

>ridiculous log sizes

Someone hasn't been backing up, that truncates the log files. You could turn circular logging on though, with the logs on the same disks as the data it's not so important to have a logfile to play back since that will probably fail if the database fails anyway.
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Jandakel2Author Commented:
Thanks for the suggestions everyone...appreciate it.  Any other advice is welcomed, as I am planning on leaving this question opened for a while until I have all the information I need.  After I have, I will evaluate who has provided the most info and give them the points.  LEEW you're in the lead as of right now!! Thanks again for the advice all.
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pgm554Commented:
A 1000 Exchange users on 1 box?
 No way,it's not Groupwise or Sendmail.
Think 250 to maybe 500 users (MAYBE).
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Duncan MeyersCommented:
>The Server is a Dell Power Edge 2850 with 4 250 gig drives.

Are you sure? These are surely either 146GB or 300GB drives.

David_Fong is right - you need more discs if you are going to make this work. You'll also need to abandon the idea of RAID 5 - it won't have sufficient write performance for that many users. I'd suggest a RAID 1/0 set for the information store and a mirrored pair for logs and OS. And I'd still have my doubts that this configuration is going to work for you.

>200,210,220Ss all proved flawed to me when I was using them a few years ago.
No change there. :-)
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Please... Exchange can EASILY handle 1000 users if it's on an appropriate box.  one of my past companies had 400 users on an Exchange 5.5 server - running on a 500 MHz CPU and 1 GB RAM and only a mirror for RAID.
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Duncan MeyersCommented:
My concern is the disc I/O load. I suspect that the current config will be marginal.
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Jandakel2Author Commented:
meyers d-
You are correct they are 146 gig drives, so that leaves me with 4 146 gig drives......so that gives me approx. 438 gig available for RAID, and even less for RAID 1+0...what....292 gig?  I am planning on only allowing Administrators and their secretaries and all Directors the ability to store all their information on the server.  The rest of the faculty will POP it down, and the student accounts will only use OWA.  That's the plan anyway.  So, in my mind technically, I should appropriate for 500 users even though there will be 1000 mailboxes....is that the right train of thought?  Thanks so much
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rindiCommented:
OWA means you'll need to store the mailbox on the server...
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GuenthaCommented:
That server will handle 1000 users just fine. I use a dell 2850 with 2 dualcore 2.8 xeons and 6gb of ram and support 1500 users. the drives are 6 73gb 10k. dont worry so much about the drive speed look more into ram size. with lots of ram there is very little paging so your drives are free to go about there business. my biggest question is why on earth do the students need 600MB mailboxes. this is several thousand messages. my users have 200MB mailboxes and that is still serveral thousend messages. only my executives and marketing deparments get bigger mailboxes. and that is easly acomplished with a different mailbox store. also check into connection speed I have noticed performance boosts up until 4GB agregate connection. I moved to a 6GB agregate connection for a while but saw no improvments. even if you are still on a 10/100 network wich by you school coment I would imagen you are run serveral conections in agregate mode to stop the network from being a bottleneck.
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Jandakel2Author Commented:
Leew-
Thanks for the continued support on this question, greatly appreciated.

JK
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