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gogy

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We are using Kerio MailServer 6.6.2 via Outlook (IMAP, without offline caching). There are 80 users.

The following are the server characteristics:
CPU: Intel Core 2 Quad Q9400
RAM: 4GB
HDD: soft RAID5 (3 hdd's)
OS: MS Windows 2003 R2, 32bit

We have serious problems with performance - often, if the user just change folder, outlook freezes for half of minute.

I included screenshot from performance monitor, it could be helpful. As I can see, there could be a problem with hdd, but isn't raid5 enough for this kind of server?

  • Attachment: perf.gif
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[Updated on: Mon, 27 July 2009 09:41]

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sedell

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RAID 5 is pretty slow because of the overhead. I see more and more disk intensive server products listing RAID 5 as unsupported because of that. You'd be better off adding a disk and going with RAID 10.

Something else I've found helps with KMS, because of the nature of the file based mail storage, is regular defrags. I have one scheduled to run every week during a low activity time. Performance was noticeably better after the first one completed, especially when we were still on slower hardware.

Scott
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My IT Indy

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What kind of hard drives are you running? How many users do you have? What size mailboxes?

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My IT Indy
Kerio Certified Reseller and Hosted Provider
http://www.myitindy.com
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gogy

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HDD's are 3 x Hitachi SATA 320GB, 7200rpm, 16MB cache.

There are 80 users.

Size of mailboxes vary a lot, but complete store size is aroung 60GB.

At this moment, I plan to extend storage configuration to 6 hdd's in raid10. I hope this will help. Still, it is sad to hear that this mail server requires so much storage power. It seems it is not too scalable...
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My IT Indy

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KMS's mailstore is not a database, it's a nested file system. Each email/contact/calendar item is a separate file located in the mailstore. KMS is VERY scalable, you just need appropriate hardware for it. The raid array you're using is not designed for this type of workload, raid 5 isn't bad, but 3 drive raid 5 arrays are not that fast at all.

Storage is pretty inexpensive now, I think what you spec'ed out should work just fine for your needs. If you can afford SAS drives I would go with smaller/faster SAS drives vs. SATA.

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My IT Indy
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http://www.myitindy.com
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gogy

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Unfortunately, SAS drives means a lot of new harware so it is not an option for now, I hope 6xhdd in raid10 will be suitable at least for 2 years :-||

BTW at this moment we are using KOC without offline caching. Do you recommend us to use KOC with offline caching to gain additional performance?
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steven

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from my experience, moving from KOC to KOFF moves speed issues away from your server to your clients.

the server will be more relaxed, but if the clients use older hardware, those computers will be the new bottle neck
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My IT Indy

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KMS really depends upon IO transaction speed. Raw throughput on a disk array doesn't really matter so much as low seek times and low latency. I've had better experiences running KMS on slower processors/less ram and faster disk arrays than faster CPU's/ more ram, and slower hard disks.

Having said that, you should be fine with what you spec'ed out.

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My IT Indy
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winkelman

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HoosierMac wrote on Tue, 28 July 2009 02:35

KMS really depends upon IO transaction speed. Raw throughput on a disk array doesn't really matter so much as low seek times and low latency.


True. Many years ago I migrated Kerio from a RAID-1 7.200rpm PATA array to a RAID-1 15.000rpm SCSI array and KMS's performance at least quadrupled. The SCSI disks are obviously much faster, but SCSI (or SAS) is also inherently somewhat better at concurrent I/O requests.

RAID-10 would indeed be somewhat faster that RAID-1, but for many small file I/O's (suchs as KMS uses most) the benefit of RAID-10 over RAID-1 is not that great (latency is not lower), I guess. Anyway, my 1U server could only take 2 disks Cool.
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cthomas

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> Something else I've found helps with KMS, because of the nature
> of the file based mail storage, is regular defrags. I have one
> scheduled to run every week during a low activity time.
> Performance was noticeably better after the first one completed, > especially when we were still on slower hardware.

Can this be done with KMS running or is it advisable to shut down the server while a defrag runs.

- C. Thomas
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winkelman

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cthomas wrote on Mon, 03 August 2009 19:42

>
Can this be done with KMS running or is it advisable to shut down the server while a defrag runs.


No, defragging can be done whilst KMS is running. Of course, it will slow the server down, so it's best to schedule the defrag at night.

KMS has a tendency to fragment the file system really quickly, so I used to defrag the server daily. After some years I've now decided that defragging one a week is still enough. I've tested is, and the defragger is still capable of fully defragging the disk in one run (takes 3.5 hours in my case).

I simply schedule the standard built-in Windows defragger (via the command line) with the Windows Task Scheduler. I did some batch-file things so the defragmentation report is emailed to me at the end of the defragmentation.
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mrralan

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Can you share that .bat file please?

winkelman wrote on Tue, 04 August 2009 12:23

cthomas wrote on Mon, 03 August 2009 19:42

>
Can this be done with KMS running or is it advisable to shut down the server while a defrag runs.


No, defragging can be done whilst KMS is running. Of course, it will slow the server down, so it's best to schedule the defrag at night.

KMS has a tendency to fragment the file system really quickly, so I used to defrag the server daily. After some years I've now decided that defragging one a week is still enough. I've tested is, and the defragger is still capable of fully defragging the disk in one run (takes 3.5 hours in my case).

I simply schedule the standard built-in Windows defragger (via the command line) with the Windows Task Scheduler. I did some batch-file things so the defragmentation report is emailed to me at the end of the defragmentation.

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winkelman

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Sure. It's actually 2 batchfiles (this is needed to be able to capture the actual defraggers screen output to a file and email it).

The following is to defrag the C-drive, but is is easily adaptable for other drives as well of course.

I use 'Blat' (www.blat.net) as a command line email sender (attached to this post).

So place the following two batch files and the 'Blat' files into a single folder and call the 'defrag-c.bat' to do the defragging (not the '...actual.bat' file).

Note: you'll have to change the 4 variables set in the first batch files to your needs (TO and FROM email address, subject and SMTP server).

You'll have to replace the several <_a.t_> with the real 'at symbol', this site won't allow real 'at signs'.

defrag-c.bat
<_a.t_>ECHO OFF

REM batch file created by Feike Winkelman, 5 September 2007

REM Run this batchfile to defragment the drive and receive a
REM defragmentation report by email.

REM IMPORTANT: set the following parameters correctly

REM Make sure to enclose everything containing spaces in double-quotes (" ")!!!
REM Email addresses can be full addresses ("Full Name <email<_a.t_>domain.com>")

REM ======================================================================

SET DEFRAG_SCRIPT_EMAIL_TO="Defragmentation reports <defragmentation-reports<_a.t_>domain.com>"
SET DEFRAG_SCRIPT_EMAIL_FROM="Defrag-script <no-reply<_a.t_>domain.com>"
SET DEFRAG_SCRIPT_EMAIL_SUBJECT="COMPNAME C-drive defragmentation report..."
SET DEFRAG_SCRIPT_EMAIL_SMTP_SERVER=10.20.30.40

REM ======================================================================


REM The actual work is done next:



REM Deleting previous defragmentation log (if it exists)
IF EXIST defrag-c.log DEL defrag-c.log

ECHO ---------------------------------------------------
ECHO Starting defragmentation of C-drive
ECHO Output send to file 'defrag-c.log'
ECHO ---------------------------------------------------
ECHO.
ECHO.
ECHO Defragging C-drive now...

CALL defrag-c-actual.bat > defrag-c.log

ECHO ---------------------------------------------------
ECHO Defragmentation finished
ECHO Output stored in file 'defrag-c.log'
ECHO ---------------------------------------------------

ECHO.
ECHO Sending defragmentation log by email
ECHO ---------------------------------------------------
ECHO.

REM Sending the defragmentation report by mail
blat.exe defrag-c.log -to %DEFRAG_SCRIPT_EMAIL_TO% -f %DEFRAG_SCRIPT_EMAIL_FROM% -s %DEFRAG_SCRIPT_EMAIL_SUBJECT% -server %DEFRAG_SCRIPT_EMAIL_SMTP_SERVER%

ECHO ---------------------------------------------------
ECHO Email sent
ECHO ---------------------------------------------------


REM Clear the perviously set environment variables

SET DEFRAG_SCRIPT_EMAIL_TO=
SET DEFRAG_SCRIPT_EMAIL_FROM=
SET DEFRAG_SCRIPT_EMAIL_SUBJECT=
SET DEFRAG_SCRIPT_EMAIL_SMTP_SERVER=



defrag-c-actual.bat
<_a.t_>ECHO OFF

REM Running this batchfile will defragment the drive,
REM but it will not send a defragmentation report by email.
REM Use the defrag-x.bat batchfile if you want to receive email.

ECHO.
ECHO -----------------------------------------------------------
ECHO.
ECHO This script is running on computer %COMPUTERNAME%
ECHO.
ECHO ---------------------------------------------------
date /T
time /T
ECHO Starting defragmentation of C-drive
ECHO ---------------------------------------------------

defrag C: /V

ECHO ---------------------------------------------------
date /T
time /T
ECHO Defragmentation finished
ECHO ---------------------------------------------------

  • Attachment: Blat.zip
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[Updated on: Tue, 04 August 2009 14:58]

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