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Home » Kerio User Forums » Kerio Connect » Requesting feedback from KMS installs with >1000 IMAP users

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Note: Firstly, please do not response if you're not >1000 users or so. Server performance issues vary greatly from 80 users to 200 users to 500 users to 1000 users

1.) How many users?
2.) How's your server performing?
3.) What kind of hardware (CPU/RAM/Disk) is your KMS install running on?
4.) What OS is KMS running on?
5.) What special performance tweaks did you make on this server? (if any)
6.) Misc gripes and beefs?

I'll answer the questions:

1.) ~1400 users, probably 80% of them are using IMAP/SSL

2.) Poorly. IMAP operations are pretty slow and laggy. We're not really maxing out on CPU or RAM, either. Plenty of both are free. Disk sees good utilization, but nowhere near maxed. The mail store volume, which lies on an NTFS partition is fragmenting horribly from all the message transactions (each message is an individual file, and we have approximately ~1.5 million messages stored in IMAP folders on our KMS server)

3.) Dual xeon 2.8ghz's, 2gb ram, scsi ultra320 raid5 setup

4.) Windows Servers 2003 (although I am considering moving to Linux if it would resolve some issues)

5.) Adjusted NTFS cluster sizes and bought a copy of Diskeeper and defrag very frequently, as the mail store volume and its MFT get fragmented quickly with all the read/write/moves of email messages (files).

Also, I've offloaded spam filtering to an external unix/postfix/spamassassin box and this takes a considerable load off of our KMS box.

6.) I'm wondering if KMS can properly scale to our scenario. We've been gradually moving all our users from POP3 to IMAP/SSL over the past year or so, and KMS has been getting slower and slower. I'm worried KMS can't scale in our situation.

I'm wondering if there are any other KMS customers in our situation with as many multiple IMAP users as us.

I've saved some of the KMS admin console graphs for IMAP at the following urls. Please note that 99% of these are IMAP/SSL:

Some requests:
- Re-read the note at the top of my post before responding :)
- Post anything you feel is relevant
- Please no Kerio bashing/flaming
- Please no Windows bashing/flaming
- Please no bashing/flaming anyone

Kerio MailServer 6.7.1 w/AD
Windows Server 2003 SP 1
Dell PowerEdge 2850 (Dual Xeon 3.2ghz and 2 GB RAM)
~1300 users
~1000+ concurrent IMAPS connections
iPhone users
Outlook 2007 KOFF users
Apple iCal 10.5/10.6 users
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