SSD = Superfast IMAP4

[HVGS]

Our Ability Mail server supports over 1200 users and regularly handles 140 IMAP4 concurrent clients. Since upgrading to 2.70 we noticed IMAP4 performance to degrade massively and also mailing lists to take forever to process.

We did some checks on the server with perfmon and %disk time was peaking over 900 at times and sitting on 100 for long periods.......Microsoft recommends 20 to 30 max !!

The server was a P4 3.2 - 1GB RAM - 200GB SATA Hard Drive (installed 2005)

We upgraded the server last weekend to

Xenon X3470 - 4GB DDR3 - 256GB X256 Corsair Extreme SSD drive

The performance difference on the SSD in unbelievable. IMAP4 is faster than ever. %disk time rarely is over 0 and peaks to 10
The faster CPU does help but it's the SSD that makes the difference. Ability stores emails in separate files and the next to zero seek time of the SSD is the key.

Hope this may help someone having similar performance issues.


Phil

[rob]

Thanks for the feedback on SSD disks, this isn't something we have tested ourselves but of course we have watched them develop in the industry for the last couple of years. Glad to hear they have had such a postive impact on your server.

[mcknet]

I bet the increase in RAM has a lot to do with the performance, too. I've seen a performance increase going from 2gb to 3gb on a virtual server. 2gb just barely wasn't enough while 3gb was fine. With the numbers you're talking about, I'd guess 1gb of RAM was the biggest problem. 4gb probably made it possible to cache enough data so that it doesn't have to wait for the drive very often. SSD drives are very nice, though!

[HVGS]

No it's all to do with the SSD (IMAP4 is very disk intensive and Ability does not use a database message store)......even under full load Ability does not need more than 1GB of ram on the box. We did a lot of testing before spending $1000 on an SSD to fix the issue.


Regards,
Phil