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hbianchi

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I have a problem of KMS becoming "frozen" for a ehile (2 to 5 minutes) when someboy publishes in a public folder, a mail with "big" attachments (5 Mb or more) in it at peak hour (when most of users are connected mostly with webmail).

When this happens, the Administrator - Opened Folder window show this "public folder as taken by hundreds of users (it beguns growing as soon as email is issued and continues growing reaching several hundreds. In fact I saw more than 380 users a "having the public folder taken"). Suddenly, the folder relases all connections and everything becomes stable again. More big is the attachment, more it takes to return to stable condition.

This happens since several releases, and I heve been reporting this to support without solution. Now I have the problem completely isolated but I want you to know if somebody has similar problems. Sinde it happens we have ocmpletely changed hardware and software. We passed from a Dual Core Pentium rpocessor with 4 GB RAM and 2 x 300 GB HD running windows 2003 Server, to a Dual Processor Quad Zeon (8 processors in total), with 8GB RAM and 2 x 160 GB RAID 1 HD array for O.S. and KMS and 5 x 1 TB RAID 5 HD array for Mailstore and only noticeable change after that is: with the previous one we got KMS crashes when it happened (at that time we didn't know it was related to big attachments), and now we have the system frozen for a while but not crashes.

We run a 660 users installation, most of them using Kerio webmail, and just a few ones using KOC or MAC Mail.


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scottwilkins

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This is a general problem between computer design and Kerio's methodology. Basically the write to 660 users is clogging up the works in your case.

My experience with Kerio has shown that their storage methodology is not perfect, but I've found it to be very easy to administrate in some cases. Basically a give and take situation. I've also found that a powerful computer is not really that benificial. I'm running only 100 users on an older single CPU Xeon dual core, and normally utilize only 5% CPU, and never go above 25% CPU. That and memory usage is always below 1 gigabyte. Disk usage though, is a totally different story. My disk usage is above 80% during most of the workday. And a lot of the time at 100%. Kerio's methods just require a lot disk performance and almost no CPU/Memory performance.

I've considered creating my next Kerio server with the newer SSD drive technology. But, I'm not sure about how well SSD drives will work for longevity yet. So for now what I've thought of for my next server is a SAS Raid setup with a very very large cache. With this setup, I'd expect to see a tremendous performance jump. But until tested that's just a guess.

Anyway, that's my 2 cents worth...

Scott
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My IT Indy

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Scott,

Have you seen this video using SSD in a raid?

http://www.youtube.com/watch?v=96dWOEa4Djs

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

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HoosierMac,

Yep, after drooling from watching that video I purhcased an SSD drive for my laptop. After owning one, I'd say that SSD drives still need some maturity before they are ready for heavy server use like an e-mail system. So, in the mean time I'm thinking a high end SAS RAID 0 or 5 or 10 with at least 1 gig of cache would make a world of difference in Kerio's drive hungry methods. The large cache may give a close to SSD performance feel to such a system.

The key would be the RAID card. Something like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16816151 048

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My IT Indy

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Yikes, that card looks intense. It better be for the price.

I'm debating about upgrading a client's storage and can't see how SSD's justify the cost for RAID at this point, especially if they detonate and take our data with them. I wonder if just throwing more SATA drives at the situation would alleviate our slowdowns vs. faster drives.

16 sata drives would have a pretty nice seek time vs. 8 sas or ssd drives. And the cost would be a LOT less.

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