[qmailtoaster] Re: Imap and Memory Issue
You should be able to run many more users than you have on that gear (I would guess over 10x as many). As a side note, as Bharath indicated, 6G of your ram is being used for disk caching. This is a behavior of linux that's commonly misunderstood. If the kernel has ram left over after loading all of the processes it's running, it uses whatever remains to cache disk i/o. So the numbers indicate that there's no free space, which there isn't, because there pretty much never is (or never should be). The size of the cache gives you a rough idea of how much is not being used by processes though. Typically, you should have some cache, but you don't necessarily need a ton of it. Depends on the services being run. You could probably get by with half the ram you have without noticing any performance degradation (I'm guessing). So back to tuning this beast. Which version of dovecot are you running, and please post your configuration. There's a handy dovecot command which will output all of the non-default parameters you're using. Please use this to post your config (I don't recall the command off hand). Are you seeing any performance issues aside from what you've observed regarding memory use? -- -Eric 'shubes' On 09/06/2012 10:50 PM, Amit wrote: Yes on the server NTPD service is running. Total No. of Email Ids: 127 Total No. of IMAP Users: 75 Amit -Original Message- From: Eric Shubert [mailto:e...@shubes.net] Sent: Friday, September 07, 2012 6:48 AM To: qmailtoaster-list@qmailtoaster.com Subject: [qmailtoaster] Re: Imap and Memory Issue On 09/06/2012 12:34 AM, Bharath Chari wrote: Amit a...@ikf.co.in wrote: Hi Everyone, Last month I upgraded my server hardware and migrated QMT from old server to new server, but after up-gradation I started facing problem in Outlook. My users Outlook automatically goes into offline mode. All 100 users are on IMAP. Differences of Old and new scenario mentioned below: OLD Server Hardware: Intel Core2Quad, 2 GB RAM, 250 GB HDD * 1 No Software: CentOS 5.4 32 bit, QMT 32 bit and Dovecot 32 bit NEW Server Hardware: Intel Xeon E5620 processor, 8 GB RAM, 2 TB * 2 No HDD (RAID 1) Software: CentOS 5.8 64 bit, QMT 64 bit and Dovecot 64 bit I also noticed on new server that RAM utilization going very high. Attaching screen shot of the same below: Kindly let me know if any further details required. Thanks, Amit Hi Amit, At first glance your memory usage seems OK. You have approx 6GB of ram as cached. Is your new server set to sync time with an ntp server? Dovecot is very sensitive to drift in clocks. Bharath - Good suggestion, Bharath. That didn't occur to me off hand. That's a honker of a host, Amit. Care to share numbers? Like number of users, emails. -- -Eric 'shubes' - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com
Re: [qmailtoaster] Re: Imap and Memory Issue
On Friday 07 September 2012 11:20 AM, Amit wrote: Yes on the server NTPD service is running. Total No. of Email Ids: 127 Total No. of IMAP Users: 75 Amit -Original Message- From: Eric Shubert [mailto:e...@shubes.net] Sent: Friday, September 07, 2012 6:48 AM To: qmailtoaster-list@qmailtoaster.com Subject: [qmailtoaster] Re: Imap and Memory Issue On 09/06/2012 12:34 AM, Bharath Chari wrote: Amit a...@ikf.co.in wrote: Hi Everyone, Last month I upgraded my server hardware and migrated QMT from old server to new server, but after up-gradation I started facing problem in Outlook. My users Outlook automatically goes into offline mode. All 100 users are on IMAP. Differences of Old and new scenario mentioned below: Hi Amit, At first glance your memory usage seems OK. You have approx 6GB of ram as cached. Is your new server set to sync time with an ntp server? Dovecot is very sensitive to drift in clocks. Bharath - Good suggestion, Bharath. That didn't occur to me off hand. That's a honker of a host, Amit. Care to share numbers? Like number of users, emails. -- -Eric 'shubes' Are you able to connect to IMAP from localhost? Or using webmail (on the same/different host)? If you are, then the problem lies elswhere, and you may need to check your firewall settings. Do you have iptables running on the server? If you are connecting via SSL on the Outlook clients, there could be (I'm just shooting in the dark here - not too familiar with Outlook) with certificates from the old server being cached. Bharath - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com
[qmailtoaster] Re: Imap and Memory Issue
On 09/07/2012 07:12 AM, Bharath Chari wrote: Are you able to connect to IMAP from localhost? Or using webmail (on the same/different host)? If you are, then the problem lies elswhere, and you may need to check your firewall settings. Do you have iptables running on the server? If you are connecting via SSL on the Outlook clients, there could be (I'm just shooting in the dark here - not too familiar with Outlook) with certificates from the old server being cached. Bharath I might add that Outlook'03 does not support TLS. If you want to use SSL with Outlook'03, you'll need to set up port 465 for submissions. Dovecot should handle SSL (port 993) just fine though (provided it's configured). FWIW, I hope to get port 465 support included in QMT soon. Note, it will be disabled by default though, as it's not a recommended configuration. I realize that this -- -Eric 'shubes' - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com
RE: [qmailtoaster] Re: Imap and Memory Issue
I'm using the latest version of Dovecot install using QTP Server. From yesterday no hanging issues observed but still monitoring the same for next few more days. Yes I had got confused regarding caching of RAM, but now it is clear. Thanks. Will update back if found with some issues. --Amit -Original Message- From: Eric Shubert [mailto:e...@shubes.net] Sent: Friday, September 07, 2012 7:57 PM To: qmailtoaster-list@qmailtoaster.com Subject: [qmailtoaster] Re: Imap and Memory Issue On 09/07/2012 07:12 AM, Bharath Chari wrote: Are you able to connect to IMAP from localhost? Or using webmail (on the same/different host)? If you are, then the problem lies elswhere, and you may need to check your firewall settings. Do you have iptables running on the server? If you are connecting via SSL on the Outlook clients, there could be (I'm just shooting in the dark here - not too familiar with Outlook) with certificates from the old server being cached. Bharath I might add that Outlook'03 does not support TLS. If you want to use SSL with Outlook'03, you'll need to set up port 465 for submissions. Dovecot should handle SSL (port 993) just fine though (provided it's configured). FWIW, I hope to get port 465 support included in QMT soon. Note, it will be disabled by default though, as it's not a recommended configuration. I realize that this -- -Eric 'shubes' - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com - To unsubscribe, e-mail: qmailtoaster-list-unsubscr...@qmailtoaster.com For additional commands, e-mail: qmailtoaster-list-h...@qmailtoaster.com
