Re: Scalable
On Mon, Feb 15, 2010 at 04:56:44PM +0200, Timo Sirainen wrote: On 13.2.2010, at 0.41, Victor Duchovni wrote: No, this is largely irrelevant. What matters is the IMAP performance they expect, that IMAP servers are reasonably CPU and memory intensive. From what I've seen is that IMAP servers normally take less than 1% CPU load (mainly Dovecot, but I'd think others too). Memory is more important, currently maybe 0.5 MB/connection or so for Dovecot. Usually anyway disk IO is the bottleneck. Thanks, for the correction, this makes sense. Yes the IMAP server performance will be disk (and to some extent memory) not CPU constrained. Still Postfix will not be the bottleneck. -- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note.
Re: Scalable
On 13.2.2010, at 0.41, Victor Duchovni wrote: No, this is largely irrelevant. What matters is the IMAP performance they expect, that IMAP servers are reasonably CPU and memory intensive. From what I've seen is that IMAP servers normally take less than 1% CPU load (mainly Dovecot, but I'd think others too). Memory is more important, currently maybe 0.5 MB/connection or so for Dovecot. Usually anyway disk IO is the bottleneck.
Scalable
Hi Folks, How scaleable is postfix and dovecot, using mysql for user databases, on one server? My current server has 256MB RAM (It's a VM on slicehost). How many users do you think that will handle? How much RAM/CPU would I need to host 600 users? Please remember, that due to the nature of email, I imagine that the server won't be constantly hammered. How much disk space do you think I'll need? I'm just looking for advice from someone with experience Thanks Jonny
Re: Scalable
On Fri, Feb 12, 2010 at 12:14 PM, Jonathan Tripathy jon...@abpni.co.uk wrote: Hi Folks, How scaleable is postfix and dovecot, using mysql for user databases, on one server? My current server has 256MB RAM (It's a VM on slicehost). How many users do you think that will handle? How much RAM/CPU would I need to host 600 users? Please remember, that due to the nature of email, I imagine that the server won't be constantly hammered. You'll probably find that one heavy user will take the resources of 10s or 100s of lightweight users. With only 600 users, you're not going to get a lot of averaging so you'll have to figure out what your specific users are going to need. 60 heavy users might bring the server to it's knees, 6000 light users might work out fine. It might be better to think in terms of messages per hour than number of users. How much disk space do you think I'll need? I'm just looking for advice from someone with experience Thanks Jonny
Re: Scalable
Aaron Wolfe put forth on 2/12/2010 11:39 AM: It might be better to think in terms of messages per hour than number of users. Most importantly, who are these users? Are they customers? Members of some society or club? Will these be their primary email accounts or secondary, tertiary, etc? If these are nursing home residents you could get by with an old 386. ;) Who are your users? The answer to this question will probably answer most of the others. -- Stan
Re: Scalable
On Fri, Feb 12, 2010 at 05:14:30PM -, Jonathan Tripathy wrote: My current server has 256MB RAM (It's a VM on slicehost). How many users do you think that will handle? Is more RAM substantially more expensive? 256 MB is rather meek these days. With physical servers, one typically gets 16GB or more of RAM these days. Even a 6-Watt Atom-CPU FitPC box comes with 1GB of RAM! Your machine is way off the mainstream memory curve... For Postfix alone you're fine, but for running an IMAP server with users, you are likely too cramped, ask on the Dovecot list, not here. Postfix is not very memory intensive. -- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note.
Re: Scalable
Hi Everyone, Thanks for all the comments. The reason why I said 256MB RAM, is because that is currently what my VM has... If I were to take out a dedicated server with: 2.8 Dual Core 2GB RAM how much would that handle? My customer is a business, with 600 staff, however I think they just use a single broadband connection so that will be the limiting factor, as this dedicated server has a 100Mbps link to the net.. Please let me know what you think Thanks Jonny On 12/02/2010 19:24, Victor Duchovni wrote: On Fri, Feb 12, 2010 at 05:14:30PM -, Jonathan Tripathy wrote: My current server has 256MB RAM (It's a VM on slicehost). How many users do you think that will handle? Is more RAM substantially more expensive? 256 MB is rather meek these days. With physical servers, one typically gets 16GB or more of RAM these days. Even a 6-Watt Atom-CPU FitPC box comes with 1GB of RAM! Your machine is way off the mainstream memory curve... For Postfix alone you're fine, but for running an IMAP server with users, you are likely too cramped, ask on the Dovecot list, not here. Postfix is not very memory intensive.
Re: Scalable
On Fri, Feb 12, 2010 at 4:50 PM, Jonathan Tripathy jon...@abpni.co.uk wrote: Hi Everyone, Thanks for all the comments. The reason why I said 256MB RAM, is because that is currently what my VM has... If I were to take out a dedicated server with: 2.8 Dual Core 2GB RAM how much would that handle? My customer is a business, with 600 staff, however I think they just use a single broadband connection so that will be the limiting factor, as this dedicated server has a 100Mbps link to the net.. Please let me know what you think If you want to give your client good advice, you will have to measure their mail flow in a meaningful way. How many messages per second, minute, hour, day do you need to handle? How many concurrent SMTP sessions? Do they even care if a message takes 100ms vs 100 seconds to traverse this system? Thanks Jonny On 12/02/2010 19:24, Victor Duchovni wrote: On Fri, Feb 12, 2010 at 05:14:30PM -, Jonathan Tripathy wrote: My current server has 256MB RAM (It's a VM on slicehost). How many users do you think that will handle? Is more RAM substantially more expensive? 256 MB is rather meek these days. With physical servers, one typically gets 16GB or more of RAM these days. Even a 6-Watt Atom-CPU FitPC box comes with 1GB of RAM! Your machine is way off the mainstream memory curve... For Postfix alone you're fine, but for running an IMAP server with users, you are likely too cramped, ask on the Dovecot list, not here. Postfix is not very memory intensive.
Re: Scalable
On Fri, Feb 12, 2010 at 05:17:26PM -0500, Aaron Wolfe wrote: If you want to give your client good advice, you will have to measure their mail flow in a meaningful way. How many messages per second, minute, hour, day do you need to handle? How many concurrent SMTP sessions? Do they even care if a message takes 100ms vs 100 seconds to traverse this system? No, this is largely irrelevant. What matters is the IMAP performance they expect, that IMAP servers are reasonably CPU and memory intensive. -- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note.
Re: Scalable
On Fri, Feb 12, 2010 at 06:24:59PM -0500, Aaron Wolfe wrote: If spam filtering is going to be used, it would be wise to consider those requirements as well. A host with 256MB of RAM is not going to be doing much heavy lifting with content inspection. -- Viktor. P.S. Morgan Stanley is looking for a New York City based, Senior Unix system/email administrator to architect and sustain our perimeter email environment. If you are interested, please drop me a note.
