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.
Re: Scalable
Jonathan Tripathy put forth on 2/12/2010 5:05 PM: > Hi Stan, Hi. Try to keep the discussions on list so everyone can assist. > You've hit a very good question. They don't currently have an office > email system. Staff are using their personal Hotmail accounts when they > need to send the odd email. Do you see why I orignally was going to get > a 256MB RAM VM to allow them to have 50 or so email accounts? No, I can't. I can understand your thought process, but it's wrong. Leaving a really bad situation for another one that's not quite as bad is not the same as going to a good situation. Architect a solution that fits the client's needs, not a solution that's just a little better than what they have, but overall still doesn't come close to meeting their needs. > Just some other company has come in saying that they'll do 600, and even > though my price is much cheaper, it's now being seen as "too cheap"... Bid the job right. Write up a proposal explaining what they need, why they need it, and how much it's going to cost. > I was thinking this server: > > http://www.fasthosts.co.uk/dedicatedservers/linux-servers/ds300-linux/ You're still not looking at this from the proper perspective. You're looking at ISP rented colo offerings and trying to match one you think might fit the client's need. This is called an "ass backwards" approach to system design. Identify the client's needs, then architect the system, then pick the hardware, vendors and providers that best fit that need. You didn't mention what their broadband connection speed is. We need to know that to help you properly architect this thing. The lower that bandwidth, the greater the need to have the mail server on site and not in a colo. To be completely honest, from what I've seen from you to this point, it sounds like everyone in this scenario might be better off just using Google apps. Charge a decent "conversion" fee, add in some training, and once they're up and running you don't have to "manage the box", which it seems you're not really up to anyway. -- Stan
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.
Re: Scalable
On Fri, Feb 12, 2010 at 5:41 PM, Victor Duchovni wrote: > 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. > I was speaking about Postfix. Of course other software will have its own requirements. If spam filtering is going to be used, it would be wise to consider those requirements as well. On my largest server we do not use any IMAP software, but we do use spamassassin. SA uses considerably more resources than Postfix per SMTP process. > -- > 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
Jonathan Tripathy put forth on 2/12/2010 3:50 PM: > 2.8 Dual Core > 2GB RAM What about disk? Disk is typically the key subsystem for mail performance. Fast CPUs don't do much for mail without a fast disk subsystem. At minimum get hardware mirroring for two disks (RAID 1) and best to make them 10K or 15K rpm models. 7.2K rpm disks might not cut it for 600 users unless you go hardware RAID 10 with 4 disks. > how much would that handle? With the right disk subsystem, those specs above with Postfix + Dovecot IMAP + antispam stuff + etc should be plenty. > 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.. What is the up/down link speed of the broadband connection? If's it's something like the low ball minimum 1.5M/512K the speed of the server won't mean much, just as you surmise. And if that is the case, this smtp/imap server should be placed on site at the business location, not in a colo. Where is their current mail server located? Also, you need to get some usage data from their current server to find out exactly what their flow volume is. -- Stan
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 4:50 PM, Jonathan Tripathy 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
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 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
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 12:14 PM, Jonathan Tripathy 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 > >
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
