I''m building a new qmail based mail server. I now have a quad-core server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a virtual web server on that host too, so I''m installing Xen on that host. What I am wondering now is should I install qmail also on a virtual server (domU) or on the master server (dom0)? Has anyone experience about running qmail under xen domU? I could dedicate 1-2 cores for the qmailtoaster domU and lots of RAM, but I''m a bit worried about disk I/O, as I''ve read that this can be a bottleneck in Xen. I''d like to hear stories like "I''ve run mail server on a domU with 100 active domains and 10 000 incoming messages a day without problems)" :) Cheers, Peter _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 05/07/2008 17:25, Peter Peltonen wrote:> I''m building a new qmail based mail server. I now have a quad-core > server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a > virtual web server on that host too, so I''m installing Xen on that > host. What I am wondering now is should I install qmail also on a > virtual server (domU) or on the master server (dom0)?I''d say in it''s own domU, given you''ve installed xen, incidentally (not a trick question!) why did you pick xen for the web server?> Has anyone > experience about running qmail under xen domU? I could dedicate 1-2 > cores for the qmailtoaster domU and lots of RAM, but I''m a bit worried > about disk I/O, as I''ve read that this can be a bottleneck in Xen.my dom0 hardware can sustain over 320MB/s, a linux domU on that box gets 140MB/s and a windows domU up to 50MB/s> I''d > like to hear stories like "I''ve run mail server on a domU with 100 > active domains and 10 000 incoming messages a day without problems)" > :)Can''t say I have, but that doesn''t sound *so* challenging, I''m sure my laptop gets half that amount of spam a day ;-) I do run a postgres/dovecot/squirrelmail server on a domU with about 20 domains, volumes are lower, but I don''t think it''d worry me if they went up ten fold ... _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Sat, 2008-07-05 at 19:25 +0300, Peter Peltonen wrote:> I''m building a new qmail based mail server. I now have a quad-core > server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a > virtual web server on that host too, so I''m installing Xen on that > host. What I am wondering now is should I install qmail also on a > virtual server (domU) or on the master server (dom0)? Has anyone > experience about running qmail under xen domU? I could dedicate 1-2 > cores for the qmailtoaster domU and lots of RAM, but I''m a bit worried > about disk I/O, as I''ve read that this can be a bottleneck in Xen. I''d > like to hear stories like "I''ve run mail server on a domU with 100 > active domains and 10 000 incoming messages a day without problems)" > :)Try when possible to never, ever run a service on dom-0 that needs to allocate memory based on what the world feeds or demands of it (i.e. qmail, apache, etc). SSH is bad enough given the popularity of random forky brute force attacks. To put you at ease : I run approximately 20 such dom-u''s , with 300 virtual hosts each using Exim, no issues. Cheers, --Tim -- Monkey + Typewriter = Echoreply ( http://echoreply.us ) _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Peter Peltonen wrote:> I''m building a new qmail based mail server. I now have a quad-core >*WHY*??? Qmail has many cool technical features, but it''s licensing has been extremely burdensome, as has its packaging. Mr. Bernstein has relented and placed his work in the public domain, but it languished for years for that reason. Debugging it in any environment without your own sophisticated sys-geek to work around Mr. Bernstein''s policies is.... awkward.> server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a > virtual web server on that host too, so I''m installing Xen on that > host. What I am wondering now is should I install qmail also on a > virtual server (domU) or on the master server (dom0)? Has anyone > experience about running qmail under xen domU? I could dedicate 1-2 > cores for the qmailtoaster domU and lots of RAM, but I''m a bit worried > about disk I/O, as I''ve read that this can be a bottleneck in Xen. I''d > like to hear stories like "I''ve run mail server on a domU with 100 > active domains and 10 000 incoming messages a day without problems)" > :) >Why not use Dovecot? It''s built into contemporary Fedora and CentOS, which themselves are well integrated with Xen and perform reasonably well in paravirtualization. And you can use MRTG and tools like it to monitor your disk I/O now, to get some sort of standard to compare against. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Nico Kadel-Garcia wrote:> Peter Peltonen wrote: >> I''m building a new qmail based mail server. I now have a quad-core >> > *WHY*??? Qmail has many cool technical features, but it''s licensing > has been extremely burdensome, as has its packaging. Mr. Bernstein has > relented and placed his work in the public domain, but it languished > for years for that reason. Debugging it in any environment without > your own sophisticated sys-geek to work around Mr. Bernstein''s > policies is.... awkward.I agree completely with this -- qmail is a pain and there are good reasons why it''s not in the major distros.> >> server with 8 gigabytes of RAM and RAID-5 disk setup. I need to run a >> virtual web server on that host too, so I''m installing Xen on that >> host. What I am wondering now is should I install qmail also on a >> virtual server (domU) or on the master server (dom0)? Has anyone >> experience about running qmail under xen domU? I could dedicate 1-2 >> cores for the qmailtoaster domU and lots of RAM, but I''m a bit worried >> about disk I/O, as I''ve read that this can be a bottleneck in Xen. I''d >> like to hear stories like "I''ve run mail server on a domU with 100 >> active domains and 10 000 incoming messages a day without problems)" >> :) >> > Why not use Dovecot? It''s built into contemporary Fedora and CentOS, > which themselves are well integrated with Xen and perform reasonably > well in paravirtualization. > > And you can use MRTG and tools like it to monitor your disk I/O now, > to get some sort of standard to compare against.RAID5 isn''t going to be good for mail: a lot of the disk-writes are going to be very small and there are going to be a hell of a lot of them, especially with that kind of incoming load. Actually, with that kind of incoming load I don''t think you''re going to want to run the mail server on anything other than the bare metal anyway: virtual machines work well when you have servers that are individually relatively lightly loaded and it doesn''t look as though yours is. jch _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 07/07/2008 16:38, G. Michael Carter wrote:> 320MB/s? What are you running?8x SATA II 750GB disks on a PCI-X controller (with mdraid RAID5) http://www.supermicro.com/products/accessories/addon/DAC-SATA-MV8.cfm> Most I get is 60MB/s (that was even without xen)Sounds like a single spindle? _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi all and thanks for your replies, On Mon, Jul 7, 2008 at 7:36 PM, Nico Kadel-Garcia <nkadel@gmail.com> wrote:> Peter Peltonen wrote: >> >> I''m building a new qmail based mail server. I now have a quad-core >> > > *WHY*??? Qmail has many cool technical features, but it''s licensing has been > extremely burdensome, as has its packaging. Mr. Bernstein has relented and > placed his work in the public domain, but it languished for years for that > reason. Debugging it in any environment without your own sophisticated > sys-geek to work around Mr. Bernstein''s policies is.... awkward.Because qmail works well for me (it''s been very reliable) and I know how to administrate it. And there are nice communities around that provide tools/SRPMs for installing/upgrading it easily, for example http://www.qmailtoaster.com Regards, Peter _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Hi, On Tue, Jul 8, 2008 at 2:58 PM, John Haxby <john.haxby@oracle.com> wrote:> RAID5 isn''t going to be good for mail: a lot of the disk-writes are going to > be very small and there are going to be a hell of a lot of them, especially > with that kind of incoming load. Actually, with that kind of incoming load > I don''t think you''re going to want to run the mail server on anything other > than the bare metal anyway: virtual machines work well when you have servers > that are individually relatively lightly loaded and it doesn''t look as > though yours is.Are you speaking from experience or is this just a well educated guess? Are many small disk writes something that Xen is particullary not good with? Best, Peter _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
John Haxby wrote:> RAID5 isn''t going to be good for mail: a lot of the disk-writes are > going to be very small and there are going to be a hell of a lot of > them, especially with that kind of incoming load. Actually, with that > kind of incoming load I don''t think you''re going to want to run the mail > server on anything other than the bare metal anyway: virtual machines > work well when you have servers that are individually relatively lightly > loaded and it doesn''t look as though yours is.While I agree RAID5 isn''t the best choice, the choice to virtualize is sound. 10K emails a day is nothing. 10,000K emails an hour is a different story, but if you start virtualizing your mail servers now you can keep adding mail servers to accommodate increasing load without having to build out spectacularly big data centers, and be able to add redundancy and spread load evenly. RAID10 is the way to go for just about everything except streaming media and generic flat file servers. -Ross ______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On 11/07/2008 17:54, Peter Peltonen wrote:> Are many small disk writes something that Xen is particullary not good with?It''s something RAID5 is bad at. _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Peter Peltonen wrote:> Hi all and thanks for your replies, > > On Mon, Jul 7, 2008 at 7:36 PM, Nico Kadel-Garcia <nkadel@gmail.com> wrote: >> Peter Peltonen wrote: >>> I''m building a new qmail based mail server. I now have a quad-core >>> >> *WHY*??? Qmail has many cool technical features, but it''s licensing has been >> extremely burdensome, as has its packaging. Mr. Bernstein has relented and >> placed his work in the public domain, but it languished for years for that >> reason. Debugging it in any environment without your own sophisticated >> sys-geek to work around Mr. Bernstein''s policies is.... awkward. > > Because qmail works well for me (it''s been very reliable) and I know > how to administrate it. And there are nice communities around that > provide tools/SRPMs for installing/upgrading it easily, for example > http://www.qmailtoaster.comJust be sure that you keep track of all of the 3rd party patches that you have to apply to qmail to turn it into a modern MTA. You may also want to do your own regression testing of these patches against one another because its unlikely that anyone else has done such regression testing. Dan has, IIRC, made the licensing less restrictive but that doesn''t change the fact that the model that qmail operates on by default is not terribly modern. Eg; ''all mail must be either delivered or bounced'' does not work any more. Sad but true. When I started work in my current job we had a qmail server. At first I thought that it was a perfectly good MTA. I changed my opinion very sharply after working with it for a few months. After attempting to upgrade it and discovering that it had several 3rd party patches applied and that noone knew exactly *what* had been applied it was pretty well unmaintainable. Now using exim... _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users