I have been running an email system for an academic department for ages that consists of postfix, procmail, dovecot, clamav, spamassassin, MailScanner, ldap, maildir, xfs, lvm, CentOS. Number of users are around 3000 and hardware supply is not an issue. Currently running the exact setup on two separate servers , kind of sharing the load. I have been, lately, considering virtualizing the whole setup. Any reason why NOT to virtualize? thanks.
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Virtualisation may be quickest way to balance your risk (although not your load). Strongly recommend that you don't consider Physical to Virtual (p2v) conversion if you do virtualise.– dunxdMar 13, 2012 at 11:57
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Thank you everyone that replied. As we are a small cluster of systems (around 35 servers running a small service provider actually) virtualizating email is not the only virtualization being done. The obvious reasons for virtualization apply ie consolidation, "balance risk", power consumption etc. From what has been said below I take it I will virtualize the Email infrastructure also. Your opinions actually re-enforced my view of things. Thanks.– ankMar 15, 2012 at 7:44
5 Answers
It is nice to virtualize to get a failover when one machine fails. You can have a shadow of one machine that automatically takes over if another machine fails. I will also be easier to add storage should you run out of initial disk space. It will also be better for you availability and scaling. So in my opinion, there is no reason not to virtualize.
Large chunks of an email system are easy to visualize. You'd be better and safer to stay separating out the system and visualizing the bits that come apart.
For example, all the AV and spam systems are easy to drop onto another host without affecting anything. Same with the database in the backend. If you progress it far enough, you'll end up with only the physical hardware doing the storage of the email leaving most of the ram for caching purposes there. If your storage is NFS based (which I doubt due to the mention of xfs/lvm) then there would be no need to keep the physical hosts once the delivery/maildir VMs have enough ram to properly cache things.
Any reason why to virtualize? If you do it because it's a hot topic and everyone and his mother is talking about it , you don't do yourself a favor.
If you have an actual problem you need to solve or a strategy for the future where virtualization can be part of the solution, go for it. But don't do it just to say "I am going virtual".
Is there any reason why you want to change your current setup and virtualize things? If you need to do it for the feature (see SwenW's post), then do it. If you need to save money and would like to consume less energ, do it. But if your setup is fine the way it is now and you don't need to save money, then do not change the running system.
The basic intention of visualization is server consolidation. So if you have a server lying around with only marginal usage then yes you can virtualize it and put the server to good use by loading more virtual machines in it. Or else I don't see any sense in doing it.