Linux - ServerThis forum is for the discussion of Linux Software used in a server related context.
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
IMOHO: What you really want is either SAN shared storage, or a cluster file system.
I love DRBD but have found it unreliable during maintenance events. An upgrade that you would not think pertaining can break it easily. If you use it you need a duplicate environment where you can test every patch and upgrade. (needed in my enterprise environment anyway, but overkill and wasteful for any smaller office)
This is very much a subjective question, and is dependent entirely on your environment. If money is available for it, I agree that a LUN (on a well-performing SAN) would be ideal. For an active-passive cluster, you wouldn't necessarily even need a clustered filesystem. For active-active, of course, you would.
I have no experience with DRBD yet, but listen carefully to wpeckham's comments. If you're going to deploy DRBD for a critical application, then be sure you have a proper test environment and procedures for vetting all system updates before doing them in production.
You probably do not want rsync(1) as a solution, unless 1) your mail server is low volume; and 2) you can accept some level of lost messages. That is an entirely different category than block-level storage (SAN LUN) or block-level replication (DRBD), BTW, so your dichotomy of "rsync vs. DRBD" probably needs more analysis and thought.
thank you guys for your guides,
i want to run failover with DRBD+pacemaker (debian Lenny) but after two weeks i haven't succeed yet, i dont know if i continue or stop it and use rsync+pacemaker..
my mail server is very important and i dont want see it's failur..
Rsync is one of my goto tools. Nice fast secure. It is NOT, however, any kind of realtime solution.
I have made the combination of OpenVZ, heartbeat, and DRBD work for a high availability server, but it was tricky, fragile, and complex. There are purposes I might recommend it for, but mail is not one.
A cluster or distributed (shared) file system is perfect for what you want to do. the replication is real-time and no storage failover is required only assumption of the mail server network address. While a cluster would allow you to use two or three server and do load-share as well as instant failover, it might be overly complex for your needs. The shared filesystem and intelligent failover are the only parts you need to make this elegant.
A few years ago this would have been difficult, today there are several filesystems to choose from and dozens of how-to documents on the web. Look up some of the clusters or distributed file systems, pick a couple of the newer, and google for documents related.