I am practicing putting together a HA file server. It is a linux server with 2 1.5TB Hard drives. My plan is to use LVM to manage the physical volumes into logical volumes for /, /home, and /var. Then use md (soft RAID 1) to mirror the image onto the second HDD, THEN use DRDB to mirror the entire setup another server.

Is this overkill? Would I just be okay with just md and DRDB? The system will serve user's homedirs (~100) and probably some groupware or other local intranet. On my own machines I've always separated root and /home partitions in case I break something, I can easily reinstall the OS. Should I follow that same theory here? If so I need LVM, because I really can't predict where we'll need more space, /var or /home.

  • Remember: the more are technologies involved, the more chance is to see bug or failure in one of each stacked system... border effect and other funny/interesting things! Keep your backups up to date!!! – F. Hauri Jul 18 '13 at 6:24

It sounds like a good setup to me, except I would put the MD layer below the LVM layer. So instead of having LVM volumes that you then put MD on, put MD on your disks and then add the resulting RAID volume to your LVM volume group. This will give you some more robustness when the time comes to add or modify your LVM configuration.

I use pretty much the identical setup for some failover virtualization servers. If you throw in Pacemaker to the mix you get a fairly automated high-availability solution.

  • Great thanks for the tip-- but how do I do this install? Install the base system first on a normal ext3 partition, boot up. Then set up md and lvm to manage the rest of the space, mount those filesystems, copy /, /var, /home over accordingly, edit /etc/fstab, reboot? – mtkoan May 12 '10 at 12:15
  • Ok, I can do this before I install the base system. This more self-evident on Slackware, but I can just Alt-F1 to a shell to manage it in Debian too. I think I'm going to go with Debian even though I think Slack is better... – mtkoan May 12 '10 at 14:51
  • I'm pretty sure the Debian installer supports setting up an MD raid as the root disk. See dev.jerryweb.org/raid for a HOWTO. – Kamil Kisiel May 12 '10 at 18:42

Why would it be overkill? If you want to dynamically manage the volumes, LVM is the way to do it. RAID1 and DRDB are good high availability solutions.

I like to separate volumes that I need to manage with different mount options, partitions, and settings.

Another primary reason would be a volume that I expect to grow, as I would dedicate a separate disk set to it for an easier upgrade path.

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