[linux-lvm] Hot backup for boot/root disk

[Toby Bluhm]

Hacksaw wrote:
> I have a Linux system with 2 identical disks for the OS portion. The 
> goal is to have them essentially mirrored, but not continuously. I want 
> to be able to rsync them on occasion.
> 
> I need this disk to be bootable on a moments notice, in case the main 
> one dies.
> 
> The layout of the current boot disk is a partition for /boot which is 
> ext3, and then the rest as a LVM set, of essentially one large partition.
> 
> My first thought is to create the second disk pretty much as the first 
> was created, do the rsyncs, and make some script that will maintain the 
> configuration files which mention the physical disks.
> 
> I have to admit that it's unclear what they all are.
> 
> In fact, I'd prefer something clever with disk labels.
> 
> In the best of all possible worlds, the system would recognize the 
> bootable partitions, and fail over to the backup one if there was a 
> problem with the main one.
> 
> I would appreciate some advice here. I need this machine to go live in a 
> few days, as the server it's replacing is close to just falling over 
> after more than 6 years of active service, all honor to it.
> 

Some people like using LVM for system/OS disks - I don't. So I would
ditch the LVM and use software raid1. I don't understand why you
wouldn't want the disks to be constantly in sync. What if they're out of
sync when a disk dies? However, you could break and rebuild the mirror
at your whim when using sw raid.


--Toby