[mythtv-users] MythTV updates, back out plan, lvm snapshots

[Raymond Wagner]

On 2/26/2012 08:05, Brent Bolin wrote:
> Assuming core OS is all in a single lv.

Depending on how you configure your system, that's not all that 
difficult.  The setup I've been running for over three years now is 
several similar frontends booting off iSCSI images on a FreeBSD/ZFS 
target.  I have a base image that I periodically mount on one of the 
frontends and update.  All of the frontends get shut down, a new base 
image is cloned for each frontend, and they all boot into their own 
individual copy.  A simple init script in the base image has each 
frontend rsync an overlay of configs and states from the server and 
reboot.  The whole process takes maybe 4 minutes.

Since the images are stored on ZFS, which is a COW filesystem, the 
clones are basically free.  Each update on the frontend might carry a 
couple hundred MB for the theme cache, plus another couple hundred for 
the updated packages on the base image.  While I require a custom initrd 
to mount the iSCSI image, Linux thinks it's a real disk, so I don't need 
any of the funky NFSboot modifications to init.  Each frontend has a 
dedicated image, so there is no fiddling about with read only 
filesystems, or stacked NFS shared and union filesystems.  I can boot 
into any of several previous images for each frontend through the 
PXELinux configs.