On Wed, Apr 18, 2012 at 04:55:01PM +1000, Russell Coker wrote:
Sorry, my previous message wasn't clear.
I will use ZFS for the main data storage but Ext3 for booting in a separate mdadm device.
OK, you mean having a small partition on each disk in the zpool, with mdadm raid-1 for the rootfs? sure, that'll work. mdadm has no problem with multiple extra devices in a RAID-1. and reads should be amazingly fast. however, zfs works much better if you give it entire disks rather than partitions. in particular, it can disable write barriers and get much better performance. IIRC it can't do that with partitions because it doesn't know what else may be writing to the disk. making zpools from partitions does work, but is very strongly discouraged.
Booting from ZFS sounds like too much effort for no real benefit.
for an existing system, yeah. for a new one, probably not that much hassle. one method that should work might be: do the initial install on a spare disk (because only debian's kfreebsd supports installation on zfs right now), reboot, create your zpool(s), rsync rootfs to zfs, chroot, reconfigure and re-install grub, make sure that zfs-initramfs package is installed and run update-initramfs. rebooting again without the spare disk should give you a working root on zfs. if it doesn't work first time, plug the spare disk back and fix :) craig -- craig sanders <cas@taz.net.au> BOFH excuse #63: not properly grounded, please bury computer