>>>>> "Tony" == Tony Arnold <tony.arnold@manchester.ac.uk> writes: Tony> John, Tony> On 24/11/15 16:49, John Stoffel wrote: >> Can I make a suggestion to you? Instead of trying to do the mirroring >> in LVM, build yourself an MD mirror, then layer LVM ontop of that >> instead. You get nice seperation. >> >> You can also take that /dev/sdb3, make it into an MD RAID1 array with >> just one device, add it into the VG, then move the LVs onto the new >> device. Once that's done, you remove the sda3 from the VG, then add >> it into the MD device. Something like this... >> >>> mdadm --create /dev/md1 --level=1 --raid-devices=2 /dev/sdb3 missing >>> cat /proc/mdstat >>> pvcreate -v /dev/md1 >>> vgextend -v vg0 /dev/md1 >>> pvmove -v sda3 >>> vgreduce -v vg0 sda3 >>> mdadm --add /dev/md0 /dev/sda3 >>> cat /proc/mdstat >> >> And you will now be mirrored, etc. Tony> Thanks for your suggestion which I have now implemented. The pvmove took Tony> a few hours (1.5TB to move!) and then also some more hours while the Tony> mirror set synchronised. But it's all done and I now have my volumes Tony> mirrored. Tony> I'm still curious though why the LVM based RAID1 didn't work. I'll just Tony> have to stay curious! I suspect it could have been made to work, but in my experience, there's a very active MD developer (Neil, who would love more help!) who does a great job of the pure RAID features that MD provides. The DM guys are more based on logical block management in my experience, and so don't do nearly as much in the RAID side of things. But in any case, the above setup works really well, and gives you a good seperation of the layers and is easy to manage and control. I'm planning on migrating all my setup to a lvm-cache setup, with a pair of 4TB disk mirrored (and possibly a third mirror of two striped 2Tb drives... belt and suspenders!) with a pair of MX200 SSDS, 500Gb for boot and cache duties. Should be a nice fast setup, and take less power as well. John _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
