"Karl E. Jorgensen" <k...@jorgensen.org.uk> writes: > Hi > > On Wed, Nov 12, 2014 at 10:09:43PM +0100, lee wrote: >> Hi, >> >> what's the best way to move existing logical volumes or a whole volume >> group to new disks? >> >> The target disks cannot be installed at the same time as the source >> disks. I will have to make some sort of copy over the network to >> another machine, remove the old disks, install the new disks and put the >> copy in place. > > Having to do this over the network makes it slightly > complicated.... But not impossible. > >> Using dd doesn't seem to be a good option because extend sizes in the >> old VG can be different from the extend sizes used in the new VG. >> >> The LVs contain VMs. The VMs can be shut down during the migration. >> It's not possible to make snapshots because the VG is full. > > Ok. > >> New disks will be 6x1TB RAID-5, old ones are 2x74GB RAID-1 on a >> ServeRaid 8k. No more than 6 discs can be installed at the same time. > > Assuming that: > > * both machines can be online at the same time > > * there is a good network connection between them. The fatter the pipe > the better > > * both run Debian. Obviously
One is running Fedora. I could install Debian on it if that helps. > * The VMs are happy to (eventually) migrate to the new hardware box The server remains the same, only the disks are being replaced. The SeverRaid 8k doesn't like the WD20EARS (and they are slow), so I'm replacing them. > Then there is a sneaky way, which can help minimize the downtime: LVM > and network block devices (or iSCSI. Either can work). Chunky, > slightly hacky, but worth considering. > > The basic idea is: > > * On the receiving machine, prepare the disks. Export the *whole* > disks (or rather: the RAID device(s)) using nbd, xnbd or iSCSI. I'd have to attach the disks to a SmartArry P800, and the ServeRaid 8k won't be able to read them. I'd have to use the 1TB spare disk instead to move the volumes to. Once they're moved over, I could replace the disks in the sending machine and move the LVs back the other way round. > * On the sending machine: attach the disks over the network, using nbd > client, xndb client or iSCSI. Hm, I need to learn about that ... Looking at things, aoe seems to be a good idea --- if that works with hardware RAID and SATA. > [...] > > Hope this helps Yes, thank you :) It's a very interesting idea. Fortunately, downtime isn't an issue. I also have a 32GB USB stick, and all the LVs are smaller than 32GB. Since there seems to be some agreement that it would be best to use pvmove, I think I could, one after the other, move all the LVs to the USB stick with pvmove, plug the USB stick into the other machine, move the LVs onto a hard disk in the other machine, replace disks and move the LVs back the same way. I can keep the VMs shut down while doing this, which allows me to just move the USB stick rather than moving over the network. However, over the network might be more reliable, and I could move all VMs at once with minimal downtime. Hmmm ... -- Again we must be afraid of speaking of daemons for fear that daemons might swallow us. Finally, this fear has become reasonable. -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/871tp6ri79....@yun.yagibdah.de
