I'm not on the list. Please always keep me in the CC. On Fri, Nov 07, 2008 at 02:46:24PM -0600, Boyd Stephen Smith Jr. wrote: > On Friday 07 November 2008, William Thompson <[EMAIL PROTECTED]> > wrote about 'Re: device mapper help': > >On Fri, Nov 07, 2008 at 11:44:00PM +0800, hhding.gnu wrote: > >> William Thompson wrote: > >> > > >> > Is there a tool somewhere that will allow me to merge a snapshot into > >> > the parent device? > >> > >> As far as I know, LVM does not provide this function. ZFS can promote > >> it's snapshoot. > > > >I'm not using LVM for this functionality. I want this on the block > > level, not the fs level. > > What are you using to take snapshots, then? Also, LVM doesn't know > anything about filesystems -- it does everything "on the block level".
dmsetup manually. > Also, you certainly don't want to update a block device's data while > there's a mounted filesystem on top of it, so the filesystem (and any > other layers between in device and the fs) are definitely of concern. I knew this. But this isn't what I was referring to. Let me try to explain it in a different way (more to what I'm really doing, the config I gave before was an example of what I wanted) I'm doing something like this: # dmsetup create disk-0 0 16777216 zero # lvcreate -l 1024 -n disk-1-cow vg0 # dmsetup create disk-1 0 16777216 snapshot /dev/mapper/disk-0 /dev/vg0/disk-1-cow P 8 # dmsetup create disk 0 16777216 linear /dev/mapper/disk-1 0 # <do something with /dev/mapper/disk, like a VM> <stop using /dev/mapper/disk> # lvreduce -l <smallest size possible> vg0/disk-1-cow # dmsetup table disk-1 | dmsetup -r reload disk-1 # dmsetup resume disk-1 # lvcreate -l 1024 -n disk-2-cow vg0 # dmsetup create disk-2 0 16777216 snapshot /dev/mapper/disk-1 /dev/vg0/disk2-cow P 8 # dmsetup reload disk 0 16777216 linear /dev/mapper/disk-2 0 # dmsetup resume disk # <do some more stuff> At this point, maybe I don't want the disk-1 snapshot anymore but want to merge in the changes from disk-2 so that disk-1 is now disk-1 + disk-2 and remove or invalidate disk-2. I'm looking for a took that can take /dev/vg0/disk-2-cow and update the modified sectors in /dev/mapper/disk-1. I have already figured out that I've had some problems with the above if I don't do it right (In this case it was under kvm-qemu when I didn't want to keep the last snapshot). -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
