On Mon, Jun 10, 2019 at 11:22 PM David Teigland <[email protected]> wrote:
> On Mon, Jun 10, 2019 at 10:59:43PM +0300, Nir Soffer wrote: > > > [root@uk1-ion-ovm-18 pvscan > > > /dev/mapper/36000d310056978000000000000000014: Checksum error at > offset > > > 4397954425856 > > > Couldn't read volume group metadata from > > > /dev/mapper/36000d310056978000000000000000014. > > > Metadata location on /dev/mapper/36000d310056978000000000000000014 at > > > 4397954425856 has invalid summary for VG. > > > Failed to read metadata summary from > > > /dev/mapper/36000d310056978000000000000000014 > > > Failed to scan VG from /dev/mapper/36000d310056978000000000000000014 > > > > This looks like corrupted vg metadata. > > Yes, the second metadata area, at the end of the device is corrupted; the > first metadata area is probably ok. That version of lvm is not able to > continue by just using the one good copy. Can we copy the first metadata area into the second metadata area? Last week I pushed out major changes to LVM upstream to be able to handle > and repair most of these cases. So, one option is to build lvm from the > upstream master branch, and check if that can read and repair this > metadata. > This sound pretty risky for production. > David, we keep 2 metadata copies on the first PV. Can we use one of the > > copies on the PV to restore the metadata to the least good state? > > pvcreate with --restorefile and --uuid, and with the right backup metadata > What would be the right backup metadata? > could probably correct things, but experiment with some temporary PVs > first. > Aminur, can you copy and compress the metadata areas, and shared them somewhere? To copy the first metadata area, use: dd if=/dev/mapper/360014058ccaab4857eb40f393aaf0351 of=md1 bs=128M count=1 skip=4096 iflag=skip_bytes To copy the second metadata area, you need to know the size of the PV. On my setup with 100G PV, I have 800 extents (128M each), and this works: dd if=/dev/mapper/360014058ccaab4857eb40f393aaf0351 of=md2 bs=128M count=1 skip=799 gzip md1 md2 Nir
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