I had a power issue in the house recently, and had issue getting my file server disks to mount. Turns out that one of the devices had renamed itself from sdb to sdd, and all of the LVM metadata is now missing. Using pvscan, lvscan, vgscan, etc all only show my system partition. Another reboot and the devices seemed to go back to they were before: sdb and sdc. I've managed to reassemble the raid using mdadm, but was unable to use vgcfgrestore to recreate my lvm configuration because apparently the UUID of my raid device has changed. My original VG was named vg0. Here's the result of vgcfgrestore:  Couldn't find device with uuid 3fgedF-F7Dc-c300-svuP-b3Q3-qSnb-CukkLq.  Cannot restore Volume Group vg0 with 1 PVs marked as missing.  Restore failed.My /etc/lvm/backup/vg0 file shows this:vg0 {    id = 3JWsYl-FmEP-gpsa-7grO-VlLU-x7uC-EevgFc    seqno = 3    format = lvm2         # informational    status = [RESIZEABLE, READ, WRITE]    flags = []    extent_size = 8192      # 4 Megabytes    max_lv = 0    max_pv = 0    metadata_copies = 0    physical_volumes {        pv0 {            id = 3fgedF-F7Dc-c300-svuP-b3Q3-qSnb-CukkLq            device = /dev/md0 # Hint only            status = [ALLOCATABLE]            flags = []            dev_size = 3907028992   # 1.81935 Terabytes            pe_start = 384            pe_count = 476932   # 1.81935 Terabytes        }    }    logical_volumes {        data {            id = Sqjebo-rnKh-mgQH-a90E-Q0n7-idp1-1xPP56            status = [READ, WRITE, VISIBLE]            flags = []            segment_count = 1            segment1 {                start_extent = 0                extent_count = 476932   # 1.81935 Terabytes                type = striped                stripe_count = 1    # linear                stripes = [                    pv0, 0                ]            }        }    }}So the issue it seems I'm having is that the pv UUID is no longer valid, and I'm not even sure now what to use. The raid I managed to reassemble with --scan auto-named to /dev/md1, but even changing that in the vg0 backup file had no effect. I'm still not sure what the new pv UUID is. # cat /proc/mdstatPersonalities : [raid1] md1 : active raid1 sdc1[1] sdb1[0]      1953383488 blocks super 1.2 [2/2] [UU]      bitmap: 0/15 pages [0KB], 65536KB chunkunused devices: <none>Again, pvs, lvs, and vgs all show only my root/system volumes and vg's, nothing from vg0. Any suggestions on next steps? Both drives are full of data (most of which is backed up) but I'd like to take whatever steps I can to save the filesystems.EDIT: Displaying the head of both disks (/dev/md1 shows garbage). I notice that only one of them has a LABELONE label:[root@host ~]# head /dev/sdb1N+y{GyRjedi:1RUY1iSnZsH$WYuQ>4vg0 {id = IwXCM3-LnxU-Oguo-PXiN-nXwq-VFaU-ZmgySsseqno = 1format = lvm2status = [RESIZEABLE, READ, WRITE]flags = []extent_size = 8192max_lv = 0max_pv = 0metadata_copies = 0[root@host ~]# head /dev/sdc1LABELONEpu+ LVM2 0013fgedFF7Dcc300svuPb3Q3qSnbCukkLqN+y{GyRjedi:1RUYPFlO!H$WYuQ9vg0 {id = IwXCM3-LnxU-Oguo-PXiN-nXwq-VFaU-ZmgySsseqno = 1format = lvm2status = [RESIZEABLE, READ, WRITE]flags = []extent_size = 8192max_lv = 0max_pv = 0metadata_copies = 0So now the 50 cent question: how do I recover the LVM labels without damaging the underlying filesystem?UPDATE:So I was basically able to successfully execute vgcfgrestore to a valid copy of my lvm backup config using a new PV UUID, and assembled /dev/md0 with that one drive, but now I'm getting a message that my PV is smaller than the allocated space. Basically it's reporting that my physical extents dropped from 476932 to 476900. The size of the disk hasn't changed, and I verified that the PV actually does have the correct number of extents available: (see the last line)[root@host /]# pvs -v --segments /dev/md0    Using physical volume(s) on command line.    Wiping cache of LVM-capable devices    Wiping internal VG cache  Device /dev/md0 has size of 3906766976 sectors which is smaller than corresponding PV size of 3907028992 sectors. Was device resized?  One or more devices used as PVs in VG vg0 have changed sizes.  PV         VG   Fmt  Attr PSize PFree Start SSize  LV   Start Type   PE Ranges  /dev/md0   vg0  lvm2 a--u 1.82t    0      0 476932 data     0 linear /dev/md0:0-476931The last line shows that it's reporting extents from 0-476931, which is the correct size. I thought perhaps that the LVM headers itself may consume some space, but this isn't a new volume, it's been used for years without any issue and has never been resized.  The volume is showing as suspended:  LV Status              suspended  # open                 0I attempted to extend my PV with a USB thumbdrive (didn't think it would work, and it didn't) thinking if I could even temporarily mount this filesystem I could copy off the data and then create the whole raid from scratch, but of course that was not effective. Any thoughts on possible next steps to save the data?
LVM metadata missing, trying to recreate raid 1 with LVM
raid;lvm;software raid;mdadm;raid1