Hello list,

I analyze this issue for some days. It looks a new bug.

trigger steps:
user execute pvresize to enlarge the pv.
After the command execution, one disk lvm metadata was overwrite by another 
disk lvm metadata.

once log (execute pvresize cmd), there are 7 disk occur read/write failed:
scsi-360060e80072a660000302a660000f748 (has fc68 metadata)
the f748 metadata was overwritten by fc68.

the fc67 fc66 f74c f74a f749 f748 error log are same:
#toollib.c:4377          Processing PVs in VG vgpocdbcdb1_r1
#locking/locking.c:331           Dropping cache for vgpocdbcdb1_r1.
#misc/lvm-flock.c:202         Locking /run/lvm/lock/V_vgpocdbcdb1_r1 WB
#misc/lvm-flock.c:100           _do_flock /run/lvm/lock/V_vgpocdbcdb1_r1:aux WB
#misc/lvm-flock.c:100           _do_flock /run/lvm/lock/V_vgpocdbcdb1_r1 WB
#misc/lvm-flock.c:47            _undo_flock /run/lvm/lock/V_vgpocdbcdb1_r1:aux
#metadata/metadata.c:3778        Reading VG vgpocdbcdb1_r1 tTwjvG-xxxx-FA0cJj
#metadata/metadata.c:3874          Rescanning devices for vgpocdbcdb1_r1
#cache/lvmcache.c:751           lvmcache has no info for vgname 
"vgpocdbcdb1_r1" with VGID tTwjvGfl1zsU6gODANVsela1siFA0cJj.
#label/label.c:629           Scanning 1 devices for VG info
#label/label.c:665           Scanning submitted 1 reads
#label/label.c:674           Scan failed to read 
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc67 error 0.
#device/bcache.c:189     WRITE last fd 36 last_offset 4608 last_sector_size 512
#device/bcache.c:244           Limit write at 0 len 131072 to len 4608
#label/label.c:764           Scanned devices: read errors 1 process errors 0 
failed 1
#cache/lvmcache.c:751           lvmcache has no info for vgname 
"vgpocdbcdb1_r1" with VGID tTwjvGfl1zsU6gODANVsela1siFA0cJj.
#cache/lvmcache.c:1410    VG info not found after rescan of vgpocdbcdb1_r1
#cache/lvmcache.c:751           lvmcache has no info for vgname 
"vgpocdbcdb1_r1" with VGID tTwjvGfl1zsU6gODANVsela1siFA0cJj.
#metadata/metadata.c:3884          Cache did not find fmt for vgname 
#metadata/metadata.c:3885          <backtrace>
#metadata/metadata.c:4518          <backtrace>

the fc68 error log is in below <1> subsection.

 From all the log files, user's disk have 3 classes issues:

1> disk (fc68) has old lvm extension header.

It will trigger lvm write action to update PV header (metadata area).

related log:
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc68: PV header extension 
version 1 found
... ...
#metadata/metadata.c:2842          PV 
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc68 has old extension 
header, updating to newest version.

In user machine, this write action was failed, the PV header data (first 4K) 
save in bcache (cache->errored list), and then write (by bcache_flush) to 
another disk (f748).

related error log:
#format_text/format-text.c:1470          Creating metadata area on 
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc68 at sector 8 size 2040 
#device/bcache.c:189     WRITE last fd 36 last_offset 4608 last_sector_size 512
#device/bcache.c:244           Limit write at 0 len 131072 to len 4608
#label/label.c:1333    Error writing device 
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc68 at 4096 length 512.
#format_text/format-text.c:407     Failed to write mda header to 
/dev/disk/by-id/scsi-360060e80072a670000302a670000fc68 fd -1

related code:
        +-> pv_needs_rewrite is 1
        |    set vg->pv_write_list
        +-> vg_write
  pv_write //vg->pv_write_list is not empty.
     lvmcache_foreach_mda(info, _write_single_mda, &baton)

static int  _raw_write_mda_header ()
     ... ...
     dev_set_last_byte(dev, start_byte + MDA_HEADER_SIZE);

     if (!dev_write_bytes(dev, start_byte, MDA_HEADER_SIZE, mdah)) {
         dev_unset_last_byte(dev); //zhm: useless, fd = -1 now!!
         return 0;

     return 1;

If dev_write_bytes failed, the bcache never clean last_byte. and the fd is 
closed at same time, but cache->errored still have errored fd's data. later lvm 
open new disk, the fd may reuse the old-errored fd number, error data will be 
written when later lvm call bcache_flush.

2> duplicated pv header.
    as <1> description, fc68 metadata was overwritten to f748.
    this cause by lvm bug (I said in <1>).

3> device not correct
    I don't know why the disk scsi-360060e80072a670000302a670000fc68 has below 
wrong metadata:

(please also read the comments in below metadata area.)
     vgpocdbcdb1_r2 {
         id = "PWd17E-xxx-oANHbq"
         seqno = 20
         format = "lvm2"
         status = ["RESIZEABLE", "READ", "WRITE"]
         flags = []
         extent_size = 65536
         max_lv = 0
         max_pv = 0
         metadata_copies = 0
         physical_volumes {
             pv0 {
                 id = "3KTOW5-xxxx-8g0Rf2"
                 device = 
                          I don't know why there is f768, please ask customer
                 status = ["ALLOCATABLE"]
                 flags = []
                 dev_size = 860160
                 pe_start = 2048
                 pe_count = 13
    fc68 => f768  the 'c' (b1100) change to '7' (b0111).
    maybe disk bit overturn, maybe lvm has bug. I don't know & have no idea.


On 9/11/19 5:17 PM, Gang He wrote:
> Hello List,
> Our user encountered a meta-data corruption problem, when run pvresize 
> command after upgrading to LVM2 v2.02.180 from v2.02.120.
> The details are as below,
> we have following environment:
> - Storage: HP XP7 (SAN) - LUN's are presented to ESX via RDM
> - VMWare ESXi 6.5
> - SLES 12 SP 4 Guest
> Resize happened this way (is our standard way since years) - however - this 
> is our first resize after upgrading SLES 12 SP3 to SLES 12 SP4 - until this 
> upgrade, we
> never had a problem like this:
> - split continous access on storage box, resize lun on XP7
> - recreate ca on XP7
> - scan on ESX
> - rescan-scsi-bus.sh -s on SLES VM
> - pvresize  ( at this step the error happened)
> huns1vdb01:~ # pvresize /dev/disk/by-id/scsi-360060e80072a660000302a6600003274

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