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-360060e80072a670000302a670000fc68
scsi-360060e80072a670000302a670000fc67
scsi-360060e80072a670000302a670000fc66
scsi-360060e80072a660000302a660000f74c
scsi-360060e80072a660000302a660000f74a
scsi-360060e80072a660000302a660000f749
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 vgpocdbcdb1_r1
#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:
```
#format_text/text_label.c:423 /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 sectors
#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:
pvresize
process_each_pv
_process_pvs_in_vgs
vg_read
vg_read_internal
_vg_read
_vg_update_old_pv_ext_if_needed
+-> pv_needs_rewrite is 1
| set vg->pv_write_list
+-> vg_write
||
\/
vg_write
pv_write //vg->pv_write_list is not empty.
pv->fmt->ops->pv_write
_text_pv_write
lvmcache_foreach_mda(info, _write_single_mda, &baton)
_raw_write_mda_header
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;
}
dev_unset_last_byte(dev);
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:
pre_pvr/scsi-360060e80072a670000302a670000fc68
(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 = "/dev/disk/by-id/scsi-360060e80072a660000302a660000f768"
Wrong!! ^^^^^
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.
Thanks
zhm
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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