<\/p>\n
I had to recover LVM metadata from one physical volume and here are the steps I followed. \u00a0I am not sure why I got this situation, I’ve used LVM for a long time and this is the only one that I have to recover the metadata. The physical volume was backed by ISCSI lun.<\/p>\n
Running pvdisplay command showed\u00a0as no LVM volume:<\/p>\n
$ sudo pvdisplay \/dev\/mapper\/26a326a6471427270\r\nNo physical volume label read from \/dev\/mapper\/26a326a6471427270\r\nFailed to read physical volume "\/dev\/mapper\/26a326a6471427270"\r\n<\/pre>\n<\/p>\n
ISCSI session was OK:<\/p>\n
$ sudo iscsiadm -m session\r\n\r\ntcp: [25] 172.16.68.51:3260,1 iqn.2012-12:backups\r\ntcp: [26] 172.16.68.151:3260,1 iqn.2012-12:backups\r\ntcp: [27] 172.16.64.10:3260,1 iqn.2012-12:backups\r\ntcp: [28] 172.16.66.10:3260,1 iqn.2012-12:backups<\/pre>\n<\/p>\n
multipath\u00a0detected the device paths OK:<\/p>\n
26a326a6471427270 dm-11 SCST_BIO,j2jdqBrpZ2sYmXO3\r\nsize=13T features='0' hwhandler='0' wp=rw\r\n`-+- policy='round-robin 0' prio=0 status=active\r\n|- 30:0:0:0 sdaf 65:240 active ready running\r\n|- 28:0:0:0 sdah 66:16 active ready running\r\n|- 29:0:0:0 sdag 66:0 active ready running\r\n`- 31:0:0:0 sdai 66:32 active ready running<\/pre>\n<\/p>\n
$ sudo dmsetup ls --tree\r\nvgsatar6_C02-ovznhshare05 (253:52)\r\n\u2514\u250026a326a6471427270 (253:11)\r\n\u251c\u2500 (66:32)\r\n\u251c\u2500 (66:0)\r\n\u251c\u2500 (66:16)\r\n\u2514\u2500 (65:240)\r\n<\/pre>\n<\/p>\n
$ sudo ls -l \/dev\/vgsatar6_C02\/ovznhshare05\r\n\r\nlrwxrwxrwx 1 root root 8 ene 21 17:06 \/dev\/vgsatar6_C02\/ovznhshare05 -> ..\/dm-52\r\n<\/pre>\n<\/p>\n
Also the device was mounted and running fine:<\/p>\n
$ mount\r\n\r\n\/dev\/mapper\/vgsatar6_C02-ovznhshare05 on \/var\/san\/share05 type ext3 (rw,relatime,errors=continue,barrier=0,data=ordered)\r\n<\/pre>\nBut, I was sure that if the server was restarted\u00a0the device was going to be lost and not mounted again.<\/p>\n
The steps to recover the metadata were as follows:<\/p>\n
umount the device:<\/p>\n
$ sudo umount \/var\/san\/share05<\/pre>\nOpen your last LVM backup for that VG in \/etc\/lvm\/backup. In my case it was\u00a0\/etc\/lvm\/backup\/vgsatar6_C02<\/p>\n
Indentify the UUID for your physical volume in that file:<\/p>\n
<\/p>\n
physical_volumes {\r\n pv0 {\r\n id = "1Babrx-VzKI-7Yav-9hGp-2KX2-DRgT-zdpAql"\r\n device = "\/dev\/mapper\/26a326a6471427270" # Hint only\r\n\r\n status = ["ALLOCATABLE"]\r\n flags = []\r\n dev_size = 27288010752 # 12,707 Terabytes\r\n pe_start = 2048\r\n pe_count = 3331055 # 12,707 Terabytes\r\n }\r\n}<\/pre>\nIn my case the Id was “1Babrx-VzKI-7Yav-9hGp-2KX2-DRgT-zdpAql”.<\/p>\n
Recreate the physical volume again using the information saved in the backup:<\/p>\n
$ sudo pvcreate --uuid "1Babrx-VzKI-7Yav-9hGp-2KX2-DRgT-zdpAql" --restorefile \/etc\/lvm\/backup\/vgsatar6_C02\u00a0\/dev\/mapper\/26a326a6471427270<\/pre>\n<\/p>\n
Restore volume group:<\/p>\n
<\/p>\n
$sudo vgcfgrestore vgsatar6_C02<\/pre>\nActivate logical volume and mount it again:<\/p>\n
<\/p>\n
$ sudo lvchange -ay \/dev\/vgsatar6_C02\/ovznhshare05\u00a0\r\n$ sudo mount \/dev\/vgsatar6_C02\/ovznhshare05\u00a0\/var\/san\/share05<\/pre>\n<\/p>\n
And that’s all, I hope that will help someone.<\/p>\n