Lost iSCSI LUN

iSCSI related applications
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guszernial
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Posts: 19
Joined: Thu Mar 07, 2019 11:21 am

Lost iSCSI LUN

Post by guszernial »

I have a QNAP TS-473/QTS 5.1 on which I've been storing backups from multiple systems (Win11,Ubuntu 23.10,MacOS 14) on an iSCSI LUN on a 4-disk RAID10 volume. In the past, I accessed the files on the LUN from one of the Windows 11 PC's by connecting to the QNAP using the Microsoft iSCSI initiator, which would connect to the iSCSI target on the QNAP. That connection would create an additional network disk in Windows File Explorer, on which I could view the backup files on the target.

Recently, while the connection still works from the Windows iSCSI initiator, the Windows Explorer network disk no longer shows up, and I can no longer view the backup files on the QNAP iSCSI target using Windows.

So I ssh'd from an Ubuntu PC into the QNAP, and I see multiple mdadm RAID volumes, one of which is /dev/md2, which I think is the location of the backups, as it is the only RAID10 volume on the QNAP, and the capacity of the volume is somewhat less than 4TB, with close to 2TB used, which is about right. I then tried to mount the volume in Ubuntu, but it says the volume is already mounted, though /dev/md2 does not appear in the list generated by the #mount command, or /etc/fstab or /etc/mtab

There's outputs from a couple of the commands I tried upon ssh'ing into the QNAP for reference. I tried a lot of things including trying set the iSCSI volume up for SMB/CIFS sharing - that didn't work either; in fact it might have screwed things up further. I did not erase or reformat the iSCSI volume or the underlying /dev/md2 raid array. I'm hoping someone can provide information or links to enable me to recover my backups.

Thx, Gus

------------------------------------------------------------
[/etc/config] # mdadm --detail /dev/md2
/dev/md2:
Version : 1.0
Creation Time : Tue Apr 16 16:03:25 2019
Raid Level : raid10
Array Size : 3887118336 (3707.04 GiB 3980.41 GB)
Used Dev Size : 1943559168 (1853.52 GiB 1990.20 GB)
Raid Devices : 4
Total Devices : 4
Persistence : Superblock is persistent

Update Time : Wed Jan 17 21:31:38 2024
State : clean
Active Devices : 4
Working Devices : 4
Failed Devices : 0
Spare Devices : 0

Layout : near=2
Chunk Size : 512K

Name : 2
UUID : 723d7933:7acf4935:3a38f73e:3de7fcce
Events : 18704

Number Major Minor RaidDevice State
0 8 35 0 active sync set-A /dev/sdc3
4 8 51 1 active sync set-B /dev/sdd3
2 8 3 2 active sync set-A /dev/sda3
3 8 19 3 active sync set-B /dev/sdb

---------------------------------------------
[/share/CACHEDEV2_DATA/BACKUPS/@Recently-Snapshot] # fdisk /dev/md2
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.


The number of cylinders for this disk is set to 971779584.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/[/share/CACHEDEV2_DATA/BACKUPS/@Recently-Snapshot] # fdisk /dev/md2
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.


The number of cylinders for this disk is set to 971779584.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): p

Disk /dev/md2: 3980.4 GB, 3980409176064 bytes
2 heads, 4 sectors/track, 971779584 cylinders
Units = cylinders of 8 * 512 = 4096 bytes

Device Boo2 FDISK)
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): p

Disk /dev/md2: 3980.4 GB, 3980409176064 bytes
2 heads, 4 sectors/track, 971779584 cylinders
Units = cylinders of 8 * 512 = 4096 bytes

Device Boot Start End Blocks Id System
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dolbyman
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Posts: 34777
Joined: Sat Feb 12, 2011 2:11 am
Location: Vancouver BC , Canada

Re: Lost iSCSI LUN

Post by dolbyman »

QNAP uses block or file LUNs, so neither would be direct mounted to an md block device directly.

So unlcear what you are trying to do
guszernial
Starting out
Posts: 19
Joined: Thu Mar 07, 2019 11:21 am

Re: Lost iSCSI LUN

Post by guszernial »

I’m trying to view and copy/download files on my QNAP iSCSI LUN to another system on my LAN ..lll
User avatar
dolbyman
Guru
Posts: 34777
Joined: Sat Feb 12, 2011 2:11 am
Location: Vancouver BC , Canada

Re: Lost iSCSI LUN

Post by dolbyman »

You need to employ a data recovery specialist that understands LVM structure and ISCSI block storage restoration
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