Volume is down - what to do?

Dear All, 
After a power failure, my NAS326 did not respond and I could not login on NAS on the web. After a factory reset, a managed to get in, but I got the message that the volume is down. (I got two HDDs, but I used only one.)
Based on what I found in earlier posts, I accessed the NAS via SSH and obtained some information. 
Could you please help me interpret what I got? I am a novice.
Is there any way to recover the data?

Thanks,
Gergely














All Replies

  • Mijzelf
    Mijzelf Posts: 2,598  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    Your raid arrays are fine, so I suppose there is a filesystem error in the encapsulated filesystem.
    The 'not mounted' filesystem is /dev/md3. Try a filesystem check:
    su
    e2fsck /dev/md3

    (BTW, when you are using PuTTY for ssh, you can simply select the text with your mouse. Selected text is on the clipboard.)

  • gkovats
    gkovats Posts: 12
    First Anniversary First Comment
    Thank you, Mijzelf!
    I run the commands you suggested and got the following response:

    ~ # e2fsck /dev/md3
    e2fsck 1.42.12 (29-Aug-2014)
    e2fsck: Attempt to read block from filesystem resulted in short read while tryin                             g to open /dev/md3
    Could this be a zero-length partition?
    ~ #

    Do you have any suggestion?
    Gergely
  • Mijzelf
    Mijzelf Posts: 2,598  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    That blockdevice is certainly not zero-length, according to /proc/partitions. Try
    su
    dmesg -c
    e2fsck /dev/md3
    dmesg

    The first 'dmesg -c' will purge the kernel log buffer. The second call to dmesg will show any log messages added as result of e2fsck. I wonder if any I/O errors are logged.

  • gkovats
    gkovats Posts: 12
    First Anniversary First Comment
    There is a buffer I/O error 
    "end_request: I/O error, dev sdb, sector 8261800
    quiet_error: 23 callbacks suppressed
    Buffer I/O error on device md3, logical block 21"


    The result of the last dmesg command follows. Or do you need the result of the first one as well?

    ~ # e2fsck /dev/md3
    e2fsck 1.42.12 (29-Aug-2014)
    e2fsck: Attempt to read block from filesystem resulted in short read while trying to open /dev/md                     3
    Could this be a zero-length partition?


    ~ # dmesg
    ata2.00: exception Emask 0x0 SAct 0x3 SErr 0x0 action 0x0
    ata2.00: irq_stat 0x40000008
    ata2.00: failed command: READ FPDMA QUEUED
    ata2.00: cmd 60/00:08:a0:10:7e/01:00:00:00:00/40 tag 1 ncq 131072 in
             res 41/40:00:a8:10:7e/00:00:00:00:00/00 Emask 0x409 (media error) <F>
    ata2.00: status: { DRDY ERR }
    ata2.00: error: { UNC }
    ata2.00: configured for UDMA/133
    sd 1:0:0:0: [sdb] Unhandled sense code
    sd 1:0:0:0: [sdb]
    Result: hostbyte=0x00 driverbyte=0x08
    sd 1:0:0:0: [sdb]
    Sense Key : 0x3 [current] [descriptor]
    Descriptor sense data with sense descriptors (in hex):
            72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
            00 7e 10 a8
    sd 1:0:0:0: [sdb]
    ASC=0x11 ASCQ=0x4
    sd 1:0:0:0: [sdb] CDB:
    cdb[0]=0x88: 88 00 00 00 00 00 00 7e 10 a0 00 00 01 00 00 00
    end_request: I/O error, dev sdb, sector 8261800
    Buffer I/O error on device md3, logical block 21
    Buffer I/O error on device md3, logical block 22
    Buffer I/O error on device md3, logical block 23
    Buffer I/O error on device md3, logical block 24
    Buffer I/O error on device md3, logical block 25
    Buffer I/O error on device md3, logical block 26
    Buffer I/O error on device md3, logical block 27
    Buffer I/O error on device md3, logical block 28
    Buffer I/O error on device md3, logical block 29
    ata2: EH complete
    ata2.00: exception Emask 0x0 SAct 0x3 SErr 0x0 action 0x0
    ata2.00: irq_stat 0x40000008
    ata2.00: failed command: READ FPDMA QUEUED
    ata2.00: cmd 60/08:08:a8:10:7e/00:00:00:00:00/40 tag 1 ncq 4096 in
             res 41/40:00:a8:10:7e/00:00:00:00:00/00 Emask 0x409 (media error) <F>
    ata2.00: status: { DRDY ERR }
    ata2.00: error: { UNC }
    ata2.00: configured for UDMA/133
    sd 1:0:0:0: [sdb] Unhandled sense code
    sd 1:0:0:0: [sdb]
    Result: hostbyte=0x00 driverbyte=0x08
    sd 1:0:0:0: [sdb]
    Sense Key : 0x3 [current] [descriptor]
    Descriptor sense data with sense descriptors (in hex):
            72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
            00 7e 10 a8
    sd 1:0:0:0: [sdb]
    ASC=0x11 ASCQ=0x4
    sd 1:0:0:0: [sdb] CDB:
    cdb[0]=0x88: 88 00 00 00 00 00 00 7e 10 a8 00 00 00 08 00 00
    end_request: I/O error, dev sdb, sector 8261800
    ata2: EH complete
    ata2.00: exception Emask 0x0 SAct 0x2 SErr 0x0 action 0x0
    ata2.00: irq_stat 0x40000008
    ata2.00: failed command: READ FPDMA QUEUED
    ata2.00: cmd 60/08:08:a8:10:7e/00:00:00:00:00/40 tag 1 ncq 4096 in
             res 41/40:00:a8:10:7e/00:00:00:00:00/00 Emask 0x409 (media error) <F>
    ata2.00: status: { DRDY ERR }
    ata2.00: error: { UNC }
    ata2.00: configured for UDMA/133
    sd 1:0:0:0: [sdb] Unhandled sense code
    sd 1:0:0:0: [sdb]
    Result: hostbyte=0x00 driverbyte=0x08
    sd 1:0:0:0: [sdb]
    Sense Key : 0x3 [current] [descriptor]
    Descriptor sense data with sense descriptors (in hex):
            72 03 11 04 00 00 00 0c 00 0a 80 00 00 00 00 00
            00 7e 10 a8
    sd 1:0:0:0: [sdb]
    ASC=0x11 ASCQ=0x4
    sd 1:0:0:0: [sdb] CDB:
    cdb[0]=0x88: 88 00 00 00 00 00 00 7e 10 a8 00 00 00 08 00 00
    end_request: I/O error, dev sdb, sector 8261800
    quiet_error: 23 callbacks suppressed
    Buffer I/O error on device md3, logical block 21
    ata2: EH complete


    Thanks, 
    Gergely



  • Mijzelf
    Mijzelf Posts: 2,598  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    It's a hardware error.
             res 41/40:00:a8:10:7e/00:00:00:00:00/00 Emask 0x409 (media error) <F>
    For some reason the disk cannot provide blocks 21~29 of md3. (And possibly others neither, but e2fsck didn't try further). So for practical use that disk is dead.

    Do you have valuable and unreplaceable data on that disk?
  • gkovats
    gkovats Posts: 12
    First Anniversary First Comment
    edited May 2022
    Some of it. Family photos and videos.
    is there any chance to recover at least part of them?
    Do you have any suggestions?
    Might Photorec work?
  • Mijzelf
    Mijzelf Posts: 2,598  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    Yes, PhotoRec might work.
    Basically you have 4 options:
    1. Try to recover the filesystem.
    2. Try to recover the files.
    3. Outsource the recovery.
    4. Bin it.
    On 1: It is possible that the filesystem is still more or less OK. e2fsck (and probably mount) didn't look further than block 21~29, because it was unreadable, and they assumed the volume was no bigger. When you create a bit-by-bit copy of the disk using something like [url=https://www.gnu.org/software/ddrescue/]ddrescue[/url], the copy will at least lack block 21~29 (which means they will contain zeros), but there is a chance that e2fsck will be able to repair the filesystem.
    On 2: Any tool which can recover files without help of the filesystem, and without choking in I/O errors, might recover some files. PhotoRec is one of them.
    On 3: That will cost you at least a few 100 Euros, or the equivalent in your local valuta, without guarantee that it will give something. As far as I know there is no 'no cure no pay' in this business.

  • gkovats
    gkovats Posts: 12
    First Anniversary First Comment
    Thank you, Mijzelf!

    I truly appreciate your help.
    I just checked the documentation of ddrescue. It is written there that "Never try to repair a file system on a drive with I/O errors; you will probably lose even more data."
    My understanding is that the HDD has an I/O problem. Could an attempt to recover the filesystem lead to additional data loss? Or am I misunderstanding something?

    Many thanks,
    Gergely
  • Mijzelf
    Mijzelf Posts: 2,598  Guru Member
    First Anniversary 10 Comments Friend Collector First Answer
    My understanding is that the HDD has an I/O problem. Could an attempt to recover the filesystem lead to additional data loss?

    Yes. Although any decent filesystem repair tool will cease action on the first I/O error. That's where ddrescue is for. You copy the disk to another one, which doesn't have I/O errors. (I/O errors are hardware errors. The copy will have zero's at the place where the original had I/O errors, but that sectors are at least normal accessible)

  • gkovats
    gkovats Posts: 12
    First Anniversary First Comment
    Thank you, Mijzelf. I see what can I do. 

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