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[gailh]

Dear DNS-32x/CH3* expers:

I bought my DNS-323 4 (or 5) years ago. I am not a big computing expert, but I've succeeded formatting two hard disks, installing the Fonz fun_plug, and accessing Volume_1 and Volume_2 from my networked PC.

The following problem showed up a couple of months ago, and I have no clue how to fix it: there was an accidental electricity shutdown. The Dlink-323 system got shut off unexpectedly. When turning it on again, the left amber light on the front stays on, and I can't access (or, on my PC, using Windows Explorer), I can't see Volume_2. Volume_2 contains important data.

I can log in to the Dlink-323 as usual but the opening screen is asking me to format Volume_2. (Which I refrain from, of course).

I think I read somewhere that this can be fixed by telnetting to the unit (using fun_plug), and tweaking (mounting Volume_2 manually? How?)

Your help will be appreciated.

Many TIA

Gail

Update 4-12 13: here is the df -h output:
/ # df -h
Filesystem            Size  Used Avail Use% Mounted on
%root%                9.7M  6.5M  2.8M  70%   /
/dev/ram0             9.7M  6.5M  2.8M  70%  /
/image.cfs            4.5M   4.5M       0 100%  /sys/crfs
/dev/sda2             1.8T   235G  1.6T  13%  /mnt/HD_a2
/dev/sda4             487M   13M  475M   3%  /mnt/HD_a4
/dev/sdb4             487M   11M  476M   3% /mnt/HD_b4
/ #

Interestingly, fdisk does see two hdd's:

/ # fdisk -l

Disk /dev/sda: 2000.3 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start   End            Blocks       Id System
/dev/sda1     1         66           530113+     82 Linux swap
/dev/sda2     131 243201 1952467807+    83 Linux
/dev/sda4     67      130         514080        83 Linux

Disk /dev/sdb: 2000.3 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot Start    End        Blocks        Id System
/dev/sdb1     1           66   530113+        82 Linux swap
/dev/sdb2    131 243201 1952467807+  83 Linux
/dev/sdb4     67       130     514080         83 Linux
/ #

*** -> Update 2: here is (a filtered) output of dmesg, as related to mounting the disks. It seems that there is an IO error when it's trying to mount /dev/sdb2:

SCSI device sda: 3907029168 512-byte hdwr sectors (2000399 MB) drive cache: write back
sda: sda1 sda2 sda4
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
SCSI device sdb: 3907029168 512-byte hdwr sectors (2000399 MB) drive cache: write back
sdb: sdb1 sdb2 sdb4
Attached scsi disk sdb at scsi1, channel 0, id 0, lun 0
Adding 530104k swap on /dev/sda1. Priority:-1 extents:1
Adding 530104k swap on /dev/sdb1. Priority:-2 extents:1
kjournald starting. Commit interval 5 seconds
EXT3 FS on sda4, internal journal
EXT3-fs: recovery complete. mounted filesystem with ordered data mode. kjournald starting. Commit interval 5 seconds
EXT3 FS on sdb4, internal journal
EXT3-fs: recovery complete. mounted filesystem with ordered data mode. kjournald starting. Commit interval 5 seconds
EXT3 FS on sda2, internal journal
EXT3-fs: recovery complete. mounted filesystem with ordered data mode.
SCSI error : <1 0 0 0> return code = 0x8000002
sdb: Current: sense key=0x3 ASC=0x0 ASCQ=0x0 Info fld=0x747bee12
end_request: I/O error, dev sdb, sector 1954278930 JBD: IO error reading journal superblock
EXT3-fs: error loading journal.
EXT2-fs: sdb2: couldn't mount because of unsupported optional features (4).
kjournald starting. Commit interval 5 seconds
EXT3 FS on sda4, internal journal. mounted filesystem with ordered data mode.
EXT3 FS on sdb4, internal journal. mounted filesystem with ordered data mode.

It seems that the system gets an IO error trying to mount /dev/sdb2. All other mounts have succeeded.

[ivan]

Have you considered the fact that you may have a dead disk in that slot?

The safest way to test that is to take out the drive and put it in a USB caddy - or use a USB/SATA adapter then plug it into a computer running the disk manufacturers disk tools and use them to test the drive.

DO NOT let windows write to that drive unless you have an IFS that understands Ext2/3 running or a program that can read the linux file system.

If the tests show your drive is bad then it is a simple matter of obtaining a new drive, letting the unit format it and restoring your data from your tested backup.

[gailh]

@Ivan: thank you for your quick response.
As you see in the update in my edited OP, fdisk -l does see the second disk; so, most probably, it's not dead.
Is it "mounted"? Should I try to mount it? and how?

Many TIA - GailH

Update 2: on boot, the system gets an IO error, trying to mount /dev/sdb2 (see updated dmesg output in the OP). All other mounts succeed.

What to do?

[ivan]

Looking at what you have posted it appears that you have a very sick disk.

Fdisk will 'see' what the firmware of the disk says is there - the test comes when you try and do anything with it. This is showing up as the I/O error for sdb2.  If you try to force that to mount it might do so, depending on the severity of the error, but the results could very well be unpredictable - a sort of last ditch effort.

If any of our clients had those sort of problems we would just dump the disk, replace it and restore from backup.  Experience says that you MIGHT be able to revive the disk with a reformat but you would be very foolish to rely on it, even if it appeared OK, for mission critical data.  Your problem might be that the disk has a dud section of the platter surface and the firmware has run out of spare sectors to relocate those dead sectors to.

You could download the disk manufacturers disk testing tools and run them against the disk and see what the results of that are.  If you are very lucky it might say that a firmware update is advisable, assuming one is available, but that would loose all the data on the drive and I get the impression that is the last thing you want due to lack of current backup.

Somehow I don't think you will be able to save everything on that disk but without the results of the manufacturers disk tools it is hard to say.  For example, the DFT might repair the I/O error and allow you to read what is there but that usually results in some data loss.  This may be acceptable but it would make that drive unreliable for data storage.  We have a box full of such drives that failed just out of warranty and are considered unreliable.