Access ReadyNAS RNDU2000 mirrored drive directly from Linux.

[WallyZ21]

Also posted in Ubuntu Forum (http://ubuntuforums.org/showthread.php?t=2272848)
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Drive is one from a mirrored pair out of a ReadyNAS RNDU2000 (2 drive unit). I assume this drive uses 16K file system block size.

I have it attached via a USB<->SATA adapter. (tableau write blocker)

Fdisk sees the device as /dev/sdb1 (GPT)

# file -sL /dev/sdb1
/dev/sdb1:Linux Software Raid version 1.2 (1) UUID=d0...b0 name=A0...3A:0 level=1 disks=2

Attempted to reassemble from one drive (force assemble with only one member with --run):

# mdadm --assemble --run /dev/md0 /dev/sdb1
mdadm: cannot re-read metadata from /dev/sdb1 - aborting

Attempted normal mount:

# mount -o ro /dev/sdb1 /mnt/drive
mount: unknown filesystem type 'linux_raid_member'

Attempted to fuse mount drive:

# mkdir /mnt/drive
# fuseext2 -o ro,allow_other /dev/sdb1 /mnt/drive
... Probe failed [main (fuse-ext2.c:347)]

Tried to scan for volume groups:

# vgscan
...
No volume groups found

I'm using Ubuntu 14.04LTS
fuse-ext2 version '0.4', fuse_version:'29'
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I have also tried the Ubuntu9.10 VMware image referred to in these forums (http://www.readynas.com/forum/viewtopic.php?f=11&t=35153&start=105#p275675)
without any success.

The drive (both drives) is working in the ReadyNAS unit but that is not my issue!

Any ideas how I can mount and access this drive from Linux?

[mdgm-ntgr]

The RNDU2000 is the Ultra 2, for which the procedure to attempt to recover data using Linux is different to that used for Sparc ReadyNAS.

For the Ultra 2 you could do e.g.

# mdadm --assemble --scan
# vgscan
# vgchange -a y
# mount -o ro /dev/c/c/ /mnt/drive

Note the steps above do not include checking disk health, the RAID superblock etc. which would be advisable if you don't know what state the array is in.

[WallyZ21]

Thanks for the reply:

#mdadm --assemble --scan
mdadm: cannot re-read metadata from /dev/sdb3 - aborting
mdadm: cannot re-read metadata from /dev/sdb2 - aborting
mdadm: cannot re-read metadata from /dev/sdb1 - aborting
mdadm: No arrays found in config file or automatically

I tried this on both drives!

I must mention at this point the drive is write blocked (read only).

[mdgm-ntgr]

Well the array is clearly not in a good state then.

I assume you have no backup?

Have you checked the health of the disks?

There must be a reason the disks have gone read-only.

[WallyZ21]

No the contrary, the array is in a perfect state. This is an exercise to access a perfectly working array from Linux.

Once I figure the correct commands for a known working array I will move onto faulty arrays.

[mdgm-ntgr]

Perhaps try a different adapter to connect the disk to your PC?

[WallyZ21]

mdgm wrote:
Well the array is clearly not in a good state then. I assume you have no backup? Have you checked the health of the disks? There must be a reason the disks have gone read-only.

I apologize and you may after all be right. I wasn't paying close enough attention to the output of file -sL and I have found something weird in the setup.

There are 3 partitions on each disk.

file -sL reports /dev/sdb1 is level=1 disks=2
file -sL reports /dev/sdb2 is level=1 disks=2
file -sL reports /dev/sdb3 is level=5 disks=2

Level 5? I didn't think the ULTRA 2000 (2 disk unit) supported level 5.

I must have broken it somehow which is unlikely as I tested the USB<->SATA write blocker.

So to find out if it is actually still working I am going to plug the drives back into the NAS unit and fire it up!!!

[WallyZ21]

Plug the drives back into the ULTRA 2 and it starts up fine and I can access all the shares.

Back to square one!!!

So how can I access these drives (with the weird RAID 5 setup) from Linux?

[mdgm-ntgr]

It uses that "weird RAID 5 setup" to enable expansion from 2 disks to 3 in systems that support that.

It sounds like you should try a different USB to SATA adapter or better yet connect the disks to internal SATA ports and boot off a Linux Live CD

[StephenB]

Many older USB2 adapters don't support drives > 2 TB.

[WallyZ21]

StephenB wrote:
Many older USB2 adapters don't support drives > 2 TB.

Some don't!

But this one has been tested (by me) up to 4TB.

And the two drives in question are only 1.5TB anyway!!!