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Aspirant

Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

Hi all,

 

I am trying to get data from an old disk previously used in my ReadyNAS - I have an offsite copy of the data but given the current circumstances I can't easily get to it.  Is it possible to mount the disk in a USB caddy and read the BTRFS filesystem as an external disk on the ReadyNAS?  I have only ever prevsiously used NTFS disks as external drives on this unit. 

 

I have tried installing the BTRFS reader on my Win10 laptop so far without success, so I am hoping this will work.  If this doesn't work my next attempt will be mounting the disk as a BTRFS volume on my Linux VM in Virtualbox, but mounting physical disks in VirtualBox is much harder than it should be!

 

I don't intend to ever place this old disk back in the ReadyNAS array, so if mounting this way does something 'destructive' I am ok with that. 

 

Thanks in advance.

 

Model: RN102|ReadyNAS 100 Series 2- Bay
Message 1 of 12
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Guru

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?


@robmash wrote:

 

I am trying to get data from an old disk previously used in my ReadyNAS - I have an offsite copy of the data but given the current circumstances I can't easily get to it.  Is it possible to mount the disk in a USB caddy and read the BTRFS filesystem as an external disk on the ReadyNAS?  I have only ever prevsiously used NTFS disks as external drives on this unit. 

 


What RAID mode were you using in the NAS?

How many disks were in the array?

Message 2 of 12
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Master

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

BTRFS alone isn't enough, you need the MDADM driver as well, as ReadyNAS uses BTRFS on top of MDADM RAID bacause BTRFS RAID is not ready for prime time.  This will only work if your drive was a single JBOD or one of a two-drive RAID1.  Otherwise, you need more drives from the set.

Message 3 of 12
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Aspirant

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

This was a volume which was not part of a RAID group, configured as JBOD.  So, based upon what you say it should work.  However, when I plug the drive in I see nothing.  Is there anything else I need to do?

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Guru

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?


@robmash wrote:

This was a volume which was not part of a RAID group, configured as JBOD.  So, based upon what you say it should work.  However, when I plug the drive in I see nothing.  Is there anything else I need to do?


Did you also install mdadm?  It is needed, even with a jbod disk.  I've never used the windows packages, so I don't know how the commands compare with linux. Another Windows option is to purchase ReclaiMe.  That is expensive though. 

 

How old is this volume?  Note that the OS is on the disk(s), and the NAS does boot from the disks. 

 

If it's fairly recent (6.5.2 firmware or later), then it would be safe to simply power down the NAS, remove the two disks in the RN102 (label by slot), and insert the old disk in slot 1.  When the NAS is powered on, it will attempt to upgrade the OS partition if it is out of date.  After that step, the volume should be accessible.  

 

If the volume predates 6.5.2, then there is some risk that the firmware upgrade would fail. 

 

 

Message 5 of 12
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Master

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

Under the GUI wrapper, ReadyNAS "JBOD" is a one-drive MDADM RAID1.  It's not really RAID since there is only one drive, but MDADM allows it and Netgear takes advantage of it.  I suspect they use it because it makes migration to a real RAID so much easier.  Now, whether the Windows MDADM RAID driver will recognize a "one drive RAID", I cannot say; but it would look similar to a single drive of a two-drive RAID1.  I have plans to do some testing with those drivers, but haven't gotten to it yet.  At least one forum user has reported success with them.

Message 6 of 12
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Prodigy

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

Older thread, but the old Intel ss4200-e also used mdadm and a user recovered an entire raid by simply putting the drives in a system and booting up a ubuntu live cd--the entire volume was automatically there without any work.  I can give you the exact version of the live cd and a link if you would like to give it a shot.

 

Message 7 of 12
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Guru

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?


@SamirD wrote:

Older thread, but the old Intel ss4200-e also used mdadm and a user recovered an entire raid by simply putting the drives in a system and booting up a ubuntu live cd--the entire volume was automatically there without any work.  I can give you the exact version of the live cd and a link if you would like to give it a shot.

 


A live-cd is another option.  But with the ReadyNAS, there generally are some commands needed to mount the array.  

Message 8 of 12
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Prodigy

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

There were supposed to be some commands to mount the Intel's drives too, but those instructions are dated, and when someone just a year ago booted ubuntu because they had to recover their data since their power supply died, the raid was already assembled for him. Smiley Very Happy  It is probably the fastest data recovery I've ever seen from a 'dead' raid unit--took him only 15 minutes to get access to his data again. Smiley Happy

 

Poking around in the ReadyNas OS4 dmesg, it is very similar to the Intel nas units I have so I have some confidence that mounting the raid might be just as easy.  I hope it is because that will be really nice. Smiley Happy

Message 9 of 12
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Guru

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?


@SamirD wrote:

 

Poking around in the ReadyNas OS4 dmesg, it is very similar to the Intel nas units I have so I have some confidence that mounting the raid might be just as easy.  I hope it is because that will be really nice. Smiley Happy


I think it would depend on whether btrfs and mdadm were installed on the live CD or not.  It might also depend on whether the volume has multiple raid groups or not.

 

These commands will work on an ReadyNAS that has been booted into tech support mode. 

# btrfs device scan
# btrfs fi show
# mount -o -ro /dev/md127 /data
Message 10 of 12
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Prodigy

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?

Yep, and this is why I got the exact version of live cd that worked for the person that recovered their Intel nas.  Dunno if it will work for the ReadyNas as I currently don't have a need (and I shouldn't if all the backups hold).

 

Good to know those commands.  If an array doesn't automatically show up with a livecd with btrfs and mdadm support, those same commands should work too.  Are these commands unique to OS4/6?  Or will they work with both?

Message 11 of 12
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Guru

Re: Is it possible to mount a BTRFS partition on an external disk on the ReadyNAS?


@SamirD wrote:

Are these commands unique to OS4/6?  Or will they work with both?


They are unique to OS-6.

 

For OS4 you'd use

# vgscan
# vgchange -a y
# mount -o ro /dev/c/c /c
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