Adopting existing BTRFS drives

I was going to try this in a VM, but I can't get unRAID to boot in VirtualBox... :-/

 

I currently have a server with 2 disks formatted BTRFS in a RAID-1 array.  (The RAID array is through BTRFS' native RAID functionality.)

 

I would like to migrate to unRAID.  I have a 3rd disk I'm going to make a parity disk and would like to convert the existing RAID-1 disks to RAID-5.  Can I easily import my existing disks (and data!) to unRAID and change the RAID level?  How would I go about doing this?

I was going to try this in a VM, but I can't get unRAID to boot in VirtualBox... :-/

 

I currently have a server with 2 disks formatted BTRFS in a RAID-1 array.  (The RAID array is through BTRFS' native RAID functionality.)

 

I would like to migrate to unRAID.  I have a 3rd disk I'm going to make a parity disk and would like to convert the existing RAID-1 disks to RAID-5.  Can I easily import my existing disks (and data!) to unRAID and change the RAID level?  How would I go about doing this?

 

I suspect you might want to read up on what unraid is... Your statement with respect to "converting RAID-1 disks to RAID-5" has got nothing to do with what unraid is or can do.. Or I am understanding you wrong, can you elaborate on what you are trying to accomplish ?

Yeah, unRAID isn't traditional RAID and doesn't implement typical RAID levels.  You'd need to plan on a transition strategy that included formatting your existing drives for use with unRAID.

 

Also while BTRFS is supported in the storage array as well as the cache pool, you'll find the vast majority of folks use XFS in the storage array (or the earlier ReiserFS) due to it's significant maturity and stability over BTRFS.  BTRFS is most commonly used to implement redundancy in the cache pool.

I understand the technical differences between unRAID and real RAID, but in my mind 1 parity disk = RAID-5.  It's easier to think about that way.  :-P

 

I've been following BTRFS for a while now and it seems to be getting to a point of decent maturity where I'm not afraid to use it.  The data I'm storing is mostly my movie collection, which would be a PITA to loose, but not the end of the world since I can just re-rip it.  I have no problem being a BTRFS guinea pig.

 

With all that in mind, would a migration be possible?

I understand the technical differences between unRAID and real RAID, but in my mind 1 parity disk = RAID-5.  It's easier to think about that way.  :-P

 

I've been following BTRFS for a while now and it seems to be getting to a point of decent maturity where I'm not afraid to use it.  The data I'm storing is mostly my movie collection, which would be a PITA to loose, but not the end of the world since I can just re-rip it.  I have no problem being a BTRFS guinea pig.

 

With all that in mind, would a migration be possible?

 

You can call a lemon an orange but it still won;t taste sweet.. But as long as you know what it really is you're fine.

 

Wrt migration: no. disks need to be cleared (completely emptied) prior to be put in the array.

The only possible way you could import them would be in the cache pool.

 

Johnie...  thats a smart one though.. he could import them into the cache pool and then use the mover mechanism to bring them into the array.. at least he would not need to copy stuff himself..

 

 

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For the record, I did some testing and you can in fact import existing BTRFS volumes, with some restrictions.  First of all, the volume can't be part of a RAID; it appears that unRAID will just do a regular mount, and if the volume is degraded a regular mount will fail.  The second restriction is that the data won't be put into a share.  The data will remain in the root of the drive and you will need to manually add it to the share.  This is an easy `mv` command from the command line, but it is a manual step.

The data will remain in the root of the drive and you will need to manually add it to the share.  This is an easy `mv` command from the command line, but it is a manual step.

I haven't tried this, and there isn't enough detail to know exactly what you mean, but this part doesn't quite make sense with the way unRAID user shares work. Every root folder from cache or any array disk is automatically a user share. If there were any root folders on the drive, then they should have become user shares. Maybe you just needed to start/stop stop/start to get the folders picked up as user shares.

unRAID is more like RAID-4 than RAID-5. 

 

 

Sorry If I have missed something and what I think sounds stupid.

But since you have btrfs raid-1

couldn't you "break" it (and keep to seperate copies of data)

and try to assing disk1 as array disk1.

If this works, then you add disk2 as parity, sync and ready!

 

The only drawback is that you will be left with only one copy of data during the above so if the disk with that copy decides to die you will have a problem!