On 2017-09-19 14:33, Andrei Borzenkov wrote:
19.09.2017 14:49, Senén Vidal Blanco пишет:
Perfect!! Just what I was looking for.
Sorry for the delay, because before doing so, I preferred to test to see if it
actually worked.
I have a doubt. The system works perfectly, but at the time of deleting the
writing disk and merging the data on the read-only disk I fail to understand
the process.
I have tried to remove the seed bit on disk A and delete the write B as you
mention, and so move the data to A, but tells me that disk B does not exist.
These are the orders I have made:
md127-> A
md126-> B
btrfstune -S 0 /dev /md127
mount /dev/md127 /mnt (I mount this disk since the md126 gives error)
btrfs device delete /dev/md126 /mnt
ERROR: error removing device '/dev/md126': No such file or directory
Another thing I've tried is to remove disk B without removing the seed bit,
but it gives me the error:
ERROR: error removing device '/dev/md126': unable to remove the only writeable
device.
Any ideas about it?
Yes, sorry about it. Clearing seed flag on device invalidates
filesystem. What you can do, is to rotate devices. I.e. remove
/dev/md126, set seed flag on md127 and add md126 back.
I actually tested it and it works for me.
Same. FWIW, this (like many other things in BTRFS) could stand to be
better documented, especially since it's not likely to be intuitive for
most people.
Thank you very much for the reply.
Greetings.
El martes, 12 de septiembre de 2017 6:34:15 (CEST) Andrei Borzenkov escribió:
11.09.2017 21:17, Senén Vidal Blanco пишет:
I am trying to implement a system that stores the data in a unit (A) with
BTRFS format that is untouchable and that future files and folders created
or modified are stored in another physical unit (B) with BTRFS format.
Each year the new files will be moved to store A and start over.
The idea is that a duplicate of disk A can be made to keep it in a safe
place and that the files stored there can not be modified until the
mixture of (A) and (B) is made.
This can probably be achieved using seed device. Mark original device as
seed and all changes will go to another writable device, similar to
overlay; then remove seed bit from original device, "btrfs device remove
writable" device and it should relocate its content back. Rinse and repeat.
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