statikregimen
Apprentice
Joined: 16 Jul 2011
Posts: 173
Location: USA/Michigan
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 Posted: Fri Aug 25, 2017 2:37 pm Post subject: [SOLVED] Recover bcache from previous system? |
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EDIT: A little more google-fu has lead me here https://stackoverflow.com/questions/22820492/how-to-revert-bcache-device-to-regulare-filesystem#23295521
It looks very promising. I am reading it now and will try the suggestion(s), reporting back my findings.
[SOLVED]
| Code: | # losetup -o 8192 /dev/loop0 /dev/your_bcache_backing_dev
# mount /dev/loop0 /mnt/somewhere
# cd /mntsomewhere
# ls
<your data should now be listed here> |
It is up to you what to do with it next. I'm going to back it up and get rid of those gross NTFS partitions, then make a new bcache for my /home directory 
p.s. I still can't get over how 99% of the time, right after I give up and post in forums, I find the solution on my own....
Original post:
Good day,
I recently decided to move from Ubuntu to Gentoo
The machine has two SSDs, split into two mdadm RAID0 arrays.
The first array is for the root partition. On Ubuntu, I was using the 2nd array as cache for a spinning disk.
So my question is: Is it possible to bring the cache+backing drive back online with data in-tact? I've google-fu'ed the crap out of it, but the best I can find is how to cache a device that contains existing data. It's not the end of the world if I can't, which is why I didn't bother backing anything up first. But in retrospect, it would be nice to have that data back...would save me redownloading some big files, and forgot about a couple save games that were on there.
I've tried simply mounting the backing device:
| Code: | # mount /dev/sda2 /media/tmp/
mount: unknown filesystem type 'bcache' |
Recreating the device:
| Code: | # make-bcache -B /dev/sda2
Already a bcache device on /dev/sda2, overwrite with --wipe-bcache |
It apparently doesn't get automatically detected:
| Code: | # ls /dev/bcache*
ls: cannot access '/dev/bcache*': No such file or directory |
I have set in my kernel config:
| Code: |
<*> Block device as cache
[ ] Bcache debugging
[ ] Debug closures |
| Code: | # lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sr0 11:0 1 1024M 0 rom
nvme1n1 259:4 0 119.2G 0 disk
├─nvme1n1p3 259:6 0 59.4G 0 part
│ └─md127 9:127 0 118.7G 0 raid0
└─nvme1n1p2 259:5 0 59.4G 0 part
└─md126 9:126 0 118.7G 0 raid0
├─md126p3 259:9 0 6.9G 0 md [SWAP]
├─md126p1 259:7 0 18.6G 0 md /
└─md126p2 259:8 0 93.1G 0 md
sda 8:0 0 931.5G 0 disk
├─sda2 8:2 0 931.4G 0 part
└─sda1 8:1 0 100M 0 part
nvme0n1 259:0 0 119.2G 0 disk
├─nvme0n1p3 259:3 0 59.4G 0 part
│ └─md127 9:127 0 118.7G 0 raid0
├─nvme0n1p1 259:1 0 512M 0 part /boot
└─nvme0n1p2 259:2 0 59.4G 0 part
└─md126 9:126 0 118.7G 0 raid0
├─md126p3 259:9 0 6.9G 0 md [SWAP]
├─md126p1 259:7 0 18.6G 0 md /
└─md126p2 259:8 0 93.1G 0 md |
| Code: | # fdisk -l /dev/sda
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 206847 204800 100M 7 HPFS/NTFS/exFAT
/dev/sda2 206848 1953523119 1953316272 931.4G 7 HPFS/NTFS/exFAT |
I'm happy to provide any further details if needed.
Thanks in advance! |
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