reading an ex linux bcache disk
Hello,
I have the following problem.
I used bcache on a computer with one hard drive and one small ssd.
(openSUSE 13.2)
this computer broke, it do not boot anymore. I could only recover the hard drive that seems perfectly working - I can read all the partitions but the bcache one.
is there any way to read the bcache partition content? As far as I know, the computer was shut down properly (it broke because somebody walked on it :-).
right now this is only a theoretical question (the problem is real, but there is nothing important on the bcache partition), but what I read on the net let me think this is not a trivial thing. If the disk content can't be recovered, I wont anymore use bcache :-(.
right now I get a "file system unknown" when I try to mount the bcache partition.
thanks for your help
jdd
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Quoted 6 lines · Josep Lladonosa
Quoted 1 line
right now I get a "file system unknown" when I try to mount the
bcache partition.
To mount a bcache partition you need an associated caching device (previous ssd, or a newly created), if I am not wrong. At least I had to do this to access to one.
could I use (for a moment only) an usb device? it's not for performance, only to access the partition. It seems to be possible for new install?
thanks
jdd
Hello jdd,
Quoted 8 lines · you
Hello,
I have the following problem.
I used bcache on a computer with one hard drive and one small ssd.
(openSUSE 13.2)
Quoted 7 lines
this computer broke, it do not boot anymore. I could only recover the hard drive that seems perfectly working - I can read all the partitions but the bcache one.
is there any way to read the bcache partition content? As far as I know, the computer was shut down properly (it broke because somebody walked on it :-).
You can access the contents of the bcache volume without using a cache partition at all. All you'll need is a kernel that supports bcache and one or two commands from the terminal. I don't have time to go into details, but probably it will be something like:
echo 1 > /sys/block/sda/sda3/bcache/running
(Taken from https://wiki.archlinux.org/index.php/Bcache, you may want to look
there or at https://www.kernel.org/doc/Documentation/bcache.txt for more
information.)
Pavel Goran
Quoted 3 lines · Pavel Goran
You can access the contents of the bcache volume without using a cache partition at all. All you'll need is a kernel that supports bcache and one or two commands from the terminal.
good, because I can't ake the install of bcahe work with the old disk :-(
I don't have time to go into details, but
Quoted 7 lines
probably it will be something like:
echo 1 >
/sys/block/sda/sda3/bcache/running(Taken from https://wiki.archlinux.org/index.php/Bcache, you may want to look
there or at https://www.kernel.org/doc/Documentation/bcache.txt for more
information.)
I will read this now
thanks
jdd
Le 28/05/2015 11:09, Pavel Goran a écrit :
got it!
Quoted 1 line
echo 1 >
/sys/block/sda/sda3/bcache/running
was the key :-)! thanks!
the manual says:
"make-bcache has the ability to format multiple devices at the same time"
but then:
To get started:
mkfs.ext4 /dev/bcache0
so the word "format" is not used always with the same meaning (for me, formatting is creating a file system).
gladfully, make-bcache do *not* format the partition :-)
What I did:
* install a new system elsewhere (same distro I used with bcache). kernel 3.16.7 install bcache-tools
make-bcache -B /dev/sda8 (the old bcache backing)
tried to find /sys/block/sda/bcache, but it do not exist. Your example made me think the manual lacked a level, it have to be sys/block/sda/sda8/bcache
echo 1 > /sys/block/sda/sda3/bcache/running
and then /dev/bcache0 shows up!
mount /dev/bcache0 /mnt allows me to access the files on the partition
so good, thanks!
jdd