On Sun, Jul 8, 2012 at 2:42 AM, Kent Overstreet [off-list ref] wrote:

On Wed, Jul 04, 2012 at 11:15:32AM +0200, Alain Spineux wrote:

quoted

Hi

I'm trying to unregister disks to unload the bcache module and reuse
the disk for other tests.

Can someone tell me how to unload module bcache after having run these command ?

You'd use either unregister or stop (in the various bcache directories,
depending on whether you just wanted to stop/unregister a backing device
or cache set) and then you ought to be able to rmmod it.

I should test that though, I wouldn't be surprised if something isn't
completely working.

YES !  stop is working !

Thanks Kent

Here is a kind of getting started

first load the bcache module
# modprobe bcache

I created a cache device on /dev/sdb1
# ./make-bcache -C -b512k -w4k --writeback /dev/sdb1

# and a backing device on /dev/sdz1
./make-bcache -B /dev/sdz1

# ./probe-bcache /dev/sdb1
5f42bdd1-4342-4ab6-8dda-855989a09604: UUID="" TYPE="bcache"

# ./probe-bcache /dev/sdz1
6bbac9a4-afbd-4d40-9562-cdd290622c5d: UUID="" TYPE="bcache"

I register the backed device
# echo /dev/sdb1 >/sys/fs/bcache/register

This create /dev/bcache0 thap map /dev/sdz1
except for the first blocks to avoid to use sdz1 instead of bcache0
ATTN bcache0 is not yet attached to any cache device !

I create a "cache set"
# echo /dev/sdz1  >/sys/fs/bcache/register

# ls /sys/fs/bcache/
887d3bb6-0161-4e54-b9d8-801de9f7df83  register  register_quiet

"887d3bb6-0161-4e54-b9d8-801de9f7df83"
is the uuid of the "cache set" composed by the caching device /dev/sdb1


now I attach /dev/sdz1 to this cache set
# echo "887d3bb6-0161-4e54-b9d8-801de9f7df83" >
/sys/block/sdz/sdz1/bcache/attach

I want to activate writeback
# echo writeback > /sys/block/bcache0/bcache/cache_mode

and ask bcache to bypasse the cache when I write more than
64k of sequential data. Default is 4M
# echo 64k > /sys/block/sdz/sdz1/bcache/sequential_cutoff

to stop bcache0
# echo 1 >  /sys/block/sdz/sdz1/bcache/stop

to stop the cache set
# echo 1 > /sys/fs/bcache/887d3bb6-0161-4e54-b9d8-801de9f7df83/stop

An finally unload the module
# modprobe -r bcache

quoted

Thanks.

#first load module
# modprobe bcache

I created a cache device on /dev/sdb1
# ./make-bcache -C -b512k -w4k --writeback /dev/sdb1

and a backing device on /dev/sdz.
# ./make-bcache -B /dev/sdz

# ./probe-bcache /dev/sdb1
5f42bdd1-4342-4ab6-8dda-855989a09604: UUID="" TYPE="bcache"

# ./probe-bcache /dev/sdz
6bbac9a4-afbd-4d40-9562-cdd290622c5d: UUID="" TYPE="bcache"


I then registered them by:
# echo /dev/sdb1 >/sys/fs/bcache/register
# echo /dev/sdz  >/sys/fs/bcache/register

I have /dev/bcache0.
/dev/bcache0 maps /dev/sdz except the first blocks
/dev/bcache0 is not yet cached by anything

# ls /sys/fs/bcache/
887d3bb6-0161-4e54-b9d8-801de9f7df83  register  register_quiet

"887d3bb6-0161-4e54-b9d8-801de9f7df83"
is the id of the bcache "pool" composed by the only caching device /dev/sdb1

# now I attach /dev/sdz to this pool
echo "887d3bb6-0161-4e54-b9d8-801de9f7df83" > /sys/block/sdz/bcache/attach



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Alain Spineux                   |  aspineux gmail com
Monitor your iT & Backups |  http://www.magikmon.com
Free Backup front-end       | http://www.magikmon.com/mksbackup
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