Hello I am using Ubuntu 15.10 with latest nightly 4.5 kernel. Ubuntu creates 16 RAM drives as /dev/ram0 - ram16 by default and i am trying to test bcache and use one of these as a cache device. wipefs /dev/sdd wipefs /dev/sdd -a wipefs /dev/ram0 wipefs /dev/ram0 -a make-bcache -B /dev/sdd -C /dev/ram0 At this point there were no errors output but there is also no UUID entry in /sys/fs/bcache/. Only register and register_quiet. bache-super-show correctly prints info about both block and cache devices when queried but when i try to manually attach the cache device with echo cset.uuid > /sys/block/bcache0/bcache/attach i get no error but in dmesg i see bcache: __cached_dev_store() Can't attach 3f2521a6-2103-4e2e-a47d-cc56558e8f7d: cache set not found If i repeat this example but use another sd block device as cache then it works OK. Can anyone confirm if it should be possible to use the ramdisk based block device as a caching device with bcache ? I also tried to use a loop device as cache and that didn't work either.. i got "kernel bug" in dmesg for drivers/md/bcache/super.c:1812. RIP [] cache_alloc.isra.21+0x646/0x670[bcache] Does bcache need the cache device to be a certain block type i.e sd 8 ? Should i be able to use any block device from /proc/devices as a cache device ? The kernel options used for ramdisk are: CONFIG_BLK_DEV_RAM=y CONFIG_BLK_DEV_RAM_COUNT=16 CONFIG_BLK_DEV_RAM_SIZE=65536 CONFIG_BLK_DEV_RAM_DAX=y Thank you. Scott -- To unsubscribe from this list: send the line "unsubscribe linux-bcache" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
