Hi all (This is my first post on this list. I'm still a novice on bcache and proper nettiquete on this list, so apologize for my mistakes) Scenario: several NBD LTSP Fat Clients on (a bit) obsolete hardware kernel 3.11.0-15 on Ubuntu 13.10 /dev/sda1 as local cache device /dev/nbd1 as remote NBD backing bcache device - I've created and registered /dev/sda1 as cache device without problems - To create nbd file to be exported I've typed following sequence: # create an empty file root# dd if=/dev/zero of=bcache_test.img bs=1M count=64 # use it as loop block device root# losetup /dev/loop0 # make it a backing bcache device root# make-bcache -B /dev/loop0 # create a tiny fs on it root# mksquashfs /usr/local /dev/bcache0 -noappend Notice the squashfs: I only need to export fs in read-only mode At this point I can mount file throught bcache w/o problems, so unregister, de-loopize and copy raw bcache_test.img file to nbd server host to be exported. nbd-server is properly configure: I can list, connect and use file: root# nbd-client server -N bcache_test /dev/nbd1 -persist -timeout 60 Negotiation: ..size = 64MB bs=1024, sz=67108864 bytes timeout=60 Using bcache-super-show tells me that file is ok for bcache root# bcache-super-show /dev/nbd1 sb.magic ok sb.first_sector 8 [match] sb.csum AC160BF8DFFB808D [match] sb.version 1 [backing device] dev.label (empty) dev.uuid 936f8be4-7a90-4d2b-b118-5a45a1e37603 dev.sectors_per_block 1 dev.sectors_per_bucket 1024 dev.data.first_sector 16 dev.data.cache_mode 0 [writethrough] dev.data.cache_state 1 [clean] cset.uuid 479b0df0-56d3-4f31-951f-ffb69d8d233b But.... At this point /dev/bcache0 is not created so cannot register it manually with "echo <CSET-UUID> > /sys/block/bcache0/bcache/attach" Item worse: NBD doesn't provide bcache directory under /sys/block/nbd1, so can't execute "echo 1 > /sys/block/nbd1/bcache/running" Notice that If I "dd" /dev/nbd1 to a local file and "losetup" on it, /dev/bcache0 appears automagically attached to /dev/loop0 ¿Any ideas? ¿Does NBD supports bcache in kernel 3.11? ¿If doesn't, any idea on the best way to provide local disk cache for NBD remote devices? Thanks in advance Juan Antonio -- 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
