can't attach

Please include any bcache messages printed in dmesg when this happens.

Post by Stan Hoeppner
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument
What's the problem here?
Thanks,
Stan
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Stan Hoeppner

2014-10-03 20:50:01 UTC

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found

For completeness, these are the steps are performed, soup to nuts:

# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register

# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1

# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0

# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0

# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A

# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet

# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Slava Pestov

2014-10-03 20:57:03 UTC

It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Stan Hoeppner

2014-10-03 21:14:00 UTC

I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.

bash: echo: write error: Invalid argument

How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?

FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.

I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.

Thanks,
Stan

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Slava Pestov

2014-10-03 21:21:13 UTC

Hi Stan,

The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.

Slava

Post by Stan Hoeppner
I assumed it did not go fine due to the immediate error on the echo command. FYI, this is my first attempt at bcache.
bash: echo: write error: Invalid argument
How can I confirm both dm-4 and dm-7 (bcache0 and bcache1) are both attached and that bcache is running?
FYI, this is my first attempt at bcache, so I'm following the instructions precisely. Also, dm-4 and dm-7 are 44 TB RAID6 LUNs. If my testing shows substantial benefit in decreasing RMW we will be looking at deploying bcache with one or more mirrored pairs of SSDs to 14 of these arrays. That's per system. And we'll be deploying 100s of such systems.
I emailed Kent's gmail address about this about a month ago and never received a response. At some point, probably next year some time, the company I'm working for may want to contract with him for a short time before moving into production with this.
Thanks,
Stan

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Stan Hoeppner

2014-10-03 21:37:46 UTC

Probably so. I'm working from:
https://www.kernel.org/doc/Documentation/bcache.txt

Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...

Thanks,
Stan

Post by Slava Pestov
Hi Stan,
The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.
Slava

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Slava Pestov

2014-10-03 21:49:32 UTC

Hi Stan,

It looks like those docs are out of date. Echoing the names of the
cache and backing devices to 'register' is sufficient. 'attach' is for
adding a new backing device to an existing cache set after the fact.

Slava

Post by Stan Hoeppner
https://www.kernel.org/doc/Documentation/bcache.txt
Do I need to manually register the backing devices? I formatted the LUNs and the SSD on the same command line. Instructions above say you don't need to register manually if doing it that way. Also, I'm not using the udev rules, but doing everything manually at this point. And there is a reason for that. I don't have complete control/access to the development system. The rootfs is NFS mounted read only, and changes such as udev rules take days...
Thanks,
Stan

Post by Slava Pestov
Hi Stan,
The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.
Slava

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Stan Hoeppner

2014-10-03 22:05:11 UTC

Would you please kindly provide a link to more recent docs? I notice I have a stripe_size file that's not mentioned in any of the docs I have linked, including the official evil pirate docs. I know Kent was working on stripe write optimization in newer versions. I'm on kernel 3.12.26, so that must have been back ported.

Thanks,
Stan

Post by Slava Pestov
Hi Stan,
It looks like those docs are out of date. Echoing the names of the
cache and backing devices to 'register' is sufficient. 'attach' is for
adding a new backing device to an existing cache set after the fact.
Slava

Post by Slava Pestov
Hi Stan,
The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.
Slava

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Slava Pestov

2014-10-03 22:08:28 UTC

Hi Stan,

Is there any chance you could upgrade to a more recent kernel? As far
as I know, recent bcache bug fixes are not being backported to older
kernels because bcache depends on some block layer changes that went
in more recently.

Post by Stan Hoeppner
Would you please kindly provide a link to more recent docs? I notice I have a stripe_size file that's not mentioned in any of the docs I have linked, including the official evil pirate docs. I know Kent was working on stripe write optimization in newer versions. I'm on kernel 3.12.26, so that must have been back ported.
Thanks,
Stan

Post by Slava Pestov
Hi Stan,
The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.
Slava

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument

Stan Hoeppner

2014-10-03 22:43:52 UTC

I'd actually just like information on how to confirm caching is enabled and working for both of the LUNs mentioned in my long output below. I'm seeing normal write behavior for one, and odd behavior (2x streaming throughput and some apparent permissions issues) for the other. This leads me to believe bcache is active for the 2nd LUN and is causing some breakage while the first LUN is not being cached.

Thanks,
Stan

Post by Slava Pestov
Hi Stan,
Is there any chance you could upgrade to a more recent kernel? As far
as I know, recent bcache bug fixes are not being backported to older
kernels because bcache depends on some block layer changes that went
in more recently.

Post by Slava Pestov
Hi Stan,
The 'register' command attaches the backing device, you don't need to
do the separate 'attach' step. Perhaps the instructions you are
following are out of date.
Slava

Post by Slava Pestov
It looks like everything went fine, what is the problem?

Post by Slava Pestov
Please include any bcache messages printed in dmesg when this happens.

[87579.418945] bcache: bch_cached_dev_attach() Can't attach dm-4: already attached
[87579.418947] bcache: __cached_dev_store() Can't attach 8246b830-95d4-420d-aff8-894efc348801
[87579.418947] : cache set not found
# wipefs -a /dev/dm-4
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/dm-7
4 bytes [58 46 53 42] erased at offset 0x0 (xfs)
# wipefs -a /dev/sdc
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc
Already a bcache device on /dev/sdc, overwrite with --wipe-bcache
# ./make-bcache -B /dev/dm-4 /dev/dm-7 -C /dev/sdc --wipe-bcache
UUID: 501486ea-d614-4a32-a137-bc8e004fcb85
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 0
nbuckets: 761856
block_size: 1
bucket_size: 1024
nr_in_set: 1
nr_this_dev: 0
first_bucket: 1
UUID: 261cf532-ca93-45b7-a8fb-1eff57078953
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
UUID: eeca31ab-a632-4d7b-94f6-35e9b878344f
Set UUID: 8246b830-95d4-420d-aff8-894efc348801
version: 1
block_size: 1
data_offset: 16
# echo /dev/dm-4 > /sys/fs/bcache/register
# echo /dev/dm-7 > /sys/fs/bcache/register
# echo /dev/sdc > /sys/fs/bcache/register
# ls -la /dev/b*
brw-rw---- 1 root disk 253, 0 Oct 3 14:39 /dev/bcache0
brw-rw---- 1 root disk 253, 1 Oct 3 14:39 /dev/bcache1
# mkfs.xfs /dev/bcache0
meta-data=/dev/bcache0 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mkfs.xfs /dev/bcache1
meta-data=/dev/bcache1 isize=256 agcount=44, agsize=268435455 blks
= sectsz=512 attr=2, projid32bit=0
data = bsize=4096 blocks=11709285374, imaxpct=5
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0
log =internal log bsize=4096 blocks=521728, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache0 /mnt/V1A
# mount -o inode64,nobarrier,noatime,nodiratime /dev/bcache1 /mnt/V2A
# ls -la /sys/fs/bcache
total 0
drwxr-xr-x 3 root root 0 Oct 3 14:39 .
drwxr-xr-x 6 root root 0 Oct 2 16:32 ..
drwxr-xr-x 7 root root 0 Oct 3 14:50 8246b830-95d4-420d-aff8-894efc348801
--w------- 1 root root 4096 Oct 3 14:39 register
--w------- 1 root root 4096 Oct 3 14:50 register_quiet
# echo 8246b830-95d4-420d-aff8-894efc348801 > /sys/block/bcache0/bcache/attach
bash: echo: write error: Invalid argument