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.

On Fri, Oct 3, 2014 at 3:05 PM, Stan Hoeppner <[email protected]> wrote:
> 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
>
>
> On 10/03/2014 04:49 PM, Slava Pestov wrote:
>> 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 It looks like those docs are out of date.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
>>
>> On Fri, Oct 3, 2014 at 2:37 PM, Stan Hoeppner <[email protected]> wrote:
>>> 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
>>>
>>>
>>> On 10/03/2014 04:21 PM, Slava Pestov wrote:
>>>> 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 following are out of date.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
>>>>
>>>> On Fri, Oct 3, 2014 at 2:14 PM, Stan Hoeppner <[email protected]> 
>>>> wrote:
>>>>> 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
>>>>>
>>>>>
>>>>>
>>>>> On 10/03/2014 03:57 PM, Slava Pestov wrote:
>>>>>> It looks like everything went fine, what is the problem?
>>>>>>
>>>>>> On Fri, Oct 3, 2014 at 1:50 PM, Stan Hoeppner <[email protected]> 
>>>>>> wrote:
>>>>>>>
>>>>>>> On 10/03/2014 03:37 PM, Slava Pestov wrote:
>>>>>>>> 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
>>>>>>>
>>>>>>>
>>>>>>>> On Fri, Oct 3, 2014 at 1:21 PM, Stan Hoeppner <[email protected]> 
>>>>>>>> wrote:
>>>>>>>>> # 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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