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 It looks like those docs are out of date.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 following are out of date.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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