Re: Why does mkcephfs take approximately 30 seconds per osd on ceph 0.51?

[Josh Durgin <josh.durgin@inktank.com>]

On 09/18/2012 04:47 PM, Tren Blackburn wrote:
> On Tue, Sep 18, 2012 at 4:32 PM, Josh Durgin <josh.durgin@inktank.com> wrote:
>> On 09/18/2012 02:23 PM, Tren Blackburn wrote:
>>>
>>> On Tue, Sep 18, 2012 at 2:11 PM, Tren Blackburn <tren@eotnetworks.com>
>>> wrote:
>>>>
>>>> On Tue, Sep 18, 2012 at 1:58 PM, Sage Weil <sage@inktank.com> wrote:
>>>>>
>>>>> On Tue, 18 Sep 2012, Tren Blackburn wrote:
>>>>>>
>>>>>> Hi List;
>>>>>>
>>>>>> I've been working with ceph 0.51 lately, and have noticed this for a
>>>>>> while now, but it hasn't been a big enough issue for me to report.
>>>>>> However today I'm turning up a 192 OSD cluster, and 30 seconds per OSD
>>>>>> adds up pretty quick. For some reason it's taking 30 seconds between
>>>>>> checking the OSD for a pre-existing store:
>>>>>>
>>>>>> 2012-09-18 13:53:28.400590 7fe895d25780 -1 filestore(/var/ceph/disk11)
>>>>>> could not find 23c2fcde/osd_superblock/0//-1 in index: (2) No such
>>>>>> file or directory
>>>>>>
>>>>>> And then actually creating the new store:
>>>>>>
>>>>>> 2012-09-18 13:53:57.371396 7fe895d25780 -1 created object store
>>>>>> /var/ceph/disk11 journal /dev/mapper/vg-journal.disk11 for osd.34 fsid
>>>>>> bca82801-04d7-402e-917f-8023a4b161a8
>>>>>> 2012-09-18 13:53:57.371449 7fe895d25780 -1 auth: error reading file:
>>>>>> /var/ceph/disk11/keyring: can't open /var/ceph/disk11/keyring: (2) No
>>>>>> such file or directory
>>>>>> 2012-09-18 13:53:57.371527 7fe895d25780 -1 created new key in keyring
>>>>>> /var/ceph/disk11/keyring
>>>>>>
>>>>>> I can provide many examples as I'm watching it slowly plod through
>>>>>> currently. Also, the horse power of the server makes no difference.
>>>>>> The servers in question here are dual E5-2600's with 96GB ram and
>>>>>> 12x2TB drives.
>>>>>>
>>>>>> What information can I provide to help debug this? Or is this an
>>>>>> already known issue?
>>>>>
>>>>>
>>>>> If you add -x to the #!/bin/bash line in mkcephfs we can see exactly
>>>>> which
>>>>> command(s) are going slow...
>>>>
>>>>
>>>> It looks like it's the ceph-osd command taking the time:
>>>>
>>>> + /usr/bin/ceph-osd -c /tmp/mkfs.ceph.9006/conf --monmap
>>>> /tmp/mkfs.ceph.9006/monmap -i 000 --mkfs --mkkey
>>>>    HDIO_DRIVE_CMD(identify) failed: Invalid argument
>>>> 2012-09-18 14:08:11.265921 7fb41bd04780 -1 journal check: ondisk fsid
>>>> 00000000-0000-0000-0000-000000000000 doesn't match expected
>>>> aa1f859e-4d3c-4b02-87c5-0190bb51dd48, invalid (someone else's?)
>>>> journal
>>>>    HDIO_DRIVE_CMD(identify) failed: Invalid argument
>>>>    HDIO_DRIVE_CMD(identify) failed: Invalid argument
>>>>    HDIO_DRIVE_CMD(identify) failed: Invalid argument
>>>> 2012-09-18 14:08:11.440522 7fb41bd04780 -1 filestore(/var/ceph/disk01)
>>>> could not find 23c2fcde/osd_superblock/0//-1 in index: (2) No such
>>>> file or directory
>>>> 2012-09-18 14:08:40.424981 7fb41bd04780 -1 created object store
>>>> /var/ceph/disk01 journal /dev/mapper/vg-journal.disk01 for osd.0 fsid
>>>> ad1bcd15-081a-4d6b-abf1-2fcf79764c9b
>>>> 2012-09-18 14:08:40.425032 7fb41bd04780 -1 auth: error reading file:
>>>> /var/ceph/disk01/keyring: can't open /var/ceph/disk01/keyring: (2) No
>>>> such file or directory
>>>> 2012-09-18 14:08:40.425109 7fb41bd04780 -1 created new key in keyring
>>>> /var/ceph/disk01/keyring
>>>>
>>> I managed to attach a strace to the ceph-osd process. Please find it at:
>>>
>>> http://pastebin.com/Tdm2t3jT
>>>
>>> Hopefully it's useful. Please let me know what else I can do to help
>>> with this, as having to wait 1.5 hours for mkcephfs to complete is a
>>> little excessive... ;)
>>>
>>> t.
>>
>>
>> Could you do an strace -tt? That'll tell us where the slowness is.
>>
> Done. http://pastebin.com/Ba9xHZyJ
>
> Please let me know if you need anything else. I've had to re-run the
> mkcephfs anyway...
>
> t.
>

I haven't looked into this in more detail yet, but there are two long
pauses where it's waiting for locks:

Process 20669 attached
16:42:20.994765 futex(0x7fffd339ee7c, FUTEX_WAIT_PRIVATE, 1, NULL) = 0
16:42:43.177930 futex(0x7fffd339ee30, FUTEX_WAKE_PRIVATE, 1) = 0
16:42:43.177989 open("/var/ceph/disk08/magic", O_RDONLY) = -1 ENOENT (No 
such file or directory)
16:42:43.178065 open("/var/ceph/disk08/magic.tmp", 
O_WRONLY|O_CREAT|O_TRUNC, 0644) = 17
...
16:42:43.199460 futex(0x7f3b5457a9d0, FUTEX_WAIT, 20691, NULL) = 0
16:43:12.199531 futex(0x337a92c, FUTEX_CMP_REQUEUE_PRIVATE, 1, 
2147483647, 0x337a8e8, 118) = 2

Josh