[Gluster-users] question about info and info.tmp
Atin Mukherjee
amukherj at redhat.com
Fri Nov 25 07:46:25 UTC 2016
On Fri, Nov 25, 2016 at 1:14 PM, songxin <songxin_1980 at 126.com> wrote:
> Hi Atin,
> It seems that this workaround should be done by manual.
> Is that right?
> And even the files in bricks/* may be empty too.
>
Yes, that's right
>
> Do you have a workaround, which is implemented in glusterfs code？
>
Workaround is by nature manual and anything to be done through code should
be considered as fix not work around :)
>
> Thanks,
> Xin
>
>
>
>
>
> 在 2016-11-25 15:36:29，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>
>
>
> On Fri, Nov 25, 2016 at 12:06 PM, songxin <songxin_1980 at 126.com> wrote:
>
>> Hi Atin,
>> Do you mean that you have the workaround applicable now？
>> Or it will take time to design the workaround？
>>
>> If you have workaround now, could you share it to me ?
>>
>
> If you end up in having a 0 byte info file you'd need to copy the same
> info file from other node and put it there and restart glusterd.
>
>
>>
>> Thanks,
>> Xin,
>>
>>
>>
>>
>>
>> 在 2016-11-24 19:12:07，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>
>> Xin - I appreciate your patience. I'd need some more time to pick this
>> item up from my backlog. I believe we have a workaround applicable here too.
>>
>> On Thu, 24 Nov 2016 at 14:24, songxin <songxin_1980 at 126.com> wrote:
>>
>>>
>>>
>>>
>>> Hi Atin,
>>> Actually, the glusterfs is used in my project.
>>> And our test team find this issue.
>>> So I want to make sure that whether you plan to fix it.
>>> if you have plan I will wait you because your method shoud be better
>>> than mine.
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>> 在 2016-11-21 10:00:36，"Atin Mukherjee" <atin.mukherjee83 at gmail.com> 写道：
>>>
>>> Hi Xin,
>>>
>>> I've not got a chance to look into it yet. delete stale volume function
>>> is in place to take care of wiping off volume configuration data which has
>>> been deleted from the cluster. However we need to revisit this code to see
>>> if this function is anymore needed given we recently added a validation to
>>> fail delete request if one of the glusterd is down. I'll get back to you on
>>> this.
>>>
>>> On Mon, 21 Nov 2016 at 07:24, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi Atin,
>>> Thank you for your support.
>>>
>>> And any conclusions about this issue?
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>>
>>>
>>>
>>> 在 2016-11-16 20:59:05，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Tue, Nov 15, 2016 at 1:53 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> ok, thank you.
>>>
>>>
>>>
>>>
>>> 在 2016-11-15 16:12:34，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Tue, Nov 15, 2016 at 12:47 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>>
>>> Hi Atin,
>>>
>>> I think the root cause is in the function glusterd_import_friend_volume
>>> as below.
>>>
>>> int32_t
>>> glusterd_import_friend_volume (dict_t *peer_data, size_t count)
>>> {
>>> ...
>>> ret = glusterd_volinfo_find (new_volinfo->volname,
>>> &old_volinfo);
>>> if (0 == ret) {
>>> (void) gd_check_and_update_rebalance_info (old_volinfo,
>>> n
>>> ew_volinfo);
>>> (void) glusterd_delete_stale_volume (old_volinfo,
>>> new_volinfo);
>>> }
>>> ...
>>> ret = glusterd_store_volinfo (new_volinfo,
>>> GLUSTERD_VOLINFO_VER_AC_NONE);
>>> if (ret) {
>>> gf_msg (this->name, GF_LOG_ERROR, 0,
>>> GD_MSG_VOLINFO_STORE_FAIL, "Failed to store "
>>> "volinfo for volume %s", new_volinfo->volname);
>>> goto out;
>>> }
>>> ...
>>> }
>>>
>>> glusterd_delete_stale_volume will remove the info and bricks/* and the
>>> glusterd_store_volinfo will create the new one.
>>> But if glusterd is killed before rename the info will is empty.
>>>
>>> And glusterd will start failed because the infois empty in the next time
>>> you start the glusterd.
>>>
>>> Any idea， Atin？
>>>
>>>
>>> Give me some time, will check it out, but reading at this analysis looks
>>> very well possible if a volume is changed when the glusterd was done on
>>> node a and when the same comes up during peer handshake we update the
>>> volinfo and during that time glusterd goes down once again. I'll confirm it
>>> by tomorrow.
>>>
>>>
>>> I checked the code and it does look like you have got the right RCA for
>>> the issue which you simulated through those two scripts. However this can
>>> happen even when you try to create a fresh volume and while glusterd tries
>>> to write the content into the store and goes down before renaming the
>>> info.tmp file you get into the same situation.
>>>
>>> I'd really need to think through if this can be fixed. Suggestions are
>>> always appreciated.
>>>
>>>
>>>
>>>
>>> BTW, excellent work Xin!
>>>
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>> 在 2016-11-15 12:07:05，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Tue, Nov 15, 2016 at 8:58 AM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi Atin,
>>> I have some clues about this issue.
>>> I could reproduce this issue use the scrip that mentioned in
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1308487 .
>>>
>>>
>>> I really appreciate your help in trying to nail down this issue. While I
>>> am at your email and going through the code to figure out the possible
>>> cause for it, unfortunately I don't see any script in the attachment of the
>>> bug. Could you please cross check?
>>>
>>>
>>>
>>> After I added some debug print,which like below, in glusterd-store.c and
>>> I found that the /var/lib/glusterd/vols/xxx/info and
>>> /var/lib/glusterd/vols/xxx/bricks/* are removed.
>>> But other files in /var/lib/glusterd/vols/xxx/ will not be remove.
>>>
>>> int32_t
>>> glusterd_store_volinfo (glusterd_volinfo_t *volinfo,
>>> glusterd_volinfo_ver_ac_t ac)
>>> {
>>> int32_t ret = -1;
>>>
>>> GF_ASSERT (volinfo)
>>>
>>> ret = access("/var/lib/glusterd/vols/gv0/info", F_OK);
>>> if(ret < 0)
>>> {
>>> gf_msg (THIS->name, GF_LOG_ERROR, 0, 0, "info is not
>>> exit(%d)", errno);
>>> }
>>> else
>>> {
>>> ret = stat("/var/lib/glusterd/vols/gv0/info", &buf);
>>> if(ret < 0)
>>> {
>>> gf_msg (THIS->name, GF_LOG_ERROR, 0, 0, "stat
>>> info error");
>>> }
>>> else
>>> {
>>> gf_msg (THIS->name, GF_LOG_ERROR, 0, 0, "info
>>> size is %lu, inode num is %lu", buf.st_size, buf.st_ino);
>>> }
>>> }
>>>
>>> glusterd_perform_volinfo_version_action (volinfo, ac);
>>> ret = glusterd_store_create_volume_dir (volinfo);
>>> if (ret)
>>> goto out;
>>>
>>> ...
>>> }
>>>
>>> So it is easy to understand why the info or 10.32.1.144.-opt-lvmdir-c2-
>>> brick sometimes is empty.
>>> It is becaue the info file is not exist, and it will be create by “fd =
>>> open (path, O_RDWR | O_CREAT | O_APPEND, 0600);” in function
>>> gf_store_handle_new.
>>> And the info file is empty before rename.
>>> So the info file is empty if glusterd shutdown before rename.
>>>
>>>
>>>
>>> My question is following.
>>> 1.I did not find the point the info is removed.Could you tell me the
>>> point where the info and /bricks/* are removed?
>>> 2.why the file info and bricks/* is removed?But other files in var/lib/glusterd/vols/xxx/
>>> are not be removed?
>>>
>>>
>>> AFAIK, we never delete the info file and hence this file is opened with
>>> O_APPEND flag. As I said I will go back and cross check the code once again.
>>>
>>>
>>>
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>> 在 2016-11-11 20:34:05，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Fri, Nov 11, 2016 at 4:00 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi Atin,
>>>
>>> Thank you for your support.
>>> Sincerely wait for your reply.
>>>
>>> By the way, could you make sure that the issue, file info is empty,
>>> cause by rename is interrupted in kernel?
>>>
>>>
>>> As per my RCA on that bug, it looked to be.
>>>
>>>
>>>
>>> Thanks,
>>> Xin
>>>
>>> 在 2016-11-11 15:49:02，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Fri, Nov 11, 2016 at 1:15 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi Atin,
>>> Thank you for your reply.
>>> Actually it is very difficult to reproduce because I don't know when there
>>> was an ongoing commit happening.It is just a coincidence.
>>> But I want to make sure the root cause.
>>>
>>>
>>> I'll give it a another try and see if this situation can be
>>> simulated/reproduced and will keep you posted.
>>>
>>>
>>>
>>> So I would be grateful if you could answer my questions below.
>>>
>>> You said that "This issue is hit at part of the negative testing where
>>> while gluster volume set was executed at the same point of time glusterd in
>>> another instance was brought down. In the faulty node we could see
>>> /var/lib/glusterd/vols/<volname>info file been empty whereas the
>>> info.tmp file has the correct contents." in comment.
>>>
>>> I have two questions for you.
>>>
>>> 1.Could you reproduce this issue by gluster volume set glusterd which was brought down?
>>> 2.Could you be certain that this issue is cause by rename is interrupted in kernel?
>>>
>>> In my case there are two files, info and 10.32.1.144.-opt-lvmdir-c2-brick, are both empty.
>>> But in my view only one rename can be running at the same time because of the big lock.
>>> Why there are two files are empty?
>>>
>>>
>>> Could rename("info.tmp", "info") and rename("xxx-brick.tmp", "xxx-brick") be running in two thread?
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>> 在 2016-11-11 15:27:03，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Fri, Nov 11, 2016 at 12:38 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>>
>>> Hi Atin,
>>> Thank you for your reply.
>>>
>>> As you said that the info file can only be changed in the glusterd_store_volinfo()
>>> sequentially because of the big lock.
>>>
>>> I have found the similar issue as below that you mentioned.
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1308487
>>>
>>>
>>> Great, so this is what I was actually trying to refer in my first email
>>> that I saw a similar issue. Have you got a chance to look at
>>> https://bugzilla.redhat.com/show_bug.cgi?id=1308487#c4 ? But in your
>>> case, did you try to bring down glusterd when there was an ongoing commit
>>> happening?
>>>
>>>
>>>
>>> You said that "This issue is hit at part of the negative testing where
>>> while gluster volume set was executed at the same point of time glusterd in
>>> another instance was brought down. In the faulty node we could see
>>> /var/lib/glusterd/vols/<volname>info file been empty whereas the
>>> info.tmp file has the correct contents." in comment.
>>>
>>> I have two questions for you.
>>>
>>> 1.Could you reproduce this issue by gluster volume set glusterd which was brought down?
>>> 2.Could you be certain that this issue is cause by rename is interrupted in kernel?
>>>
>>> In my case there are two files, info and 10.32.1.144.-opt-lvmdir-c2-brick, are both empty.
>>> But in my view only one rename can be running at the same time because of the big lock.
>>> Why there are two files are empty?
>>>
>>>
>>> Could rename("info.tmp", "info") and rename("xxx-brick.tmp", "xxx-brick") be running in two thread?
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>>
>>>
>>> 在 2016-11-11 14:36:40，"Atin Mukherjee" <amukherj at redhat.com> 写道：
>>>
>>>
>>>
>>> On Fri, Nov 11, 2016 at 8:33 AM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi Atin,
>>>
>>> Thank you for your reply.
>>> I have two questions for you.
>>>
>>> 1.Are the two files info and info.tmp are only to be created or changed
>>> in function glusterd_store_volinfo()? I did not find other point in which
>>> the two file are changed.
>>>
>>>
>>> If we are talking about info file volume then yes, the mentioned
>>> function actually takes care of it.
>>>
>>>
>>> 2.I found that glusterd_store_volinfo() will be call in many point by
>>> glusterd.Is there a problem of thread synchronization?If so, one thread may
>>> open a same file info.tmp using O_TRUNC flag when another thread is
>>> writing the info,tmp.Could this case happen?
>>>
>>>
>>> In glusterd threads are big lock protected and I don't see a
>>> possibility (theoretically) to have two glusterd_store_volinfo () calls at
>>> a given point of time.
>>>
>>>
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>> At 2016-11-10 21:41:06, "Atin Mukherjee" <amukherj at redhat.com> wrote:
>>>
>>> Did you run out of disk space by any chance? AFAIK, the code is like we
>>> write new stuffs to .tmp file and rename it back to the original file. In
>>> case of a disk space issue I expect both the files to be of non zero size.
>>> But having said that I vaguely remember a similar issue (in the form of a
>>> bug or an email) landed up once but we couldn't reproduce it, so something
>>> is wrong with the atomic update here is what I guess. I'll be glad if you
>>> have a reproducer for the same and then we can dig into it further.
>>>
>>> On Thu, Nov 10, 2016 at 1:32 PM, songxin <songxin_1980 at 126.com> wrote:
>>>
>>> Hi,
>>> When I start the glusterd some error happened.
>>> And the log is following.
>>>
>>> [2016-11-08 07:58:34.989365] I [MSGID: 100030] [glusterfsd.c:2318:main]
>>> 0-/usr/sbin/glusterd: Started running /usr/sbin/glusterd version 3.7.6
>>> (args: /usr/sbin/glusterd -p /var/run/glusterd.pid --log-level INFO)
>>> [2016-11-08 07:58:34.998356] I [MSGID: 106478] [glusterd.c:1350:init]
>>> 0-management: Maximum allowed open file descriptors set to 65536
>>> [2016-11-08 07:58:35.000667] I [MSGID: 106479] [glusterd.c:1399:init]
>>> 0-management: Using /system/glusterd as working directory
>>> [2016-11-08 07:58:35.024508] I [MSGID: 106514]
>>> [glusterd-store.c:2075:glusterd_restore_op_version] 0-management:
>>> Upgrade detected. Setting op-version to minimum : 1
>>> *[2016-11-08 07:58:35.025356] E [MSGID: 106206]
>>> [glusterd-store.c:2562:glusterd_store_update_volinfo] 0-management: Failed
>>> to get next store iter *
>>> *[2016-11-08 07:58:35.025401] E [MSGID: 106207]
>>> [glusterd-store.c:2844:glusterd_store_retrieve_volume] 0-management: Failed
>>> to update volinfo for c_glusterfs volume *
>>> *[2016-11-08 07:58:35.025463] E [MSGID: 106201]
>>> [glusterd-store.c:3042:glusterd_store_retrieve_volumes] 0-management:
>>> Unable to restore volume: c_glusterfs *
>>> *[2016-11-08 07:58:35.025544] E [MSGID: 101019]
>>> [xlator.c:428:xlator_init] 0-management: Initialization of volume
>>> 'management' failed, review your volfile again *
>>> *[2016-11-08 07:58:35.025582] E [graph.c:322:glusterfs_graph_init]
>>> 0-management: initializing translator failed *
>>> *[2016-11-08 07:58:35.025629] E [graph.c:661:glusterfs_graph_activate]
>>> 0-graph: init failed *
>>> [2016-11-08 07:58:35.026109] W [glusterfsd.c:1236:cleanup_and_exit]
>>> (-->/usr/sbin/glusterd(glusterfs_volumes_init-0x1b260) [0x1000a718]
>>> -->/usr/sbin/glusterd(glusterfs_process_volfp-0x1b3b8) [0x1000a5a8]
>>> -->/usr/sbin/glusterd(cleanup_and_exit-0x1c02c) [0x100098bc] ) 0-:
>>> received signum (0), shutting down
>>>
>>>
>>> And then I found that the size of vols/volume_name/info is 0.It cause
>>> glusterd shutdown.
>>> But I found that vols/volume_name_info.tmp is not 0.
>>> And I found that there is a brick file vols/volume_name/bricks/xxxx.brick
>>> is 0, but vols/volume_name/bricks/xxxx.brick.tmp is not 0.
>>>
>>> I read the function code glusterd_store_volinfo () in glusterd-store.c .
>>> I know that the info.tmp will be rename to info in function
>>> glusterd_store_volume_atomic_update().
>>>
>>> But my question is that why the info file is 0 but info.tmp is not 0.
>>>
>>>
>>> Thanks,
>>> Xin
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Gluster-users mailing list
>>> Gluster-users at gluster.org
>>> http://www.gluster.org/mailman/listinfo/gluster-users
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> ~ Atin (atinm)
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Gluster-users mailing list
>>> Gluster-users at gluster.org
>>> http://www.gluster.org/mailman/listinfo/gluster-users
>>>
>>> --
>>> --Atin
>>>
>>> --
>> - Atin (atinm)
>>
>>
>>
>>
>>
>
>
>
> --
>
> ~ Atin (atinm)
>
>
>
>
>
--
~ Atin (atinm)
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