[Pacemaker] [Question and Problem] In vSphere5.1 environment, IO blocking of pengine occurs at the time of shared disk trouble for a long time.

[Andrew Beekhof]

On 15/05/2013, at 6:44 PM, Vladislav Bogdanov <bubble at hoster-ok.com> wrote:

> 15.05.2013 11:18, Andrew Beekhof wrote:
>> 
>> On 15/05/2013, at 5:31 PM, Vladislav Bogdanov <bubble at hoster-ok.com> wrote:
>> 
>>> 15.05.2013 10:25, Andrew Beekhof wrote:
>>>> 
>>>> On 15/05/2013, at 3:50 PM, Vladislav Bogdanov <bubble at hoster-ok.com> wrote:
>>>> 
>>>>> 15.05.2013 08:23, Andrew Beekhof wrote:
>>>>>> 
>>>>>> On 15/05/2013, at 3:11 PM, renayama19661014 at ybb.ne.jp wrote:
>>>>>> 
>>>>>>> Hi Andrew,
>>>>>>> 
>>>>>>> Thank you for comments.
>>>>>>> 
>>>>>>>>> The guest located it to the shared disk.
>>>>>>>> 
>>>>>>>> What is on the shared disk?  The whole OS or app-specific data (i.e. nothing pacemaker needs directly)?
>>>>>>> 
>>>>>>> Shared disk has all the OS and the all data.
>>>>>> 
>>>>>> Oh. I can imagine that being problematic.
>>>>>> Pacemaker really isn't designed to function without disk access.
>>>>>> 
>>>>>> You might be able to get away with it if you turn off saving PE files to disk though.
>>>>> 
>>>>> I store CIB and PE files to tmpfs, and sync them to remote storage
>>>>> (CIFS) with lsyncd level 1 config (I may share it on request). It copies
>>>>> critical data like cib.xml, and moves everything else, symlinking it to
>>>>> original place. The same technique may apply here, but with local fs
>>>>> instead of cifs.
>>>>> 
>>>>> Btw, the following patch is needed for that, otherwise pacemaker
>>>>> overwrites remote files instead of creating new ones on tmpfs:
>>>>> 
>>>>> --- a/lib/common/xml.c  2011-02-11 11:42:37.000000000 +0100
>>>>> +++ b/lib/common/xml.c  2011-02-24 15:07:48.541870829 +0100
>>>>> @@ -529,6 +529,8 @@ write_file(const char *string, const char *filename)
>>>>>       return -1;
>>>>>   }
>>>>> 
>>>>> +    unlink(filename);
>>>> 
>>>> Seems like it should be safe to include for normal operation.
>>> 
>>> Exactly.
>> 
>> Small flaw in that logic... write_file() is not used anywhere.
> 
> Heh, thanks for spotting this.
> 
> I recall write_file() was used for pengine, but some other function for
> CIB. You probably optimized that but forgot to remove unused function,
> that's why I was sure patch is still valid. And I did tests (CIFS
> storage outage simulation) only after initial patch, but not last years,
> that's why I didn't notice the regression - storage uses pacemaker too ;) .
> 
> This should go to write_xml_file() (And probably to other places just
> before fopen(..., "w"), f.e. series).

I've consolidated the code, however adding the unlink() would break things for anyone intentionally symlinking cib.xml from somewhere else (like a git repo).
So I'm not so sure I should make the unlink() change :(