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

[Vladislav Bogdanov]

16.05.2013 02:46, Andrew Beekhof wrote:
> 
> 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 :(

Agree.
I originally made it specific to pengine files.
What do you prefer, simple wrapper in xml.c (f.e.
unlink_and_write_xml_file()) or just add unlink() call to pengine before
it calls write_xml_file()?