[Ocfs2-users] ocfs2 hangs during webserver usage

[Sean Gray]

Why not just setup a syslog server and send all your apache logs to a 
central repository. Here is a quick tutorial 
http://www.oreillynet.com/pub/a/sysadmin/2006/10/12/httpd-syslog.html

Sean

David Johle wrote:
> At 06:32 PM 1/27/2009, jmoseley at corp.xanadoo.com wrote:
>   
>> As others have indicated, I don't think that's going to work very well.
>> You've got two different nodes trying to write to the same file constantly.
>> I would keep each server's log on a locally mounted file system, or simply
>> keep the logs on the OCFS2 filesystem, but have each node write to
>> different log files.
>>
>> Yeah, that makes parsing access_logs slightly more of a problem for
>> producing hit reports, etc, but I think you'll notice performance improve.
>>     
>
>
> Yes, parsing logs is just one good reason for having unified log 
> files -- one of the motivations for using OCFS2 even.  If our 
> statistics program can handle multiple files, then at least having 
> them in a shared directory would be useful.
>
> Another major area this would affect is web site issue 
> troubleshooting which outputs to log files (not the access logs but 
> others).  I can only imagine the complexity of having to deal with 
> locating specific logging information for a site user who is having 
> trouble by going to 5 different nodes to dig through locally stored 
> log files.  Or worse yet, trying to correlate actions of multiple 
> users who are each hitting different nodes!
>
> On that note, these other logs are written to by our aplications 
> running under Tomcat.  I really am not seeing any similar lags for 
> those processes, only from apache.  The only big difference I can see 
> between them is the I/O pattern -- apache is usually 1 line per 
> request as they are serviced, java web apps are more bursts of 
> numerous lines, but not every request.  There is still a non-trivial 
> amount of logging happening for these java apps though, so I am 
> surprised.  In fact, Tomcat itself is configured to log each request 
> with the processing time (used to produce user response time 
> statistics), but those shared logs don't seem to be a point of 
> contention like the apache access logs.
>
> For informational purposes, here are some line counts for logs on our 
> main web site yesterday:
>    1577860 access log
>       1361 error log
>    4887437 web app log
>     340164 processing time log
>    6806822 total
>
> So only about 20% of the requests are handled by Tomcat.  The web app 
> log actually writes 3x as many lines, but overall it's less data 
> (373M vs. 428M) and fewer actual write operations.  This could 
> explain why it is not/less prone to these write delays.
>
>
> I will try changing the logging to use separate files for a day or so 
> to at least see what effect it has with regards to this issue...stay tuned.
>
>
>
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