[Fedora-directory-users] Error Logging Performance

[Richard Megginson]

David Boreham wrote:
> Roman RATHLER wrote:
>> If I activate error logging for ACL Control Summary or similar, the 
>> machine totaly goes into IO-Wait. It just writes maybe 100K/second 
>> but is totaly unusable any more... From normal 1% CPU Load (on a 2 
>> Way Xeon) it moves to 200% CPU Utilization.
>> Debugging ACLs therefore is nearly impossible on a productive system...
>>
>> We run the Fedora-DS 1.0.4 (fedora-ds-1.0.4-1.RHEL4) on an up2date 
>> CentOS System... Is there any perfomance tuning option like with the 
>> log-buffering for access log. I can't see, why logging kills the 
>> machine!
> Errors often occur before a crash, and therefore the error log
> is flushed to persistent store often in order to improve the chances
> that any message emitted before a crash will be retained.
>
> I seem to remember that buffering can be enabled on the error log
> but I can't remember the details. Probably in the documentation 
> somewhere though.
> I think the underlying code is the same for the error log vs. the 
> access log
> (which is optimized for performance by default) , so it should be 
> possible
> to configure the error log to buffer.
I don't think this is possible.  It looks like only the access log has 
this switch.
>
> Alternatively you could put the error log file on a ramdisk.
Another option is to replace the error log file with a named pipe.  The 
other end of the pipe is connected to a python script that keeps a 
circular log buffer in memory.  The script below allows you to configure 
the size of that buffer, and if you want to use a fifo for the access 
and audit logs.
>
>
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