Hi,
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!
cheers.roman
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.
Alternatively you could put the error log file on a ramdisk.
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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