[mrtg] Re: MRTG performance under Linux

[Tobias Oetiker]

Today you sent me mail regarding MRTG performance under Linux:

*> Good day,
*> 
*> I solved the performance problem I had with MRTG and Linux.
*> 

cool ... 

will forward to the list ... 

cheers
tobi
*> You may want to hint at this in your FAQ.
*> 
*> By default, Redhat, Slackware and Debian (if not all versions)
*> install with the most conservative (slowest) hard drive parameters.
*> ie DMA is turned off and 16 bit transfer is used.
*> 
*> In my case the hard drive had a thru-put of 2M/sec and MRTG was
*> consuming 600k/sec (estimated).  In other words the machine was 
*> I/O bound considering the other tasks running.
*> 
*> If you'd like to include some help for this in your web pages;
*> here is how to check/change the hard drive setup.  this only
*> applies for IDE hard drives!
*> 
*> All examples are for the first hard drive; /dev/hda
*> 
*> hdparm -tT /dev/hda    [tests the speed of /dev/hda)
*> hdparm -v /dev/hda     [reads current settings]
*> hdparm -I /dev/hda     [queries hard drive for info]
*> 
*> hdparm -c1 /dev/hda [enables 32 bit transfer]
*> hdparm -d1 /dev/hda [enables DMA]
*> 
*> Warning: do not enable DMA before 32 bit xfer.
*> 
*> Ultra DMA mode can be enabled with
*> hdparm -X66 /dev/hda  [be very carefull with this!]
*> 
*> In my case my 6.5G and 13G hard drives are 4M/sec by default and
*> 14M/s after setting 32 bit Xfer and DMA on.
*> 
*> Thanks,
*> 
*>   - Eric Praetzel, University of Waterloo
*> 

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