can someone explain IOSTAT ouput?
The following articles will give you a better idea about iostat. I always use iostat -x . http://mituzas.lt/2009/03/11/iostat/ http://www.igvita.com/2009/06/23/measuring-optimizing-io-performance/
The following articles will give you a better idea about iostat. I always use iostat -x . http://mituzas.lt/2009/03/11/iostat/ http://www.igvita.com/2009/06/23/measuring-optimizing-io-performance/
The best answer I can give you is “iowait is too high when it’s affecting performance.” Your “50% of the CPU’s time is spent in iowait” situation may be fine if you have lots of I/O and very little other work to do as long as the data is getting written out to disk “fast … Read more
You’re looking for iotop (assuming you’ve got kernel >2.6.20 and Python 2.5). Failing that, you’re looking into hooking into the filesystem. I recommend the former.
ls -l /dev/mapper/*, the device minor number (field 6 of what ls -l outputs) corresponds to the number in dm-\d+.