I/O Monitoring

1. The main tool used is iostat.

   # Show in human readable
   # And extended information
   iostat --human -x
   
   # Example
   # check for particular devices 
   # refresh every 2 seconds
   # run for 200 times 
   iostat --human /dev/sda /dev/sdb 2 200

   if %util is close to 100%, the system is I/O-bound.

2. Also used is:

   iotop -o

   Which gives a list of processes that utilize the I/O. be stands for best effort, rt stands for real time in the prio column.

3. ionice we can schedule I/O and priority for processes.

   # -c arg:
   # 0 default 
   # 1 real-time 
   # 2 best-effort
   # 3 no access unless no other program askes for it
   
   # -n arg:
   # 0 highest priority
   
   # -p
   # pid
   ionice -c [0-4] -n [0-7]
   
   # Example
   ionice -c 2 -n 3 -p 30078

Load Testing Tools

We can use bonnie++, bon_csv2html and bon_csv2txt to benchmarking

time sudo bonnie++ -n 0 -u 0 -r 100 -f -b -d /mnt

Another option is fsmark.