Monday, February 14, 2011

Solaris VMSTAT

A.   CPU issues:
Following columns has to be watched to determine if there is any cpu issue
  1. Processes in the run queue (procs r)
  2. User time (cpu us)
  3. System time (cpu sy)
  4. Idle time (cpu id)
5.     Problem symptoms:
6.    
1.)   If the number of processes in run queue (procs r) are consistently greater than the number of CPUs on the system it will slow down system as there are more processes then available CPUs .
2.)    if  this number is more than four times the number of available CPUs in the system then system is facing shortage of cpu power and will greatly slow down the processess on the system.
3.)    If  the idle time (cpu id) is consistently 0 and if the system time (cpu sy) is double the user time (cpu us)  system is facing shortage of CPU resources.
 
Resolution :
         Resolution to these kind of issues involves tuning of application procedures  to make efficient use of cpu  and as a last resort increasing the cpu power or adding more cpu to the system.

B.   Memory Issues:
Memory bottlenecks are determined by the scan rate (sr) . The scan rate is the pages scanned by the clock algorithm per second. If the scan rate (sr) is continuously over 200 pages per second then there is a memory shortage.

Resolution :
1. Tune the applications & servers to make  efficient use of memory and cache.
2. Increase system memory .
3. Implement priority paging in s in pre solaris 8 versions by adding line "set priority paging=1" in /etc/system. Remove this line if upgrading from Solaris 7 to 8 & retaining old /etc/system file