Vmstat
Columns Information
(r,b) - How many process can be run if a CPU is available and how many are blocked.
(swpd, free, buff, cache) - Show how memory space is used.
(si, so) - Page-In and Page-Out
(io, bi, bo) - Number of Blocks received and sent to block devices
(in, cs) - Number of Interupts and context switches
(us, sy, id, wa) - Indicate percentage of time the CPU(s) has spent in userspace applications, in the kernel, being idle....
# vmstat 5 10 (To run vmstat with ten updates, five seconds )
Articles to consider:
- Monitoring Virtual Memory with vmstat by LINUX Journal
- Understanding the Linux Virtual Memory Manager by Mel Gorman
- Is swap space obsolete? by Martin Pool
Disk Performance
Hdparm is a good tool to determine whether the disks are healthy and configured
# hdparm -tT /dev/sda
Article to consider:
- Speeding up Linux Using hdparm by O'Reilly
# iostat -x sda 1
(%iowait) - High means CPU is idele and waiting for outstanding disk I/O requests.
(avgqu-sz) - Value should be less than 1
(%util) - pecentage of time the disk has requests.
To install on CentOS, Fedora, "yum install sysstat", iostat will be installed with the packages.
Articles to consider:
