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Oracle Tips by Burleson Consulting
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What to look for in vmstat
output
As you can see, each dialect of vmstat reports different information
about the current status of the server. Despite these dialect
differences, there are only a small number of metrics that are
important for server monitoring. These metrics include:
* r (runqueue)?The runqueue value shows the number of tasks
executing and waiting for CPU resources. When this number exceeds
the number of CPUs on the server, a CPU bottleneck exists, and some
tasks are waiting for execution.
* pi (page in)?A page-in operation occurs when the server is
experiencing a shortage of RAM memory. While all virtual memory
server will page out to the swap disk, page-in operations show that
the server has exceeded the available RAM storage. Any nonzero value
for pi indicates excessive activity as RAM memory contents are read
in from the swap disk.
* us (user CPU)?This is the amount of CPU that is servicing user
tasks.
* sy (system CPU)?This is the percentage of CPU being used to
service system tasks.
* id (idle)?This is the percentage of CPU that is idle
* wa (wait—IBM-AIX only)?This shows the percentage of CPU that is
waiting on external operations such as disk I/O.
Note that all of the CPU metrics are expressed as percentages.
Hence, all of the CPU values (us + sy + id + wa) will always sum to
100.
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