The algorithm for iowait used to be something like: if idle and vmstat b nonzero then iowait So on Solaris 10, vmstat b is gone as well as iowait. If you want to see how much time you are waiting for io, use iostat and add up the times for each disk.
Here is one way it was broken, a cpu starts an io, a different cpu completes the io, which cpu was waiting? Adrian On 10/18/06, Mike Gerdts <[EMAIL PROTECTED]> wrote:
On 10/18/06, adrian cockcroft <[EMAIL PROTECTED]> wrote: > In Solaris 10, iowait is no longer measured and will be reported as > zero by existing tools. Since iowait was always a variant of idle > time, this makes no difference to usr or sys time. > iowait was always a confusing and useless metric, which is why it was removed. On a related note, I have yet to see vmstat's "b" (kernel threads blocked on I/O) column be non-zero. This includes a large RAC environment where the previous measure of I/O health was (don't shoot the messenger!) iowait. The same workload on S9 consistently showed non-zero values in the "b" column. Has the meaning of this value changed as well, or is Solaris 10 just that much better at getting I/O out of the queue? TIA, Mike -- Mike Gerdts http://mgerdts.blogspot.com/
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