To estimate the impact that
from filesystems has on disk activity, multiply the
pgfil/s reported by sar -p
(or mpsar -p for SMP) by 8 to convert
from 4KB pages to the number of 512-byte disk blocks read
or written per second:
Disk activity due to paging in = 8
The amount of disk activity caused by swapping and paging out
to the swap areas can be estimated
from the values of
reported by sar -w (or mpsar -w
Disk activity due to swapping = 8 (
These values can be compared with
the total number number of blocks per second being transferred
to and from the disks containing the filesystems and swap areas.
Use sar -d (or mpsar -p for SMP)
to report the number of blocks transferred per second
``Viewing disk and other block I/O activity''
for more information about monitoring hard disk activity.
If a high proportion of disk activity is caused by paging in, and this is causing a disk bottleneck, see ``Tuning disk I/O-bound systems'' for suggested ways to cure this.
If swapping and paging out is causing a disk bottleneck,
you could create swap areas on several
disks to relieve the load on a single disk.
However, it is far better
to reduce the memory shortage.