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Tuning I/O resources

Subsystems that affect disk and other I/O

There are two methods of transferring data between memory and disk:

To make the transfer of data between memory and disk more efficient, the system maintains a buffer cache of most recently accessed disk data. This reduces the amount of disk I/O that the system needs to perform. See ``How the buffer cache works'' for a description of its operation.

In a similar way, the system maintains a namei cache (for translating names to inodes) of most recently used filenames in order to speed up locating files within filesystems. See ``How the namei cache works'' for a description of its operation.

Finally, the multiphysical buffers use a small pool of memory (generally 160KB to 256KB in size). They are used for various purposes as described in ``How multiphysical buffers are used''.

For a description of how to monitor the activity of block devices including disks, see ``Viewing disk and other block I/O activity''.

Disk I/O and networked filesystem (such as NFS®) performance are affected by filesystem fragmentation and other filesystem-related factors as described in ``Filesystem factors affecting disk performance''.


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SCO OpenServer Release 5.0.7 -- 11 February 2003