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z/OS File System Performance Tool
The File System Performance Tool (FPT),
an IBM internal tool,
consists of a POSIX application that
can simulate a variety of
environments
though
a selection of parameters to
access a set of database files
using several predefined read/write patterns and ratios.
FTP supports the following four file system activities.
- Block random (br)
To use this test mode, the user must specify the size
of the block. The minimum value of a block is 1 byte. The maximum value
can be the size of the file, however, this is not recommended because of
stability issues. Once the block size is established, a random file is
picked from the DB set, a random location is picked in that file and a
read or a write operation is performed (read or write is determined by a
random number generator with a read/write ratio provided by the user).
This is done for the entire duration of the test. At the beginning of
each iteration, all of the points in the DB set have an equal chance of
being selected.
- Block sequential (bs)
This test mode also requires the user to provide
the block size. All of the same rules apply as in the block random test
mode. Again, for stability reasons, it is not recommended to make the
block size equal to the file size. Once the block size is established, a
random file is picked from the DB set, a random location is picked in
that file (just like in block random). After that, all of the reads are
sequential. If an end of file is reached, the next file in the DB set is
opened. If the last file has been reached, the first DB file is opened.
At the beginning of the test all of the points in the DB set have an
equal chance of being selected.
- Character random (cr)
This test mode is identical to the block random
except the block size is predefined to be 1 byte.
- Character sequential (cs)
This test mode is identical to block
sequential except the block size is predefined to be 1 byte.
The following parameters are used to create specific measurement
environments.
- remove existing files? (yes or no)
- number of files to create (0 to 10,000)
- file size for created files (k=kB, m=mB, g=gB)
- number of paths (0 to number of files)
- number of processes (integer specifying the number of simulated
users)
- test mode (br=block random, bs=block sequential, cs=character
sequential,
cr=character random)
- block size (k=kB, m=mB)
- RW ratio (0 to 100)
- run length (s seconds, m minutes, h hours)
- warm-up time (seconds)
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