SQL/MX 3.1 Installation and Management Guide (H06.23+, J06.12+)

Enhancing SQL/MX Database Performance
HP NonStop SQL/MX Release 3.1 Installation and Management Guide—663852-001
15-11
Using SCF STATS DISK to Monitor SQL/MX
Statistics and Reuse Failures
In Use................... 0 Failed FST....... 0
Failed ID........ 3

Max Data bytes identifies the configured size of the SQL/MX buffer for the disk.
In the given examples, the disk has been configured for 131072 KB, or 128 MB,
which is the default value.

Session Data bytes identifies the amount of virtual memory currently allocated
to SQL/MX buffer space for this DP2 process. The session data bytes can be
configured to be less than the
Max Data bytes. DP2 can increase Session
Data bytes to a higher value based on resource and other factors. This value
cannot exceed
Max Data bytes.

Total Sessions identifies the total number of sessions, including both active
and ended sessions.

Active Sessions identifies the number of SQL/MX sessions stored in the buffer
that are currently active.

MAX (under the heading 4KB Blocks) identifies the maximum number of 4 KB
blocks located in the SQL/MX buffer for the current value of
Max Data bytes. It
can also be interpreted as the maximum number of 4 KB blocks that will be located
in the SQL/MX buffer when the
Session Data bytes are equal to the Max
Data bytes.

Number (under the heading 4KB Blocks) identifies the number of 4 KB blocks
located in the SQL/MX buffer for the current value of
Session Data bytes.

In Use under 4KB Blocks identifies the number of 4 KB blocks in the buffer that
are currently in use or reusable.

Attempts under Reuse identifies the number of times an attempt has been made
to reuse plan fragments located in the SQL/MX buffer.

OK under Reuse identifies the number of times a successful attempt has been
made to reuse plan fragments located in the SQL/MX buffer.

Failed FST under Reuse identifies the number of plan fragments that are not
located in the free space table of the SQL/MX buffer and not available for reuse.
Failed ID under Reuse identifies the number of plan fragments that are present
in the free space tables but whose IDs reported that they could not be reused.
Together, Failed FST and Failed ID indicate the current number of unsuccessful
attempts that have been made to reuse plan fragments, whether missing or
unusable. For example, an unsuccessful attempt might result because one or more
4 KB blocks of the query fragment space has been stolen by another query. When
this happens, the missing query plan must be reloaded.
The
Failed FST and Failed ID fields provide the most important information about
reuse failures. You should monitor these values over a period of time, noting changes
and trends in the failure rates as different applications execute or when new resources
are added.