Example Output

Output Description

The first portion of the display describes reads and writes.

Reads and writes are tabulated in three categories: from disk, from buffers, and number of pages (read or written).

The first %cached field is a measure of the number of reads from buffers compared to reads from disk. The second %cached field is a measure of the number of writes to buffers compared to writes to disk.

The database server buffers information and writes to the disk in pages. For this reason, the number of disk writes displayed as dskwrits is usually less than the number of writes that an individual user executes:

dskreads

Is the number of actual reads from disk

pagreads

Is the number of pages read

bufreads

Is the number of reads from shared memory

%cached

Is the percent of reads cached, calculated as follows:

100 * (bufreads - dskreads) / bufreads 

If bufreads exceeds the maximum integer (or long) value, its internal representation becomes a negative number, but the value appears as 0.0.

dskwrits

Is the actual number of physical writes to disk

This number includes the writes for the physical and logical logs reported in onstat -l.

pagwrits

Is the number of pages written

bufwrits

Is the number of writes to shared memory

%cached

Is the percent of writes cached, calculated as follows:

100 *(bufwrits - dskwrits) / bufwrits 

If dskwrits exceeds bufwrits, the value appears as 0.0.

The next portion of the -p display tabulates the number of times different ISAM calls were executed. The calls occur at the lowest level of operation and do not necessarily correspond one-to-one with SQL statement execution. A single query might generate multiple ISAM calls. These statistics are gathered across the database server and cannot be used to monitor activity on a single database unless only one database is active or only one database exists:

isamtot

Is the total number of calls

open

Increments when a tblspace is opened

start

Increments the pointer within an index

read

Increments when the read function is called

write

Increments with each write call

rewrite

Increments when an update occurs

delete

Increments when a row is deleted

commit

Increments each time that an iscommit() call is made

No one-to-one correspondence exists between this value and the number of explicit COMMIT WORK statements that are executed.

rollbk

Increments when a transaction is rolled back

The next portion of the -p display provides information on generic pages. The Generic Page Manager provides an API for Dynamic Server to manage nonstandard pages in the database server buffer pool. The following table describes the Generic Page Manager fields in the onstat -p output.

gp_read

The number of generic page reads

gp_write

The number of generic page writes

gp_rewrt

The number of generic page updates

gp_del

The number of generic page deletes

gp_alloc

The number of generic page allocations

gp_free

The number of generic pages freed and returned to tblspaces

gp_curs

The number of cursors used against generic pages

The next portion of the -p display tracks the number of times that a resource was requested when none was available:

ovlock

Is the number of times that the database server attempted to allocate locks more than 15 times

For more information, see "LOCKS" on page 1-56.

ovuserthread

Is the number of times that a user attempted to exceed the maximum number of user threads

ovbuff

Is the number of times that the database server could not find a free shared-memory buffer

When no buffers are free, the database server writes a dirty buffer to disk and then tries to find a free buffer.

usercpu

Is the total user CPU time that all user threads use, expressed in seconds

This entry is updated every 15 seconds.

syscpu

Is the total system CPU time that all user threads use, expressed in seconds

This entry is updated every 15 seconds.

numckpts

Is the number of checkpoints since the boot time

flushes

Is the number of times that the buffer pool has been flushed to the disk

The next portion of the -p display contains miscellaneous information, as follows:

bufwaits

Increments each time that a user thread must wait for a buffer

lokwaits

Increments each time that a user thread must wait for a lock

lockreqs

Increments each time that a lock is requested

deadlks

Increments each time that a potential deadlock is detected and prevented

dltouts

Increments each time that the distributed deadlock time-out value is exceeded while a user thread is waiting for a lock

ckpwaits

Is the number of checkpoint waits

compress

Increments each time that a data page is compressed

seqscans

Increments for each sequential scan

The last portion of the -p display contains the following information:

ixda-RA

Is the count of read-aheads that go from index leaves to data pages

idx-RA

Is the count of read-aheads that traverse index leaves

da-RA

Is the count of data-path-only scans

RA-pgsused

Indicates the number of pages used that the database server read ahead

If this number is significantly less than the total number of pages read ahead, the read-ahead parameters might be set too high.

lchwaits

Stores the number of times that a thread was required to wait for a shared-memory latch

A large number of latch waits typically results from a high volume of processing activity in which the database server is logging most of the transactions.