VTAM Buffer Usage By Category Attributes
Use the Buffer Pool Usage By Category attributes
to monitor the usage of the IO00 buffer pool based on contents.
The IO00 buffer pool manages the storage of all network input/output messages
sent from application programs and across channel connections. All network
traffic passes through this pool, regardless of its destination. This buffer
pool also contains channel programs used to service locally attached devices.
Because a great deal of activity takes place in the IO00 buffer pool, it
is very sensitive to dynamic fluctuations in traffic rates. Consequently,
it is a prime candidate for tuning. Examining the contents of this buffer
pool can help a network capacity planner plan for more common storage area
(CSA), understand how applications are using the pool, and understand the
network traffic activity.
The values reported in this attribute table are obtained by processing
the contents of the buffers themselves, and the VTAM control blocks are examined
to determine which of the two categories each of the buffers in the IO00 pool
is to be associated with.
Buffer Pool Category
The VTAM IO00 buffer pool usage category.
Valid responses are User Category or User Category 2 . Use the information below to determine the types of
buffers in each user category:
- User Category: Each buffer in the IO00 buffer pool
is examined to determine if it falls into each of the following areas.
- Unallocated buffers
- Read channel program buffers
- Buffers with a Transmission Subsystem Control Block (TSCB)
- Miscellaneous category consisting of buffers that do not meet any of the
criteria of the previously listed categories
The relative percentage of buffers for each of these categories is calculated
and displayed.
- User Category 2: Each buffer in the IO00 Buffer
Pool which contains a TSCB is examined to determine if it falls into each
of the following areas.
- SSCP traffic
- Virtual route pacing response traffic
- APPL(PLU) to same subarea resource traffic
- APPL(PLU) to a different subarea resource traffic
- APPL(SLU) to a different subarea resource traffic
- Local SNA resource to a different subarea APPL traffic
- Local non-SNA to a different subarea
- Intermediate routing node traffic
The relative percentage of buffers for each of these categories is calculated
and displayed.
Buffer Pool Name
The name of the VTAM buffer pool. This
value is always IO00 in this attribute group.
Collection Time
The time and date of the data sampling.
This time is displayed in the following format:
mm/dd/yy hh:mm:ss
Where:
- mm = Month
- dd = Day of the month
- yy = Year
- hh = Hour
- mm = Minute
- ss = Seconds
The stored format is a string no longer than 16 characters in the format CYYMMDDHHMMSSmmm (as in 1020315064501000 for 03/15/02 06:45:01) where:
- C = Century (0 for 20th, 1 for 21st)
- Y = Year
- M = Month
- D = Day
- H = Hour
- M = Minute
- S = Second
- m = Millisecond
Description
The description of the buffer based on the contents of the
buffer. The format is an alphanumeric string no longer than 40 characters.
This field can have the following values:
- APPL (PLU) to Different Subarea Resource: I/O buffers
being used for traffic flowing between a primary logical unit (PLU) application
and a secondary logical unit (SLU) source in another subarea.
- APPL (PLU) to Same Subarea Resource: I/O buffers
being used for traffic flowing between a primary logical unit (PLU) application
and a secondary logical unit (SLU) resource (both in this host).
- APPL (SLU) to Different Subarea Resource: I/O buffers
being used for traffic flowing between a secondary logical unit (SLU) application
on this host and a primary logical unit (PLU) application in another subarea.
- Intermediate Routing Node Traffic: I/O buffers being
used for traffic flowing between two resources, neither of which is in this
subarea
- Local Non-SNA to Different Subarea APPL: I/O buffers
being used for traffic flowing between a local non-SNA terminal and an application
in another subarea.
- Local SNA to Different Subarea APPL: I/O buffers
being used for traffic flowing between a local SNA terminal and an application
in another subarea.
- Misc: I/O buffers that could not be categorized.
This number includes path information units (PIUs) that could not be classified
because of state changes in VTAM, as well as channel programs (other than
read).
- Read Channel Programs: I/O buffers being used to
hold read channel programs. VTAM uses read channel programs to transfer data
from the NCP or local cluster control units and perform a read channel operation.
A read channel program consists of a string of channel command words (CCWs),
each allocated at the beginning of an I/O buffer. VTAM transfers the data
in blocks, each the size of an I/O Buffer.
- SSCP Traffic: I/O buffers being used for traffic
to and from the System Services Control Point (SSCP). The SSCP provides resource
management and control for the network. This field does not include the virtual
route pacing response traffic.
- TSCBs: This is the total number of Transmission
Subsystem Control Blocks (TSCBs) in the IO00 buffer pool. Each TSCB contains
a Path Information Unit (PIU).
- Unallocated Buffers: Buffers currently unallocated
and available.
- Virtual Route Pacing Response Traffic: I/O buffers
being used for virtual route pacing responses (VRPRSs). A VRPRS flows in response
to a request to send another full window of path information units (PIUs).
If this value is high, the maximum window size might be too small. Or, there
might be a large number of virtual routes defined and active.
Origin Node
The unique identifier for the VTAM node being
displayed. The format is an alphanumeric string no longer than 32 characters.
Percent
Percentage of the described buffer (which is based on its content)
relative to the other buffers within its user category. The format is an integer.
System ID
The SMF system ID. The format is an alphanumeric string no
longer than 4 characters.