VTAM Buffer Usage By Category Attributes
Use the VTAM 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.