IFCID 201 - Alter Buffer Pool
This topic shows detailed information about Record Trace - IFCID 201 - Alter Buffer Pool
.
This IFCID records the status of a buffer pool before and after an ALTER BUFFERPOOL command.
Record trace - IFCID 201 - Alter Buffer Pool
The field labels shown in the following sample layout of Record Trace - IFCID 201 - Alter Buffer Pool
are described in the following section.
BUFFERPOOL ID: 25 NAME: BP25 ALTER COMMAND: ALTER RETURN CODE: 0 REASON CODE: 0
OLD STATUS NEW STATUS
---------------------- ----------------------
VPOOL SIZE : 0 VPOOL SIZE : 10
VPOOL SEQ THRESH : 80 VPOOL SEQ THRESH : 80
VPOOL DWT THRESH : 30 VPOOL DWT THRESH : 30
VPOOL VDWT THRESH VPOOL VDWT THRESH
PERCENTAGE : 5 PERCENTAGE : 5
BUFFERS : 0 BUFFERS : 0
VPOOL PLL SEQ THRESH : 50 VPOOL PLL SEQ THRESH : 50
ASSISTAN. SEQ THRESH : 0 ASSISTAN. SEQ THRESH : 0
PAGE STEAL METHOD : LRU PAGE STEAL METHOD : LRU
AUTOSIZE : NO AUTOSIZE : NO
FRAMESIZE : 4K FRAMESIZE : 4K
VPOOL SIZE MIN : 0 VPOOL SIZE MIN : 0
VPOOL SIZE MAX : 0 VPOOL SIZE MAX : 0
SIM POOL SIZE : 200 SIM POOL SIZE : 300
SIM POOL SEQ THRESH : 50 SIM POOL SEQ THRESH : 75
- BUFFERPOOL ID
-
The buffer pool internal identifier. The values 0 through 49 are the identifiers for BP0 through BP49. The values 80 through 89 are the identifiers for BP32K through BP32K9.
Field Name: QW0201BP
- NAME
-
Buffer pool name.
Field Name: QDBPNM
- ALTER COMMAND
-
This field indicates how the buffer pool was altered. Possible values:
- ALTER
- The ALTER BUFFERPOOL command was used.
- AUTOSIZE
- The AUTOMATIC AUTOSIZING (AUTOSIZE(YES) option on ALTER BUFFERPOOL was previously specified.
Field Name: QW0201CD
- RETURN CODE
-
The return code for the ALTER BUFFERPOOL command.
Field Name: QW0201RT
- REASON CODE
-
The reason code returned from an unsuccessful ALTER BUFFERPOOL command.
Field Name: QW0201RE
- VPOOL SIZE (OLD)
-
The size of the old virtual pool.
Field Name: QW0201OP
- VPOOL SIZE (NEW)
-
The size of the new virtual buffer pool.
Field Name: QW0201NP
- VPOOL SEQ THRESH
-
The old and new virtual pool sequential steal threshold.
Old status taken from the Db2 field QW0201OT.
New status taken from the Db2 field QW0201NT.
Field Name: RT0201VS
- VPOOL DWT THRESH
-
The old and new virtual pool deferred write threshold (DWT).
Old status taken from the Db2 field QW0201OD.
New status taken from the Db2 field QW0201ND.
Field Name: RT0201VD
- VPOOL VDWT THRESH - PERCENTAGE
-
The vertical deferred write threshold for the virtual buffer pool expressed as percentage.
Old status taken from the Db2 field QW0201OV.
New status taken from the Db2 field QW0201NV.
Field Name: RT0201PC
- VPOOL VDWT THRESH - BUFFERS
-
The vertical deferred write threshold for the virtual buffer pool expressed as an absolute number of buffers. It is only used if VERTICAL DEFERRED WRITE THRESHOLD (PERCENTAGE) is 0.
Old status taken from the Db2 field QW0201OJ.
New status taken from the Db2 field QW0201NJ.
Field Name: RT0201BU
- VPOOL PLL SEQ THRESH
-
The old and new virtual pool parallel sequential threshold.
Old status taken from the Db2 field QW0201OQ.
New status taken from the Db2 field QW0201NQ.
Field Name: RT0201VP
- ASSISTAN. SEQ THRESH
-
The assisting parallel sequential threshold before and after the ALTER BUFFERPOOL command was issued.
Old status taken from the Db2 field QW0201OX.
New status taken from the Db2 field QW0201NX.
Field Name: RT0201AS
- PAGE STEAL METHOD
-
Identifies the page stealing algorithm (PGSTEAL) that is used for the virtual buffer pool. It controls when and whether performance-critical objects in buffer pools are removed from buffer pools when the space is needed by other objects. Possible values are:
- LRU
- Least recently used (LRU) objects are removed first. This means it takes away pages that are not used so that more recently used pages can remain in the virtual buffer pool. This is used by default.
- FIFO
- First-In-First-Out (FIFO) means that the oldest objects are removed first. This results in a small decrease in the cost of a Getpage operation. It can reduce internal Db2 latch contention in environments that require very high concurrency.
- NONE
- Objects are not removed from buffer pool (no page stealing). This setting provides the highest availability for business-critical objects.
Old status taken from the Db2 field QW0201OK.
New status taken from the Db2 field QW0201NK.
Field Name: RT0201PS
- AUTOSIZE
-
The old and new status of the AUTOSIZE attribute.
Old status taken from the Db2 field QW0201OZ.
New status taken from the Db2 field QW0201NZ.
Field Name: RT0201AT
- FRAMESIZE (OLD)
-
The size of the old frame (4 KB,1 MB, or 2 GB).
Field Name: QW0201OC
- FRAMESIZE (NEW)
-
The new frame size (4 KB, 1MB, or 2GB).
Field Name: QW0201NC
- VPOOL SIZE MIN (OLD)
-
The minimum size of the old virtual pool.
Field Name: QW0201OA
- VPOOL SIZE MIN (NEW)
-
The minimum size of the new virtual pool.
Field Name: QW0201NA
- VPOOL SIZE MAX (OLD)
-
The maximum size of the old virtual pool.
Field Name: QW0201OB
- VPOOL SIZE MAX (NEW)
-
The maximum size of the new virtual pool.
Field Name: QW0201NB
- SIM POOL SIZE (OLD)
-
The old number of simulated buffers specified for the simulated buffer pool.
Field Name: QW0201OS
- SIM POOL SIZE (NEW)
-
The new number of simulated buffers specified for the simulated buffer pool.
Field Name: QW0201NS
- SIM POOL SEQ THRESH (OLD)
-
The old sequential steal threshold for the simulated buffer pool, expressed as a percentage of the total simulated buffer pool size.
Field Name: QW0201OH
- SIM POOL SEQ THRESH (NEW)
-
The new sequential steal threshold for the simulated buffer pool, expressed as a percentage of the total simulated buffer pool size.
Field Name: QW0201NH