Version 7.4.3	SEARCH   INDEX   CONTENTS   |   PDF PAGE   PDF BOOKS   |   HOME   UP   PREV   NEXT

This document describes the Adabas Caching configuration parameters.

• Parameter Syntax

• Parameter Overview

• Parameter Descriptions

• ADACSH Session Parameter Examples

Parameter Syntax

The parameter input follows the standard Adabas ADARUN parameter conventions as follows:

• The format for specifying session parameters is: ADARUN { parameter=value } , ...

• ADARUN must be entered in positions 1-6 of each ADARUN statement.

• At least one blank is required between ADARUN and the first parameter.

• No blanks are permitted within a parameter=value entry.

• Multiple parameter=value entries separated by a comma may be included in a statement. The last trailing comma is ignored.

• A blank following a parameter=value entry indicates the end of the statement.

• All entries must end before position 73. A parameter=value entry that would extend beyond position 72 must be coded on a new statement.

• An asterisk (*) in position 1 indicates a user comment line.

The parameters are displayed on DDPRINT. If an error is detected during the processing of a statement, an error message is displayed and the remainder of the statement is ignored. Processing continues with the next statement. All parameters successfully processed are used to define the runtime settings. Defaults are used for the parameters that were not specified or were ignored due to errors.

Note:
If the ADACSH-related ADARUN parameters (for example, CASSODSP, CDATADSP...) are changed, the command I CMS must be issued before each Adabas nucleus is started in a VM/ESA environment.

Parameter Overview

An overview of the ADACSH parameters is provided in the table below.

Note:
The following parameters can only be used for global-level caching:

{CASSODSP | CASSOEXT | CASSOHSP | CASSOV64} {CDATADSP | CDATAEXT | CDATAHSP | CDATAV64} CSTORAGE

Note:
The following parameters can only be used for file-level caching:

CFILE and CXFILE.

Note:
Extended memory is the only option for RISC machines running BS2000. Hiperspace is an option only in OS/390 and z/OS environments. Virtual 64 storage is available only in z/OS environments.

The default value for each parameter is underlined.

Parameter Descriptions

• CACHE

• CACTIVATE

• CASSODSP / CASSOEXT / CASSOHSP / CASSOV64

• CASSOMAXS

• CBUFNO

• CCTIMEOUT

• CDATADSP / CDATAEXT / CDATAHSP / CDATAV64

• CDATAMAXS

• CDEMAND

• CDISPSTAT

• CEXCLUDE

• CFILE

• CMAXCSPS

• CRETRY

• CSTORAGE

• CWORKSTORAGE

• CWORK2FAC

• CWORK3FAC

• CXFILE

CACHE

CACHE (or CACH) specifies whether or not ADACSH is to be loaded during Adabas session initialization.

Example:

ADARUN CACHE=YES

ADACSH is loaded during the Adabas session initialization. ADACSH operator commands are accepted and caching is in effect.

CACTIVATE

CACTIVATE (or CACT) specifies whether or not all RABN ranges are to be activated at session open.

Example:

ADARUN CACTIVATE=YES

All RABN ranges are made available for immediate use; that is, as soon as the Adabas nucleus needs to move a block from the Adabas buffer pool into a RABN range, the RABN range is allocated.

CASSODSP / CASSOEXT / CASSOHSP / CASSOV64

Note:
CASSOxxx parameters are mutually exclusive with the CFILE and CXFILE parameters.

The CASSOxxx parameters identify one or more Associator RABNs to be cached where xxx indicates the type of cache space:

• CASSODSP (or CASSOD) for data space

• CASSOEXT (or CASSOE) for extended memory

• CASSOHSP (or CASSOH) for hiperspace

• CASSOV64 (or CASSOV) for virtual 64

Note:
Virtual 64 storage is only available in z/OS environments.

If CASSOxxx is specified, only the specified RABNs are cached. Unspecified RABNs are not cached and are subject to normal Adabas I/O operations.

Associator RABNs 1 through 30 are not cached; they are ignored if specified by the user.

Notes:

1. If an invalid RABN range is specified in the CASSOxxx parameter, subsequent RABN ranges for the CASSOxxx parameter are ignored. The ignored parameters can be added after initialization by using an operator command.
2. The CSTORAGE parameter overrides any CASSOxxx parameter and ADACSH will cache all Associator RABNs as defined for the database.

RABNs for the ranges specified are cached in the cache space indicated by the parameter suffix. RABN ranges defined with this parameter must therefore compete for the space available in a given cache space. When the maximum is allocated, RABNs are purged from the cache space based on a first-in-first-out (FIFO) mechanism and are reused to accommodate the latest RABNs being purged from the Adabas buffer pool.

Example:

ADARUN  CASSODSP=1330-2349,126-187,124-125,205-216
ADARUN  CASSOHSP=218-252,203-204,260-275,277-335

ADACSH caches the specified RABN ranges. No other Associator RABNs are cached.

The first four RABN ranges defined are cached in the Associator cache space allocated in data space (suffix DSP). The second four RABN ranges defined are cached in the Associator cache space allocated in hiperspace (suffix HSP).

CASSOMAXS

The CASSOMAXS (or CASSOM) parameter specifies the unit size in which areas are allocated for Associator cache space.

The total space available is equal to:

Maximum ASSO cache space size = CASSOMAXS · CMAXCSPS

Storage areas for a cache space are allocated when required. The Adabas nucleus informs ADACSH when a RABN is about to be purged from the buffer pool. If ADACSH determines that this RABN is being cached, it attempts to allocate space in the appropriate cache space.

When no space is available in the currently allocated areas for a cache space, or no areas are allocated, a new area of storage is allocated with the size specified by the CASSOMAXS parameter. For cache storage in

• extended memory, additional storage is requested in this area;

• data space, an additional data space is allocated;

• hiperspace, an additional hiperspace is built; and

• virtual 64 memory, an additional memory object is allocated.

This occurs until the maximum number of areas as determined by the CMAXCSPS parameter is reached. At this point, space is made for the latest RABNs to be purged from the Adabas buffer pool based on the aging algorithms.

The CASSOMAXS limit used for the allocation of new areas in a cache space is based on the last specification for this value. If no operator or Adabas Online System command is issued, this is the value specified in the start-up parameters. If this value is specified by an operator command or through Adabas Online System, it takes effect the next time an additional area is allocated in an ASSO cache space.

Example:

ADARUN CASSOMAXS=15000000

Cache space areas for ASSO RABNs are allocated in units of 15003648 bytes (or 14652K; or 14M).

CBUFNO

CBUFNO specifies the number of read-ahead buffers available for concurrent I/O processing.

CBUFNO is one of two parameters (CBUFNO and CEXCLUDE) used for read-ahead caching. Read-ahead caching performs a read-ahead of consecutive Associator and/or Data Storage blocks when processing serial Adabas commands (Read Logical, Read Physical, Histogram), and when searching using nondescriptors.

The read-ahead is performed by issuing a single EXCP to read all the consecutive Associator or Data Storage blocks that reside on a single track of the disk device. The blocks are kept in cache and are immediately available when the nucleus requests the next block in a sequence.

This feature may enhance performance by reducing the number of physical read I/Os. For example, for a 3380 Associator, a reduction factor of 18:1 may be achieved.

During normal cache processing, if a read I/O request qualifies for read-ahead processing but no read-ahead buffer is available, the read I/O is satisfied with a single block EXCP. In other words, no optimization is done to issue an EXCP to read the entire track.

Note:
Read-end-of-track processing is not available in Cluster and SMP environments.

Example:

ADARUN CBUFNO=5,CEXCLUDE=FIND/HIST

Five buffers are available for read-ahead caching. No read-ahead processing is performed for S1 (nondescriptor search) and L9 (histogram) commands.

CCTIMEOUT

The CCTIMEOUT (or CC) parameter specifies the amount of time (in seconds) a cache space area can remain inactive before it is released back to the system.

If demand caching (CDEMAND) is in effect, CCTIMEOUT specifies the number of seconds a RABN range, file, or file range can remain inactive before it is disabled.

If a cache space area has not been accessed for the specified period of time, ADACSH releases the storage associated with the area back to the operating system. A message is displayed on the operator console indicating that the cache space area was timed out. The cache space area can be re-allocated immediately by the caching system when required.

If a RABN range, file, or file range is not referenced for the specified period of time, and demand caching is in effect, the RABN range, file, or file range is disabled. A message is displayed on the operator console informing the user that the RABN range, file, or file range was timed out. No further caching occurs for that RABN range, file, or file range until the Adabas buffer efficiency goes below the level specified by CDEMAND. Once this occurs, the RABN range, file, or file range is enabled again and begins caching its associated RABNs.

Activity is checked at an interval of one half of the CCTIMEOUT value. For example, if CCTIMEOUT=3600 is specified, the allocated cache space areas, RABN ranges, files, or file ranges are checked every 1800 seconds (30 minutes).

A change to CCTIMEOUT using an operator command causes the check to be performed immediately, and subsequently at intervals of one half of the new CCTIMEOUT value.

Example:

ADARUN CCTIMEOUT=3600

A cache space area is released (or a RABN range/file/file range is disabled if demand caching is in effect) if there is no activity associated with it for a continuous period of 1 hour (3600 seconds).

CDATADSP / CDATAEXT / CDATAHSP / CDATAV64

Note:
CDATAxxx parameters are mutually exclusive with the CFILE and CXFILE parameters.

The CDATAxxx parameters identify one or more Data Storage RABNs to be cached where xxx indicates the type of cache space:

• CDATADSP (or CDATAD) for data space

• CDATAEXT (or CDATAE) for extended memory

• CDATAHSP (or CDATAH) for hiperspace

• CDATAV64 (or CDATAV) for virtual 64

Note:
Only extended memory is available for BS2000 RISC machines. Hiperspace is an option only in OS/390 or z/OS environments. Virtual 64 storage is available only in z/OS environments.

If CDATAxxx is specified, only the specified RABNs are cached. Unspecified RABNs are not cached and are subject to normal Adabas I/O operations.

Notes:

1. If an invalid RABN range is specified in the CDATAxxx parameters, subsequent RABN ranges for the CDATAxxx parameters will be ignored. The ignored parameters can be added after initialization by using an operator command.
2. The CSTORAGE parameter overrides any CDATAxxx parameter and ADACSH will cache all Data Storage RABNs as defined for the database.

RABNs for the ranges specified are cached in the cache space indicated by the parameter suffix. RABN ranges defined with this parameter must therefore compete for the space available in a given cache space. When the maximum is allocated, RABNs are purged from the cache space based on a first-in-first-out (FIFO) mechanism and are reused to accommodate the latest RABNs being purged from the Adabas buffer pool.

Example:

ADARUN  CDATADSP=1-4900,6523-7853 
ADARUN  CDATAHSP=5032-6204,8123-10382

ADACSH caches the specified RABN ranges. No other DATA RABNs are cached.

The first two RABN ranges defined are cached in the Data Storage cache space allocated in data space (suffix DSP). The second two RABN ranges defined are cached in the Data Storage cache space allocated in hiperspace (suffix HSP).

CDATAMAXS

The CDATAMAXS (or CDATAM) parameter specifies the unit size in which areas are allocated for Data Storage cache space.

The total space available is equal to:

Maximum DATA cache space size = CDATAMAXS · CMAXCSPS

Storage areas for a cache space are allocated when required. The Adabas nucleus informs ADACSH when a RABN is about to be purged from its buffer pool. If ADACSH determines that this RABN is being cached, it attempts to allocate space in the appropriate cache space.

When no space is available in the currently allocated areas for a cache space, or no areas are allocated, a new area of storage is allocated with the size specified by the CASSOMAXS parameter. For cache storage in

• extended memory, additional storage is requested in this area;

• data space, an additional data space is allocated;

• hiperspace, an additional hiperspace is built; and

• virtual 64 memory, an additional memory object is allocated.

This occurs until the maximum number of areas as determined by the CMAXCSPS parameter is reached. At this point, space is made for the latest RABNs to be purged from the Adabas buffer pool based on the aging algorithms.

The CDATAMAXS limit used for the allocation of new areas in a cache space is based on the last specification for this value. If no operator or Adabas Online System command is issued, this is the value specified in the start-up parameters. If this value is specified by an operator command or through Adabas Online System, it takes effect the next time an additional area is allocated in a Data Storage cache space.

Example:

ADARUN CDATAMAXS=15000000

Cache space areas for Data Storage RABNs are allocated in units of 15003648 bytes (or 14652K; or 14M).

CDEMAND

The CDEMAND (or CDE) parameter specifies the lowest Adabas buffer efficiency level accepted before caching is activated.

Calculated by the nucleus, Adabas buffer efficiency is the number of read requests divided by the actual number of reads to storage. If the Adabas buffer efficiency level drops below the specified CDEMAND level, ADACSH activates all disabled RABN ranges. In this way, RABN ranges are dynamically activated as demand on the Adabas buffer pool increases.

The CDEMAND parameter should be used in conjunction with the CCTIMEOUT parameter to establish resource usage boundaries that permit the timely acquisition and release of system resources. In other words, CDEMAND may be used to activate RABN ranges when the demand load on Adabas is high, and CCTIMEOUT may be used to deactivate RABN ranges when Adabas is idle.

If CDEMAND is not zero, the Adabas buffer efficiency is first checked approximately 30 minutes after the Adabas nucleus is initialized. Thereafter, the Adabas buffer efficiency is checked at intervals of approximately 15 minutes.

CDEMAND does not affect the activation of caching for Work parts 2 and 3 because these areas do not influence the Adabas buffer efficiency. Only Associator and Data Storage blocks reside in the Adabas buffer pool and, consequently, only the cache spaces for the Associator and Data Storage serve to increase the Adabas buffer efficiency level.

Example:

ADARUN CDEMAND=7

ADACSH activates the RABN ranges if the Adabas buffer efficiency level drops below 7.

CDISPSTAT

The CDISPSTAT (or CDI) parameter specifies whether the RABN range statistics are to be displayed on both the operator console and DDPRINT, or only on DDPRINT.

The individual RABN range statistics are displayed whenever a RABN range is released due to a parallel utility operation or an inactivity timeout, or when a RABN range is dynamically added or deleted.

Example:

ADARUN CDISPSTAT=NO

When the status of a RABN range is changed due to a parallel utility operation, a timeout, or an operator command to add or delete, the individual RABN range statistics are to be displayed on DDPRINT only.

CEXCLUDE

CEXCLUDE specifies the command types to be excluded from read-ahead caching.

CEXCLUDE is one of two parameters (CBUFNO and CEXCLUDE) used for read-ahead caching. Read-ahead caching performs a read-ahead of consecutive Associator and/or Data Storage blocks when processing serial Adabas commands (Read Logical, Read Physical, Histogram), and when searching using nondescriptors.

The read-ahead is performed by issuing a single EXCP to read all the consecutive Associator or Data Storage blocks that reside on a single track of the disk device. The blocks are kept in cache and are immediately available when the nucleus requests the next block in a sequence.

This feature may enhance performance by reducing the number of physical read I/Os. For example, for a 3380 Associator, a reduction factor of 18:1 may be achieved.

The exclusion list must be specified with each four-byte name separated by a slash ( / ). No intervening spaces or special characters, such as commas, are permitted.

The exclusion is made globally; for example, if CEXCLUDE=PHYS is specified, all L2 and L5 commands are excluded from read-ahead processing, regardless of the file to which the command was directed.

The exclusion list may be changed during the nucleus session using the CEXCLUDE and CINCLUDE operator commands.

Example:

ADARUN CBUFNO=5,CEXCLUDE=FIND/HIST

Five buffers are available for read-ahead caching. No read-ahead processing is performed for S1 (nondescriptor search) and L9 (histogram) commands.

CFILE

Note:
CFILE is mutually exclusive with the CASSOxxx, CDATAxxx, and CSTORAGE parameters. If any of these parameters is used with CFILE, they will be ignored.

The CFILE parameter defines a file or file range to be cached. It is also used to provide the settings used to control how caching is to be implemented for the file or file range.

Within the parentheses, the value terms are positional. This means that you can omit a term if you want to accept the default value for it, but you must enter a comma to identify the position if you are specifying a subsequent term within the parentheses.

Multiple CFILE parameters may be specified.

CFILE and CXFILE parameters together are processed in order from left to right (or top to bottom if different ADARUN statements are used). Parameters or statements that specify file ranges are processed before those that specify specific files.

Examples:

ADARUN CACHE=YES,CFILE=(7,2)

File-level caching is active for file number 7. The file is permitted to use up to 75% of the maximum total available cache space (class of service 2). Both Associator and Data Storage RABNS are cached (the default) and the type of cache space used is data space (the default).

ADARUN CACHE=YES,CFILE=(3-6,,DATA,HIPERSPACE)

File-level caching is active for file numbers 3 through 6. The files are permitted to use up to 50% of the maximum total available cache space (class of service 3, the default). Only Data Storage RABNS are cached, and the type of cache space used is hiperspace.

ADARUN CACHE=YES,CFILE=(14-17,,,HIPERSPACE)

File-level caching is active for file numbers 14 through 17. The files are permitted to use up to 50% of the maximum total available cache space (class of service 3, the default). Both Associator and Data Storage RABNs are cached (the default), and the type of cache space used is hiperspace.

CMAXCSPS

The CMAXCSPS (or CM) parameter specifies the number of storage areas that can be allocated for an ADACSH cache space in data spaces, hiperspaces, or memory objects (64-bit virtual storage). It has no effect on a cache space in extended memory, where only one Associator and one Data Storage area are allowed.

In conjunction with the CASSOMAXS and CDATAMAXS parameters, this parameter is used to control both the total amount of space that can be allocated for a cache space and the granularity with which it is allocated.

Example:

ADARUN CMAXCSPS=6

Up to six Associator cache space areas of size CASSOMAXS and up to six Data Storage cache space areas of size CDATAMAXS can be allocated for a particular type of cache space.

CRETRY

The CRETRY (or CR) parameter specifies the amount of time (in seconds) between attempts to acquire an area of cache space if the previous GETMAIN or space allocation failed.

If an area of cache space cannot be allocated, ADACSH waits for the specified number of seconds before attempting to allocate the area of cache space again. During this period of time, caching continues in the other areas of the cache space already allocated, but the maximum allowed cache space is not available. If, after the time period has elapsed, there is a request to cache a RABN and no space is available in the current allocation, ADACSH attempts to allocate the area of cache space again. These attempts continue until the cache space is successfully allocated.

Note:
CRETRY does not apply to an area of cache space that was released due to a timeout (see CCTIMEOUT).

Example:

ADARUN CRETRY=500

If an attempt to allocate an additional area of a cache space fails, another attempt to cache a RABN in the cache space in question is made after 500 seconds. If the currently allocated space is still full, the attempt is again made to allocate an additional area of cache space.

CSTORAGE

The CSTORAGE parameter can be used to indicate that all RABNs for the database are to be cached using the system defaults and the type of cache specified by this parameter.

The CSTORAGE (or CS) parameter overrides any CASSOxxx and/or CDATAxxx parameter that may be specified. If the CSTORAGE parameter is specified, all RABNs for the database are cached using the system defaults and the type of cache space specified by CSTORAGE.

Note:
This parameter is mutually exclusive with the CFILE and CXFILE parameters.

Extended memory is the only option available on BS2000 RISC machines. Hiperspace is an option only in OS/390 and z/OS environments. Virtual 64 storage is available only in z/OS environments.

Example:

ADARUN CASSOHSP=1-1795 
ADARUN CDATAHSP=81-135,1140-1298,136-170,181-230 
ADARUN CSTORAGE=EXTENDED

ADACSH caches all Associator and Data Storage RABNs in extended memory (above the 16 megabyte line). All CASSOHSP and CDATAHSP RABN ranges are ignored.

CWORKSTORAGE

The CWORKSTORAGE (or CWORKS) parameter specifies the type of cache space to use for the CWORK2FAC and/or CWORK3FAC areas.

Extended memory is the only option available on BS2000 RISC machines. Hiperspace is an option only in OS/390 and z/OS environments. Virtual 64 storage is available only in z/OS environments.

If CWORKSTORAGE is not specified, but the CWORK2FAC and/or CWORK3FAC parameters are specified, then the default CWORKSTORAGE is as follows:

• DATASPACE for BS2000 (except RISC machines), MVS/ESA, VSE/ESA, VM/ESA

• EXTENDED for BS2000 RISC machines

Example:

ADARUN CWORKSTORAGE=HIPERSPACE

For Work parts 2 and/or 3, cache space is allocated in hiperspace.

CWORK2FAC

The CWORK2FAC (or CWORK2) parameter specifies the percentage of Work part 2 to be cached.

The number of Work part 2 RABNs to be cached is computed by multiplying the specified percentage factor by the number of RABNs allocated for Work part 2.

Each cache space allocation is based on the number of RABNs and the device block size, rounded up to the nearest 4-kilobyte boundary.

cache size = int ( ( ( #RABNs · blksize ) + 4095 ) · 4096 ) + 4096

- where

#RABNs = int ( WORK part 2 size · CWORK2FAC )

If the specified CWORK2FAC cannot accommodate the working set of Work part 2 RABNs, the RABNs beyond the computed CWORK2FAC are not cached. Normal I/O operations are performed for the non-cached Work part 2 RABNs.

Example:

ADARUN CWORK2FAC=50

ADACSH caches 50 percent of Work part 2, beginning from the first block. If Work part 2 contains 1000 blocks, a cache space is allocated for 500 blocks. If the Work device type is a 3380, the cache space size required is

cache size = int ( ( ( #RABNs · blksize ) + 4095 ) ÷ 4096 ) · 4096 
               = int ( ( ( 500 · 5492 ) + 4095 ) ÷ 4096) · 4096 
               = 2,750,095

CWORK3FAC

The CWORK3FAC (or CWORK3) parameter specifies the percentage of Work part 3 to be cached.

The number of Work part 3 RABNs to be cached is computed by multiplying the specified percentage factor by the number of RABNs allocated for Work part 3.

Each cache space allocation is based on the number of RABNs and the device block size, rounded up to the nearest 4-kilobyte boundary.

cache size = int ( ( ( #RABNs · blksize ) + 4095 ) ÷ 4096 ) · 4096

- where

#RABNs = int ( WORK part 3 size · CWORK3FAC )

If the specified CWORK3FAC cannot accommodate the working set of Work part 3 RABNs, the RABNs beyond the computed CWORK3FAC are not cached. Normal I/O operations are performed for the non-cached Work part 3 RABNs.

Example:

ADARUN CWORK3FAC=50

ADACSH caches 50 percent of Work part 3, beginning from the first block of Work part 3. If Work part 3 contains 1000 blocks, a cache space is allocated for 500 blocks. If the Work device type is a 3380, the cache space size required is

cache size = int ( ( ( #RABNs · blksize ) + 4095 ) ÷ 4096 ) · 4096 
               = int ( ( ( 500  5492 ) + 4095 ) ÷ 4096 ) · 4096 
               = 2,750,095

CXFILE

The CXFILE parameter is used to exclude files from caching.

Note:
CXFILE is mutually exclusive with CASSOxxx, CDATAxxx, and CSTORAGE parameters. If any of these parameters is used with CXFILE, they will be ignored.

Multiple CXFILE parameters may be specified.

CFILE and CXFILE parameters together are processed in order from left to right (or top to bottom if different ADARUN statements are used).

Examples:

ADARUN CACHE=YES,CFILE=(13-19),CXFILE=(17)

Files 13 through 19 are cached using the standard defaults for class of service (3), scope (BOTH), and cache (DATASPACE) with the exception of file 17, which is not cached.

ADARUN CACHE=YES,CFILE=(13-19),CXFILE=(17),CXFILE=(16,,DATA)

Files 13 through 19 are cached using the standard defaults; however, file 17 is not cached and only the associated Associator RABNs are cached for file 16 since the Data Storage RABNs are excluded.

ADACSH Session Parameter Examples

The following combinations of ADARUN session parameters can be used as guidelines for setting up Adabas Caching. The applicability of these examples depends on the operating system environment and available resources.

Example 1:

 ADARUN CACHE=YES 

When CACHE=YES is the only parameter specified, the ADACSH module is loaded, but no cache spaces are predefined and no caching occurs.

ADACSH defaults to a global caching mode that allows RABN ranges to be added dynamically using operator or Adabas Online System commands. In this situation, any attempt to start caching on a file level is rejected.

Caching of Work parts 2 and 3 cannot be dynamically defined and is unavailable for this Adabas session.

Example 2:

  ADARUN CACHE=YES,CSTORAGE=HIPERSPACE,CACTIVATE=YES
    

Adding the CSTORAGE parameter instructs ADACSH to define cache spaces to encompass all of the Associator and Data Storage RABNs. The Adabas general control block (GCB) is used as the basis for the Associator and Data Storage RABN ranges. Although this is the most generalized parameter setup, an important consideration is the number of Associator and Data Storage RABNs that are defined for the database.

Using the CASSOMAXS, CDATAMAXS, and CMAXSPS parameters minimizes the total space allocated for the actual cache spaces. However, ADACSH must allocate space for RABN indexes for the cache space and for RABN tables for each RABN range being cached. If the database has a large number of RABNs defined, or the total amount of cache space available is very large, the memory requirements may exceed estimates. Therefore, this setup is not recommended for very large databases.

If the CACTIVATE=YES parameter is not specified, the cache spaces must be activated using Adabas Online System (AOS) or operator console communication.

Example 3:

ADARUN CACHE=YES,CDEMAND=30,CCTIMEOUT=3600

ADARUN CASSOHSP=1-5000,CDATAHSP=1-8000

No caching occurs for approximately 30 minutes after the nucleus has been brought up. After 30 minutes, if the nucleus requires caching and the Adabas buffer efficiency level is below the CDEMAND level, the RABN ranges are activated.

Following this, the first time space is required to cache a RABN, the first area of cache space is allocated. Once activated, a RABN range remains in operation as long as there is activity against it. Likewise, any allocated area of cache space remains allocated as long as there is activity against it.

If a RABN range remains inactive for more than 3600 seconds, it is disabled and is only re-activated if the Adabas buffer efficiency level is below the CDEMAND level. Areas of cache space represented by Hiperspaces are released back to the system if an area of cache space remains inactive for more than 3600 seconds. Unlike the RABN ranges, these are re-allocated immediately when required.

Example 4:

ADARUN CACHE=YES,CACTIVATE=YES,CDEMAND=30 

ADARUN CCTIMEOUT=7200 ADARUN CASSODSP=1-5000,CDATADSP=1-8000

The CACTIVATE=YES parameter specifies that the two data space RABN ranges are to be available for activation as soon as the nucleus requires caching. The CDEMAND parameter is not discarded but is initially superseded by the CACTIVATE parameter.

If a RABN range is inactive for more than 7200 seconds, it is disabled. When caching is required by the nucleus for RABNs within those RABN ranges which have been disabled, this will only occur once the CDEMAND level is reached. As long as the Adabas buffer efficiency level remains greater than the CDEMAND level, no disabled RABN ranges will be activated.

When an area of cache space represented by a data space is inactive for more than 7200 seconds, the data space is released. If this area is required at a later stage in the processing, it is re-activated as required and does not require that the Adabas buffer efficiency level fall below the value specified by CDEMAND.

Example 5:

ADARUN CACHE=YES,CACTIVATE=YES,CDEMAND=0

ADARUN CCTIMEOUT=7200 

ADARUN CASSOEXT=1-5000,CDATAEXT=1-8000 

ADARUN CWORKSTORAGE=DATASPACE,CWORK2FAC=50

ADARUN CWORK3FAC=70 

The CACTIVATE=YES parameter specifies that the two extended storage RABN ranges are to be available for activation as soon as the nucleus requires caching. The CDEMAND=0 parameter means that the RABN ranges are not disabled due to time out criteria; however, when areas of the cache space represented by the block of extended storage are not referenced for 7200 seconds, the block of storage is freed. It can be re-activated immediately when it is required by the nucleus.

Also, the first 50 percent of Work part 2 is cached in a data space cache and the first 70 percent of Work part 3 is cached in a second data space cache.

Example 6:

ADARUN CACHE=YES,CACTIVATE=YES ADARUN CCTIMEOUT=3600

ADARUN CFILE=3 ADARUN CFILE=1,2,ASSO,HIPERSPACE

ADARUN CFILE=200,1,BOTH,EXTENDED

The CACTIVATE=YES parameter specifies that caching for the files specified by the CFILE parameters can be activated as soon as the nucleus requires caching. If no reference is made to a cache space for more than 3600 seconds, it is released. If activity on the system increases and the cache space is again required, it is allocated immediately.

The first time each of the files 1, 3, and 200 are referenced, ADACSH synchronizes the file's RABN range definitions based on the file layout. The first time a RABN block being cached for one of these files is purged from the Adabas buffer pool, cache space is allocated and the RABN is written there first.

File number 3 is cached based on the defaults; that is, both Associator and Data Storage RABNs for the file are cached in data space and up to 50% of the cache space available for Associator or Data Storage RABN caching in data space may be used.

File number 1 has caching active only for Associator RABN blocks, which are cached in hiperspace. Up to 75% of the cache space available for Associator RABN caching in Hiperspace may be used.

File number 200 has caching active for both Associator and Data Storage RABN blocks, which are cached in extended memory. Up to 100% of the cache space available for Associator or Data Storage RABN caching in extended memory may be used.

Example 7:

ADARUN CACHE=YES,CFILE=(1-5,2),CXFILE=(2),CFILE=(2,1,DATA,HIPERSPACE)

CFILE and CXFILE parameters are processed in order from left to right (or top to bottom if different ADARUN statements are used). Parameters or statements that specify file ranges are processed before those that specify specific files.

Files 1 through 5 are cached with class of service 2 (use up to 75% of available cache space) and defaults for the other terms within the parentheses (scope BOTH and cache DATASPACE). File 2 is excluded; then it is added again with class of service 1 (use up to 100% of available cache space), caching Data Storage RABNs only, and caching in hiperspace.

To illustrate the order dependence of the CXFILE and CFILE parameters:

• If the CXFILE parameter is omitted in the above example, the result is the same.

• If the CXFILE parameter and the second CFILE parameter are reversed, file 2 is not cached.

www.softwareag.com

Copyright © Software AG 2009. All rights reserved.

SEARCH   INDEX   CONTENTS   |   PDF PAGE   PDF BOOKS   |   HOME   UP   PREV   NEXT