CHECK TABLESPACE options
CHECK TABLESPACE syntax diagrams
The following diagram illustrates CHECK TABLESPACE command syntax illustrates the syntax of the CHECK TABLESPACE command:
The following diagram provides syntax diagram details. Each detail diagram is numbered to correspond to a preceding section of the CHECK TABLESPACE syntax diagram or to another section of the detail.
CHECK TABLESPACE option descriptions
This section describes each CHECK TABLESPACE command option. The options are described in the order in which they appear in the CHECK TABLESPACE syntax diagram.
CHECK TABLESPACE
CHECK TABLESPACE checks the structural integrity of a space. You must specify the fully qualified name of the space that you want to check.
PART
The PART option specifies the partition number of the partitioned space that you want to check. You can specify one, some, or all of the partitions either individually or by specifying a range of partitions. If you do not specify PART, CHECK PLUS checks all partitions of the space.
Specifying partition numbers
Note the information about specifying partition numbers with the PART option:
- Individual partitions in a list can be in any order (but partitions within a range must be in ascending order).
- You can specify a mixture of individual partitions and ranges of partitions.
- If you specify a partition number more than once, CHECK PLUS ignores any occurrence after the first.
- You can specify integer values from 1 through 4096.
The following example illustrates a valid PART specification for parts 1 through 5, 7, and 10:
SHRLEVEL
The SHRLEVEL option specifies the level of access that concurrently operating Db2 applications and utilities have to the target spaces.
The following table describes the valid values for the SHRLEVEL option:
Value | Description |
|---|---|
REFERENCE | (Default) SHRLEVEL REFERENCE is the default and allows read-only access to the target spaces during check processing. |
CHANGE | SHRLEVEL CHANGE enables read/write access to the space. CHECK PLUS uses the snapshot-processing features of SUF (also known as XBM) to create a consistent image of the data, which CHECK PLUS uses for check processing. You must specify an appropriate SUF (also known as XBM) subsystem ID with the XBMID installation or command option (XBMID=). For more information about using the snapshot-processing features of SUF (also known as XBM) with CHECK PLUS, see SHRLEVEL CHANGE. |
ZIIP
The ZIIP option tells CHECK PLUS whether to attempt to use IBM System z Integrated Information Processors (zIIPs). CHECK PLUS can use enclave service request blocks (SRBs) to enable zIIP processing automatically while running jobs. Using zIIP processing can reduce the overall CPU time for CHECK PLUS jobs.
Specifying the default
You can specify the default for the ZIIP command option in your installation options module by using the ZIIP installation option (XBMID=). CHECK PLUS was shipped with a default value of ENABLED for this option. The ZIIP command option overrides the default that is in the installation options module.
The following table describes the valid values for the ZIIP option:
Value | Description |
|---|---|
ENABLED | CHECK PLUS attempts to offload eligible processing to an available zIIP. If the zIIP is busy or not available, normal processing continues on a general-purpose processor. To enable and use zIIP processing with CHECK PLUS, you must:
|
DISABLED | CHECK PLUS does not attempt to use zIIP processing. |
Using SUF (also known as XBM)
You can specify a particular SUF (also known as XBM) subsystem to use for zIIP processing by specifying a value for the XBMID installation or command option. For more information, see XBMID=.
SUF (also known as XBM) are licensed, installed, and maintained separately from CHECK PLUS. You can use either SUF (also known as XBM), depending on the license that you have obtained:
- License for the full version of the SUF (also known as XBM) product authorizes you to use all features of SUF (also known as XBM).
- License for SUF (also known as XBM) authorizes you to use only the snapshot and zIIP processing features of SUF (also known as XBM).
For more information about SUF (also known as XBM), see the SNAPSHOT UPGRADE FEATURE for DB2 documentation.
XBMID
Specify XBMID to identify the appropriate active SUF (also known as XBM) subsystem when you use either SUF (also known as XBM) with CHECK PLUS. You must specify an SUF (also known as XBM) subsystem in either of the following cases:
- You are specifying SHRLEVEL CHANGE (which uses the snapshot-processing functionality of SUF (also known as XBM).
- You want to use a specific SUF (also known as XBM) subsystem for zIIP processing.
The variable ssid (subsystem ID) is the unique identifier that you specified when you installed SUF (also known as XBM). If you are using SUF (also known as XBM) in a Db2 data sharing environment, you can use the value of the XBMGROUP parameter in place of ssid. The XBMGROUP is the name of the cross-system coupling facility (XCF) group that is defined to the SUF (also known as XBM) subsystem, and its default value is XBMGROUP.
For more information about using the snapshot-processing feature of SUF (also known as XBM) with CHECK PLUS, see SHRLEVEL CHANGE For detailed information about SUF (also known as XBM), see the SNAPSHOT UPGRADE FEATURE for DB2 documentation.
zIIP processing
If you specify an SUF (also known as XBM) subsystem and ZIIP ENABLED is in effect, CHECK PLUS attempts to use that subsystem to enable zIIP processing. If that subsystem is not available or not at the correct maintenance level, zIIP processing is not enabled.
If you do not specify an SUF (also known as XBM) subsystem (either here or with the XBMID installation option), CHECK PLUS searches for an SUF (also known as XBM) subsystem at the appropriate maintenance level to enable zIIP processing.
Specifying the default
You can specify the default for the XBMID command option in your installation options module by using the XBMID installation option (XBMID=). If the XBMID is not assigned in the installation option, you must specify this command option if you specify SHRLEVEL CHANGE.
WTOMSG
The WTOMSG command option is applicable only when running SHRLEVEL CHANGE.
Specify WTOMSG SUFSTART to write message BMC50008I to the IBM MVS system log to indicate that snapshot-processing initialization for CHECK PLUS has successfully completed. You can use the text of this message to trigger the submission of jobs that you want to run concurrently with the CHECK PLUS job.
Specify a text string of up to 50 characters enclosed in single quotes to indicate the message that you want CHECK PLUS to print in the MVS system log. CHECK PLUS truncates strings that are greater than 50 characters. Quotation marks cannot appear within the text string.
CHECKTSLEVEL
The CHECKTSLEVEL option specifies which checks CHECK PLUS performs on the named space. For detailed information about specific fields and values checked for each CHECKTSLEVEL, see Fields-and-values-checked-in-tables-and-indexes.
Value | Description |
|---|---|
1 | (Default) CHECKTSLEVEL 1 performs primarily intrapage checks on header pages, space map pages, and data pages in the space. |
2 | CHECKTSLEVEL 2 performs all CHECKTSLEVEL 1 checks plus additional interpage checks on such items as overflow pointers and records, valid rows incorrect partitions, and intact segment chains. It also validates column data if you specify the VERIFY option or if check constraints exist. |
RULES
The RULES command option is applicable only if you specify CHECKTSLEVEL 2.
The RULES option allows you to specify user-defined column condition rules.
Value | Description |
|---|---|
FOR TABLE | FOR TABLE indicates the table to which the the user-defined column condition rules apply. Restriction CHECK PLUS does not support Unicode names. |
VERIFY | Verify specifies the column condition that you want CHECK PLUS to check or verify. CHECK PLUS verifies that values in specified columns are within the domain that the condition criteria establish. See VERIFY for a detailed description of the VERIFY option. To validate Unicode data using CHECK PLUS, you must specify character constants as hexadecimal constants. |
VERIFYONLY
The VERIFYONLY command option is applicable only if you specify VERIFY or if check constraints exist.
This option allows you to check column-level conditions ( check constraints or rules specified with the RULES option) without page checking. See VERIFY for a detailed description of the VERIFY option.
EXCEPTIONS
The EXCEPTIONS option tells CHECK PLUS to terminate processing when the specified number of constraint violations is exceeded. The default value of 0 indicates that there is no limit on the number of errors. CHECK PLUS applies duplicate errors to this count.
MAXTASKS
The MAXTASKS option specifies the maximum number of sort tasks that CHECK PLUS can run concurrently. Like other BMC Software utilities for Db2, CHECK PLUS optimizes elapsed time by using all available resources. However, if you need to provide greater control over allocated resources, the MAXTASKS option allows you to restrict the number of concurrent tasks.
Specifying the default
You can specify the default for the MAXTASKS command option in your installation options module by using the SMAX installation option (SMAX=16). CHECK PLUS was shipped with a default value of 16 for this option; however, the value might have been changed during installation. The command option overrides the default that is in the installation options module.
DRAIN_WAIT
The DRAIN_WAIT option specifies the drain timeout value that you want CHECK PLUS to use.
Specifying the default
You can specify the default for the DRAIN_WAIT command option in your installation options module by using the DRNWAIT installation option (DRNWAIT). CHECK PLUS was shipped with a default value of NONE for this option; however, the value might have been changed during installation. The command option overrides the default that is in the installation options module.
The following table describes the valid values for the DRAIN_WAIT option:
Value | Description |
|---|---|
NONE | If you specify NONE, the drain request issued by CHECK PLUS times out immediately if the drain cannot acquire the lock. NONE prevents any application transactions from being queued during the drain process. We recommend that you specify NONE in high-transaction environments, such as SAP. |
UTIL | UTIL tells CHECK PLUS to use the standard Db2 utility timeout value defined in DSNZPARMS for your site (IRLMRWT multiplied by UTIMOUT). The wait time applies to each object involved in the check. |
SQL | If you specify SQL, CHECK PLUS uses the standard SQL timeout value (IRLMRWT) as the drain timeout value. The wait time applies to each object involved in the check. If it cannot drain all of the objects within the time period specified by DRAIN_WAIT, CHECK PLUS releases the drains it has obtained so far, waits the time that you specified in RETRY_DELAY, and tries to drain the objects again for the number of times that you specified in RETRY. |
RETRY
The RETRY option specifies the maximum number of times that CHECK PLUS attempts to obtain a drain before the job terminates. The number of attempts can range from 0 through 255.
Specifying the default
You can specify the default for the RETRY command option in your installation options module by using the DRNRETRY installation option (DRNRETRY). CHECK PLUS was shipped with a default value of 255 for this option; however, the value might have been changed during installation. The command option overrides the default that is in the installation options module.
RETRY_DELAY
After a drain time out, the RETRY_DELAY option specifies the minimum number of seconds that CHECK PLUS waits before it tries again to obtain the drain. The number of seconds can range from 1 through 1800.
Specifying the default
You can specify the default for the RETRY_DELAY command option in your installation options module by using the DRNDELAY installation option (DRNDELAY). CHECK PLUS was shipped with a default value of 1 for this option; however, the value might have been changed during installation. The command option overrides the default that is in the installation options module.
DSPLOCKS
The DSPLOCKS option tells CHECK PLUS what action to take regarding displaying claims and locks if a drain attempt times out.
Specifying the default
You can specify the default for the DSPLOCKS command option in your installation options module by using the DSPLOCKS installation option. CHECK PLUS was shipped with a default value of DRNFAIL for this option; however, the value might have been changed during installation. The command option overrides the default that is in the installation options module.
The following table describes the valid values for the DSPLOCKS option:
Value | Description |
|---|---|
DRNFAIL | If you specify DRNFAIL, CHECK PLUS displays the claims and locks once, after the final attempt to obtain the drain times out. |
NONE | If you specify NONE, CHECK PLUS does not display any claims or locks. |
RETRY | If you specify RETRY, CHECK PLUS displays claims and locks after each drain timeout. |