Displaying statistics for individual data sets processed by snapshot utilities
The Snapshot data set detail subpanel provides details about a data set processed by the snapshot utility.
To display the information for a specific data set, select a data set on the Snapshot data sets panel and press Enter.
Snapshot data set details on 03/28/2012 at 16:05:14
Data set : DSNDBZ.DSNDBD.XBMDBS6.TSS6S1.I0001.A001
Job name : XBMCPZAL Step name : BMCCOPY
Job date : 03/28/2008 Job time : 15:01:29
Restartable : NO XBM SSid : XOAJ
Cache limit . . : 0 KB Priority : 0
Bytes used . . . : 0 KB Used . . : 0 %
Compression . . : 0 % Compress : NO
Blocks in cache : 0 Hits . . : 0 %
Max bytes used : 0 KB Complete : 100 %
Reads Writes
Total . . . . . : 0 0
Failures . . . . : 0 0
Rate . . . . . . : 0 0
Status : STOPPED Return code : 0 Reason code : 0
F1=H F1=Help F4=Print F5=ExplnRsn F6=Detail F12=Cancel 2 0 %The following table describes the fields on the Snapshot data set details subpanel that provide statistics for the specified data set processed by the snapshot utility.
Field
Description
Data set
The fully qualified data set name
Job name
The name of the utility job that processed the data set
Step name
The name of the job step that ran the utility
Job date
The date that the utility registered this data set for snapshot processing
Job time
The time at which the utility registered this data set for snapshot processing
Restartable
Whether the snapshot utility is restartable for this data set and, if restartable, the current state of the data set
The following values can be displayed:
- NO—The snapshot for this data set is not restartable.
- YES, ACTIVE—The snapshot for this data set is still running but it is restartable should it fail.
- YES, PENDING—The snapshot for this data set has terminated due to a utility failure, and it can be restarted.
- YES, RESTARTED—The snapshot for this data set was restarted after a utility failure temporarily interrupted processing.
XBM SSid
The ID of the XBM subsystem upon which the snapshot-enabled utility is executing
Cache limit
The maximum amount of the extended buffer that will be allocated to this data set
The cache limit is defined on the Managed Object Information subpanel.
Priority
The priority of the managed object (a numerical value between 0 and 9999)
Bytes used
The actual number of bytes currently used in the extended buffer to cache the data set
Max bytes used
The maximum number of bytes used to cache pages for this object
Used %
The percentage of the cache limit that is currently being used to cache the data set
Compress %
The compression ratio for the data set
The compression percentage is calculated as the original number of bytes for a data set minus the number of bytes to cache the data set, divided by the original number of bytes, times 100. A high compression ratio value indicates compression is working effectively. A negative compression rate indicates that expansion is occurring.
Compression must be enabled for both the cache and the managed object for compression to be used.
Compress
Whether compression is enabled for the data set
Compression is also enabled or disabled for the different types of cache in the active configuration. For compression to take place, compression must be enabled for both the managed object and the cache.
Blocks in cache
The number of blocks in the extended buffer for this data set
Hits %
The percentage of read requests for the data set that were satisfied from the extended buffer or the extended prefetch buffer while the data set is actively managed
These hits are preimages of data pages that were cached in the extended buffer. The actual data page has been updated since the snapshot utilities data set was registered.
Complete %
The percentage of the of the data set for which the utility has completed snapshot processing
Total - Reads
The total number of blocks read for the data set by the utility job using the snapshot component
This value is the total number of read requests for the data set. Depending on the status of the data set, the number can include reads from the extended buffer, the extended prefetch buffer, or DASD, or both.
Failures - Reads
The number of times that the utility job processing the snapshot tried to read from the extended buffer and failed
In the case of a read failure, the utility requesting the snapshot is notified that the updated page was returned, because the preimage page was not available. The utility determines whether to continue or terminate.
Cache read failures occur when you are using an ESO hiperspace cache. (The system can steal pages from an ESO hiperspace cache.)
Rate - Read
The read access rate (in blocks per second) for the individual data set by the utility job that is processing the snapshot
Total - Writes
The number of writes to DASD by DB2 or VSAM for the data set
A write causes a preimage of the data page to be read into the extended buffer for the snapshot.
Failures - Writes
The number of times that an attempt to write to the cache failed
This problem occurs when the system cannot provide a new ESO hiperspace page when requested.
This statistic relates to the updates performed while the snapshot was running. These writes cause a preimage of the data page to be read into the extended buffer for snapshot processing. On a write failure the snapshot continues, but will receive a read failure if the preimage page is needed by the utility.
Rate - Writes
The number of blocks (measured in blocks per second) written to DASD by DB2 or VSAM for this data set
These writes might have caused preimages of data pages to be read into the extended buffer for the snapshot utilities.
Status
The status of a snapshot request
The following states can be displayed:
- REGISTERED—The snapshot-enabled utility coordinating the snapshot request has notified XBM of the data set name. XBM is initialized to start monitoring and caching updates to this data set.
- STARTED—The snapshot-enabled utility has issued the command to establish a point of consistency and has released the data set for update processing. XBM is caching pre-image data and providing these data blocks to the utility requesting the snapshot. A restartable snapshot request will continue to be in the STARTED status from start to finish. If the utility aborts, a restartable snapshot is still STARTED and caching pre-image data for use when the utility is restarted.
- STOPPED—Snapshot processing has completed. The cached data is released from the cache. The data set is no longer cached or monitored.
- TERMINATED—A restartable snapshot was aborted with the TERMINATE command in the XBM ISPF interface. The TERMINATE command frees the XBM cache blocks that were being held for the snapshot-enabled utility and eliminates the possibility of restarting the snapshot request for this data set.
Return code
The return code from the last snapshot request
For more information about codes issued by the snapshot component, access the messages section of the BMC Documentation Center from the BMC Support Central site (http://www.bmc.com/support).
Reason code
The reason code from the last snapshot request
For information about codes issued by the snapshot component, access the messages section of the BMC Documentation Center from the BMC Support Central site (http://www.bmc.com/support).