HP OpenVMS Systems Documentation

The class prefix always follows the class header for component class records. It contains data describing the number of elements (for example, processes for the PROCESSES class, disks for the DISK class) represented by the class records for the current collection interval. Unlike system class records, which have one data block per record, component classes have one data block per element.

One of the class prefix data items describes the number of elements (and therefore the number of data blocks) included in the class record. The other class prefix data item is used only for the PROCESSES class, and describes the number of processes included in the interval. The following discussion applies only to the PROCESSES class.

It is possible to monitor a number of processes so large that the required number of data blocks for one collection interval does not fit into a single maximum size record. In this case, the required number of PROCESSES class records is created to fully describe the processes.

All class headers in the set of PROCESSES class records for a given interval are identical, except for the setting of bit 0 in the MNR_CLS$W_FLAGS field. This bit is set to 1 for all records except the last, for which it is set to 0.

The class prefixes in the set of class records vary, as described in the table following the next figure. The contents of the MNR_CMP$L_ELTCT field depends on the number of data blocks contained in the record; the contents of the MNR_CMP$L_PCTINT field remain constant for each record in the set. All records in the set except the last contain as many data blocks as will fit into the maximum size record (32000 bytes). The last record in the set contains the remaining data blocks.

Figure H-7 illustrates the class prefix format.

Figure H-7 Class Prefix Format

The following table describes the fields in the class prefix. The class prefix is 8 bytes long.

The size and format of each data block and the number of blocks per record depend on the class. System classes have one data block per record. Component classes have one data block per element. The fields within each block are performance data items.

The following sections describe the data items within the data block for each class. Every data item falls into one of three categories. It is either a count, a level, or an informational item. A count is a numeric quantity that increases at each succeeding interval for the duration of a system boot. A level is a numeric quantity that may increase or decrease at each succeeding interval. An informational item represents data that, rather than being a unit of performance measurement (as are the first two types), is descriptive in nature.

In the tables that follow, item types are identified by the letters C (count), L (level), and I (informational). Item types are shown in parentheses, following the length of the field. Class records are listed alphabetically.

H.4.2.1 CLUSTER Class Record

The CLUSTER class record contains data describing clusterwide CPU, memory, and locking activity. The CLUSTER class record has a record type of 19 and a size of 65 bytes. Note that when the CLUSTER class is recorded, the DISK and MODES classes are also recorded, even if not explicitly requested.

Figure H-8 illustrates the format of the CLUSTER class record.

Figure H-8 CLUSTER Class Record Format

The following table describes the fields in the data block for the CLUSTER class record:

The DECNET class record contains data describing the operation of the DECnet for OpenVMS subsystem. The DECNET class record has a record type of 8 and a size of 36 bytes.

Figure H-9 illustrates the format of the DECNET class record.

Figure H-9 DECNET Class Record Format

The following table describes the fields in the data block for the DECNET class record:

The DISK class record contains data describing all disk devices in the system. The DISK class record has a record type of 12; its size depends on the number of disks being monitored. The size, in bytes, is calculated by adding the size of the class header, the class prefix, and the data blocks contained in the record. This is shown in the following formula:

16 + 8 + (44 * the value of MNR_CMP$L_ELTCT) 

Figure H-10 illustrates the format of the DISK class record on Alpha and Integrity servers.

Figure H-10 DISK Class Record Format - Alpha and Integrity servers

The following table describes the fields in the data block for the DISK class record:

The DLOCK class record contains data describing the operation of the Distributed Lock Management facility. The DLOCK class record has a record type of 14 and a size of 76 bytes.

Figure H-11 illustrates the format of the DLOCK class record.

Figure H-11 DLOCK Class Record Format

The following table describes the fields in the data block for the DLOCK class record:

The FCP class record contains data describing the operation of the file system ACPs. The FCP class record has a record type of 5 and a size of 64 bytes.

Figure H-12 illustrates the format of the FCP class record.

Figure H-12 FCP Class Record Format

The following table describes the fields in the data block for the FCP class record:

The FILE_SYSTEM_CACHE class record contains data describing the operation of the caches for the file system ACPs and XQPs. The FILE_SYSTEM_CACHE class record has a record type of 11 and a size of 72 bytes.

Figure H-13 illustrates the format of the FILE_SYSTEM_CACHE class record.

Figure H-13 FILE_SYSTEM_CACHE Class Record Format

The following table describes the fields in the data block for the FILE_SYSTEM_CACHE class record:

The I/O class record contains data describing the operation of the I/O subsystem. The I/O class record has a record type of 4 and a size of 72 bytes.

Figure H-14 illustrates the format of the I/O class record.

Figure H-14 I/O Class Record Format

The following table describes the fields in the data block for the I/O class record: