These statistics are collected from OpenVMS performance statistics for each node in a cluster that was present during the reporting interval. Each line of statistics gives the name of the node that is sending data to, or receiving data from, the local node. There are three types of messages:
Datagrams are used primarily by DECnet, the CI, and by the HSC for error logging. The delivery and order of messages is not guaranteed.
For block transfer mode, if I/Os are targeted to disks on an HSC, the Kbytes mapped by the local node are recorded, but not the transfer counts, nor the Kbytes transferred. This is because the HSC actually initiates the block mode transfer.
If I/Os are targeted to disks hosted on an OpenVMS node (MSCP server), the hosting OpenVMS node shows the transfer counts, and Kbytes mapped as I/O that it initiated to satisfy requests for data made by a remote node. This is the only time numbers for transfer counts and Kbytes transferred are reported. The initiator of the transfer is not the node that issues the initial QIO but the node that issues the SCS directive for block mode transfer services to satisfy the I/O request.
Sequenced messages are used by the Distributed Lock and Connection Managers, also implicitly in disk I/O to set up block mode transfers. For sequenced messages SCS imposes its own flow control, and delivery and order of messages is guaranteed.
Rate (number per second) at which datagrams are sent to the named node by the local node doing the data collection.
Rate (number per second) at which datagrams are received from the named node by the local node doing the data collection.
Rate (number per second) at which datagrams are discarded by the CI port driver because a receive buffer is not available. This is the rate at which datagrams are sent to, but never received by, the named node from the local node doing the data collection.
Rate (number per second) at which sequenced messages are sent to the named node by the local node doing the data collection.
Rate (number per second) at which sequenced messages are received from the named node by the local node doing the data collection.
Metric related to sequenced messages. The number of times that a local node Sysap (system application) had to wait for sufficient “credits” on the target node to become available to complete a transfer. The number of credits is controlled by the system parameter SCSRESPCNT.
Metric related to block transfers. The number of times per second that data was written to a remote node using block mode transfers that were initiated by the local node. This field is zero for all other nodes in the list.
The amount of information, in Kbytes, written to some remote node using block mode transfers that were initiated by the local node. (Used for block transfers, primarily HSC, MSCP, and Connection Manager transfers.) This field is zero for all other nodes in the list.
A process on a remote node does a QIO read from a disk that is hosted locally. The MSCP server on the local node has to read the data from the local disk, then do an SCS Send Data Directive that initiates a block mode transfer to write that data to the remote node.
Metric related to block transfers. The number of times per second that data was read from a remote node using block mode transfers that were initiated by the local node. This field is zero for all other nodes in the list.
The amount of information, in Kbytes, read from a remote node using block mode transfers that were initiated by the local node. (Used for block transfers, primarily HSC, MSCP, and Connection Manager transfers.) This field is zero for all other nodes in the list.
A process on a remote node does a QIO write to a disk that is hosted locally. The MSCP server on the local node has to do an SCS Request Data Directive that initiates a block mode transfer to read from the remote node so that it can write that data to the local disk.
The amount of buffer space, in kilobytes, mapped to receive data from or send data to the named node by the local node doing the data collection. Used for block transfers, primarily HSC, MSCP, and Connection Manager transfers.
Metric related to block transfers. The number of times that a local node Sysap attempted to map a buffer and there were no free buffer descriptor table (BDT) entries available. The number of BDTs is controlled by the system parameter SCSBUFCNT.
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