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# BE Director (DA) metrics

The Unisphere Performance Management application enables the user to gather, view, and analyze performance data to troubleshoot and optimize the storage systems.

Within the PM metrics section, V4 is used to denote that the metric is supported only by a storage system (array) running PowerMaxOS 10 (6079). V3 is used to denote that the metric is supported only by a storage system (array) running HYPERMAX OS 5977 or PowerMaxOS 5978. Metrics without the denotation are supported by all storage systems (arrays).

The following table lists all metrics that are available for back-end directors.

Table 1. BE director (DA) metrics
Metric | Description
--- | ---
% Busy | The percent of time that a director is busy (numerator_delta/denominator_delta) * 100
% Read Reqs | The percent of read requests out of the total requests.
% Write Reqs | The percent of write requests out of the total requests.
Avg Time per Syscall | The average time spent processing all system calls.
Clone Copy Read | Measures, in tracks/sec, the backend read traffic that is not immediately associated to front-end I/O.
Clone Copy Write | Measures, in tracks/sec, the backend write traffic that is not immediately associated to front-end I/O.
lOs/sec | The number of I/Os performed each second by the director.
Optimized Write | Internal metric
PHCO Rebuild Copy | Internal metric
PHCO Rebuild Read | Internal metric
Prefetched Tracks/sec | The number of tracks prefetched from disk to cache upon detection of a sequential read stream.
Read Reqs/sec | A data transfer of a read between the director and the cache
Reqs/sec | A data transfer between the director and the cache - an I/O may require multiple requests depending on I/O size, alignment or both. For writes the request counter increments at the time that the write pending flag is removed from the cache slot. If multiple DAs are involved in the I/Os operation (such as RAID 1), the request count may not reconcile with the I/Os count and I/O size.
Syscall Count/sec | The total number of calls seen by this director
Syscall RDF Dir Count/sec | The number of calls sent using SRDF to a remote system.
Syscall Remote Dir Count/sec | The number of calls that are sent from the local director to another director in the same system
Syscall Time | Total time that is spent processing all system calls
Throughput | The total I/O (reads and writes) per second in MBs
Throughput Read | The number of reads per second in MBs
Throughput Written | The number of writes per second in MBs
Write Reqs/sec | A data transfer of a write between the cache and the director