ClearCase Reference Manual, Release 4.0, Windows

mvfsstat

Displays MVFS statistics

APPLICABILITY

ClearCase (administrative command)

SYNOPSIS

mvfsstat [ -iIcrvVhalzAd ] [ -o outfile] [ time ] [ count ]

DESCRIPTION

NOTE: This utility is not intended for general use. It is intended primarily to help ClearCase engineering and Rational Technical Support personnel diagnose problems with the MVFS. For information on improving ClearCase client performance, see Administering ClearCase.

The mvfsstat command displays MVFS usage and operating statistics, including cumulative statistics on MVFS cache usage, rpc statistics, cleartext I/O counts, vnode operation counts, and VFS operation counts. This data is useful for evaluating file-system performance and determining whether MVFS cache sizes require adjustment.

MVFS CACHE STATISTICS

The -c option reports on the usage of the host's MVFS caches. This report is cumulative, covering the entire period since the MVFS was reloaded. The following example covers a 23-day period:

----------------- Fri Jul 16 16:20:16 1999 --------------------- dnlc: 2267082 2229727( 98.4%) hit 1301984 dot 846301 dir 62901 reg 18541 noent 37355( 1.6%) miss 25099 events 42761( 1.9%) add 27820 dir 7368 reg 7573 noent attr: 2355186 2349946( 99.8%) hit 120 lvut 5240( 0.2%) miss (3902cto+0gen+970timo+74new,294ev;35lvut) 57302 updates 5546unexp+2206exp mod, 2295 vmod

The following sections describe the particular statistics that are useful in tuning MVFS performance on a ClearCase client host.

Directory Name Lookup Cache (dnlc)

The dnlc section reports on usage of a name-lookup cache that maps pathnames to ClearCase identifiers. Note that the value precedes the keyword. For example, 1301984 dot means that the reported value of the "dot" statistic is 1301984.

Cache Hits. The hit line reports on the number of times an entry type was found in the cache (hit):

`dot`	Number of times the current working directory was looked up (always a cache hit)
`dir`	Number of times a directory object entry was found in the cache.
`reg`	Number of times a file object entry was found in the cache.
`noent`	Number of times a cached `File not found` (`ENOENT`) entry was found.

This cache has low hit rates (around 50%) for activities that walk a large tree-for example, a find command, or a recursive clearmake that examines many files and determines that nothing needs to be built.

Cache Misses. The miss line reports on total cache misses. The events value is the number of cache misses that occurred because of a significant VOB event, a time-out of the entry, or vnode recycling. Cache misses can occur because there was no entry in the cache. The total number of cache misses equals the events value plus the number of misses occurring because there was no entry in the cache.

Cache Additions. The add line reports on cache misses that occurred because a new entry was being added to the cache. The additions are categorized as directory entries (dir), file entries (reg), and ENOENT entries (noent).

Attribute Cache

The attr section reports on usage of a cache of object status inquiry records. This cache generally has hit rates comparable to that for the directory name lookup cache.

OPTIONS AND ARGUMENTS

time: Time in seconds between samples. Display deltas on each sample. If you omit this option, only the absolute values of all information are printed.

count: Number of samples. If omitted, defaults to "infinite".

-o outfile: Writes the output to outfile.

-i: Display cleartext I/O counts and wait times.

-I: Display count and wait times for the NT I/O Request Packets that the MVFS has processed.

-c: Display statistics for the MVFS caches, as described in MVFS CACHE STATISTICS above.

-r: Display MVFS remote-procedure-call (RPC) statistics. These statistics include both counts and real-time waited. Real-time waited may be greater than 100% of a sample period in two cases:

When an operation took longer to complete than the sample period; for example, 60 seconds of wait time is recorded in a 30-second sample.

Multiple processes are waiting at the same time.

: In general, real-time percentages are meaningful only when a single process is accessing a VOB.

-v: Displayscounts of vnode operations.

-V: Displays counts of vfs operations.

-h: Displays an RPC histogram. Cleartext fetch RPCs are tallied separately from all other RPCs.

-a: Displays auditing statistics.

-l: Adds more detail to the statistics generated by -c, -r, -i, -I, -v, and/or -V, by providing a breakdown by individual operations. With -c, also provides per-cache-entry hit ratios.

-z: Must be local administrator or a member of the Administrators group. Resets all running counters to zero.

-A: Displays all statistics.

-d: With -c or -A, displays additional debugging information for use in diagnosing problems. Use this option only under direction from Rational Technical Support.