qiostat(1)qiostat(1)NAMEqiostat - VxFS Quick I/O for Databases statistics utility
SYNOPSIS
/opt/VRTS/bin/qiostat [ -i interval [ -c count] ] [ -l ]
[ -o local ] [ -r ] filename ...
AVAILABILITY
VRTSvxfs
DESCRIPTIONqiostat prints and resets statistics on one or more VERITAS Quick I/O
for Databases device files.
qiostat reads statistics for the specified Quick I/O files and prints
them to standard output. These statistics show I/O activity since the
last time the file was opened from the Quick I/O interface, and are
valid as long as the file remains open. Statistics reset to zero when
the last file open from the Quick I/O interface is closed.
Cluster File System Issues
Quick I/O works on VxFS cluster file systems, but Cached Quick I/O is
not currently supported.
OPTIONS-c count Stops after printing statistics count times.
-i interval
Prints updated I/O statistics every interval seconds. The
first set of statistics reported are the totals since the
last reset. Subsequent displays show the changes since the
last report.
-l Prints the statistics in long format. Also prints the
caching statistics when Cached Quick I/O is enabled.
-o local For a cluster Quick I/O file, the default behavior of qiostat
is to display the sum of the statistics from all the cluster
nodes where the file is opened through the Quick I/O inter‐
face. When the -o local option is specified, only the local
node statistics are displayed. Similarly, if used with the
-r option, only the local node statistics are reset.
-r Resets statistics instead of printing them. This follows the
same selection rules as printing for any device file. If
interval is also specified, the first set of statistics are
not printed because they were already reset to zero; subse‐
quent activity prints statistics as usual.
Output Format
Summary statistics for each object are printed in single line output
records, preceded by two header lines. The output line consists of
blank-separated fields for the file name, and statistics on read and
write operations:
· number of read operations
· number of write operations
· number of blocks read
· number of blocks written
· average time spent on read operations in the interval
· average time spent on write operations in the interval
If the -i interval option is supplied, statistics are prefaced with a
time stamp showing the current local time on the system.
If the -l option is specified, statistics are printed in two lines per
object:
FILE NAME READ WRITE READ WRITE READ WRITE
CREAD PREAD HIT RATIO
cust0 2 1 8 4 5.0 10.0
2 1 50.0
The first line is the same as described above. The second line shows
the caching statistics. Cached Quick I/O performs buffered reads and
returns cached data (if available) without doing reads from the disk.
Writes are performed as modified direct writes, that is, after the
direct write to disk is scheduled, the file system updates the copy of
data in cache (if it exists) with the same data being written to disk.
In the column headings of the second line:
· CREAD is the number of reads issued to cache
· PREAD is the number of reads to the disk required because the
data was not available in cache
· HIT RATIO is the percentage of the read requests that did not
have to perform physical I/O and were satisfied from the cache
(CREADs - PREADs / CREADs = HIT RATIO)
EXIT CODESqiostat exits with a non-zero status if the attempted operation fails.
A non-zero exit code is not a complete indicator of the problems
encountered, but rather denotes the first condition that prevented fur‐
ther execution of the command.
EXAMPLES
Display statistics for all device files on the file system /mnt/oracle:
qiostat /mnt/oracle/∗
Display five sets of I/O statistics at 10 second intervals:
qiostat-i 10 -c 5 /mnt/oracle/∗
Print cache statistics:
qiostat-l /mnt/oracle/∗
SEE ALSOqioadmin(1), qiomkfile(1)VxFS 5.0 7 Jan 2008 qiostat(1)