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Index for Section 8 |
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Alphabetical listing for D |
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diskx(8)
NAME
diskx - disk exerciser program
SYNOPSIS
/usr/field/diskx [ option(s) ] [ parameter(s) ]
DESCRIPTION
The diskx program is intended to test various aspects of disk driver
functionality. These tests provide more comprehensive functional coverage
than the dskx utility. Main functional areas which are tested include:
· Read testing.
· Write testing.
· Seek testing.
· Performance analysis.
Some of the tests involve writing to the disk. For this reason the
exerciser should be used with caution on disks which may contain useful
data which could be over-written. Tests which write to the disk will first
check for the existence of file systems on the test partitions and
partitions which overlap the test partitions. If a file system is found on
these partitions, a prompt will appear asking if testing should continue.
There are a number of options that diskx accepts. These options control
which tests are performed and also specify parameters of test operation.
FLAGS
The following is a description of the diskx options:
-h Help. Displays a help message describing test options and
functionality.
-p Performance test. Read and write transfers will be timed to measure
device throughput. No data validation is performed as part of this
test. Testing will be done using a range of transfer sizes if the -F
option is not specified. The transfer size used for testing a range
of record sizes will start at the minimum value and be incremented by
the reciprocal of the number of specified "splits". For example if
the number of splits is set to 10, the transfer size will start at the
minimum value, the next transfer size will be the minimum value added
to 1/10th of the range of values, similarly the next transfer size
will increase by 1/10th of the range during each testing interval. If
a specific number of transfers are not specified, the transfer count
will be set to allow the entire partition to be read or written; this
number will vary depending on the transfer size and the partition
size. The performance test will run until completed or interrupted
and is not time limited by the -minutes parameter. This test may take
a long time to complete depending on the test parameters.
-r Read-only test. Reads from the specified partitions.
This test is useful for generating system I/O activity. Because it is
a read-only test, it is possible to run more than one instance of the
exerciser on the same disk.
-w Write test. The purpose of this test is to verify that data can be
written to the disk and read back for validation. Seeks are also done
as part of this test. This test provides the most comprehensive
coverage of disk transfer functionality due to the usage of reads,
write, and seeks. The test also combines sequential and random access
patterns.
The test performs the following operations using a range of transfer sizes.
A single transfer size will be utilized if the -F attribute is specified.
The first step is to sequentially write the entire test partition (unless
the number of transfers has been specified using -num_xfer). Next the test
partition is sequentially read. The data read from disk is examined to
insure that it is the same as what was originally written. At this point
if random transfer testing has not been disabled (using the -S attribute)
then writes will be issued to random locations on the partition. After
completion of the random writes, reads will be issued to random locations
on the partition. The data read in from random locations will be examined
for validity.
The following options are testing attributes which modify how tests are to
be run.
-F Perform fixed size transfers. If this option is not specified
transfers will be done using random sizes. This attribute is
associated with the following tests: -p, -r, -w.
-i Interactive mode. Under this mode the user will be prompted for
various test parameters. Typical parameters include the transfer size
and the number of transfers. The following scaling factors are
allowed:
· k or K - kilobyte (1024 * n)
· b or B - block (512 * n)
· m or M - megabyte (1024 * 1024 * n)
For example 10k would specify 10240 bytes.
-O Perform the specified test once. If this option is specified with the
sequential transfer attribute, the test will halt after the entire
disk has been read or written. This attribute is associated with the
-r and -w tests.
-Q Do not perform performance analysis of read transfers. This will
cause only write performance testing to be performed. To perform only
read testing and to skip the write performance tests the -R attribute
must be specified. This attribute is associated with the following
tests: -p.
-R Opens the disk in read-only mode. This attribute is associated with
all tests.
-S Performs sequential transfers. In order to achieve maximum throughput
the -S attribute should be specified on the command line. Transfers
will be performed to sequential disk locations. This may slow down
the observed throughput due to associated head seeks on the device.
If this option is not specified transfers will be done to random disk
locations. This attribute is associated with the following tests: -p,
-r, -w.
-T Directs output to the terminal. This attribute is useful when output
is directed to a logfile using the -o option. By also specifying this
parameter after the -o filename options will cause output to be
directed to both the terminal and the log file. This attribute is
associated with all tests.
-X Does not check for disk labels or partition overlaps. This option
should be used when testing DRD (Distributed Raw Disk) or LSM (Logical
Storage Manager) devices. See the -f and -x options also.
-Y If any of the selected tests write to the disk, the disk will be
examined for any existing file systems. If it appears that file
systems exist, the exerciser will prompt for confirmation before
proceeding. When this attribute is specified the exerciser will NOT
prompt for confirmation before proceeding.
The following options are used to specify test parameters. These options
are followed by an associated parameter specification. Test parameters may
also be modified in an interactive manner. Refer to the description of the
-i test attribute for details. To specify a numerical value, type the
parameter name followed by a space and then the number. For example -
perf_min 512
The following scaling factors are allowed:
· k or K - kilobyte (1024 * n)
· b or B - block (512 * n)
· m or M - megabyte (1024 * 1024 * n)
To illustrate this, -perf_min 10K, causes transfers to be done in sizes of
10240 bytes.
-code
Specifies a code to be imbedded in the high byte of a long word
pattern. This option is only valid with 64 bit patterns, -pattern 8
or -pattern 99. See also the -pattern option. This parameter is
associated only with the -w test option.
-debug
Specifies the level of diagnostic output to display. The higher this
number is, a greater volume of output will be produced describing the
operations the exerciser is performing. This parameter is associated
with all tests.
-err_lines
Specifies the maximum number of error messages may be produced as a
result of an individual test. Limits on error output is done to
prevent a flooding of diagnostic messages in the event of persistent
errors. This parameter is associated with all tests.
-f devname
Used to specify the device special file to perform testing on. The
devname parameter is the name associated with either a block or
character special file which represents the disk to be tested. The
file name must begin with an "r" as in rz0 or rz1. The last character
of the file name may represent the disk partition to test, if no
partitions are specified it is assumed that testing is to be done to
all partitions. For example if the specified devname is /dev/rrz0
then testing will be done to all partitions. If devname is /dev/rrz0a
then testing will be done on only the "a" partition. This parameter
must be specified in order to allow any testing to be performed. This
parameter is associated with all tests.
On a cluster system using DRD devices, or when using LSM, use the -x
option with the -f option to specify the pathname. You must also use
the -X option and specify a value for the the -numb_blocks option when
using -x. (see the example section).
-minutes
Specifies how many minutes to allow testing to continue. This
parameter is associated with the following tests: -r, -w.
-max_xfer
Specifies the maximum transfer size to be performed. When transfers
are to be done using random sizes, the sizes will be within the range
specified by the -max_xfer and -min_xfer parameters. If fixed size
transfers are specified (see the -F test attribute) then transfers
will be done in a size specified by the -min_xfer parameter. Transfer
sizes to the character special file should be specified in multiples
of 512 bytes. If the specified transfer size is not an even multiple
the value will be rounded down to the nearest 512 bytes. This
parameter is associated with the following tests: -r, -w.
-min_xfer
Specifies the minimum transfer size to be performed. This parameter
is associated with the following tests: -r, -w.
-num_blocks
Specifies the range of disk blocks that diskx should use. Use this
option when testing DRD devices or when using LSM.
-num_xfer
Specifies how many transfers to perform before changing the partition
that is currently being tested. This parameter is only useful when
more than one partition is being tested. If this parameter is not
specified then the number of transfers will be set to be enough to
completely cover a partition. This parameter is associated with the
following tests: -r, -w.
-o filename
Sends output to the specified filename. The default is to not create
an output file and send output to the terminal. This parameter is
associated with all tests.
-pattern #
This option specifies the write pattern to be used when exercising a
disk.
· 1 indicates a byte pattern (8 bits)
· 2 indicates a short word pattern (16 bits)
· 4 indicates a int word pattern (32 bits)
· 8 indicates a long word pattern (64 bits)
· 99 indicates a repeating pattern (64 bits)
The default is a long word pattern (64 bits). This parameter is
associated only with the -w test option. See also the -code option.
-perf_max
Specifies the maximum transfer size to be performed. When transfers
are to be done using random sizes, the sizes will be within the range
specified by the -perf_min and -perf_max parameters. If fixed size
transfers are specified (see the -F test attribute) then transfers
will be done in a size specified by the -perf_min parameter. This
parameter is associated with the following tests: -p.
-perf_min
Specifies the minimum transfer size to be performed. This parameter
is associated with the following tests: -p.
-perf_splits
Specifies how the transfer size will be changed when testing a range
of transfer sizes. The range of transfer sizes is divided by
perf_splits to obtain a transfer size increment. For example if
perf_splits is set to 10, tests will be run by starting with the
minimum transfer size and increasing the size by 1/10th of the range
of values for each test iteration. The last transfer size will be set
to the specified maximum transfer size. This parameter is associated
with the following tests: -p.
-perf_xfers
Specifies the number of transfers to be performed in performance
analysis. If this value is not explicitly specified the number of
transfers will be set equal to the number required to read the entire
partition. This parameter is associated with the following tests: -p.
-x Specifies that the pathname quoted should be used without specifying
partition letters. This is useful when testing a DRD (Distributed Raw
Device) in a cluster, or when LSM is in use.
EXAMPLES
The following are example command lines with a description of what the
resulting test action will be.
diskx -f /dev/rrz0 -r
The above example will perform read-only testing on the character device
special file that rrz0 represents. Since no partition is specified,
reading will be done from all partitions. The default range of transfer
sizes will be used. Output from the exerciser program will be displayed on
the terminal.
diskx -x -X -f /dev/rdrd/drd1 -r -num_blocks 100000
diskx -x -X -f /dev/vol/vol1 -r -num_blocks 100000
The above examples performs read-only testing. The first example specifies
a DRD device, and the second an LSM volume.
diskx -f /dev/rz0a -o diskx.out -p -n -S
Performance tests will be run in the "a" partition of rz0. Program output
will be logged to the file diskx.out. The -S option will cause sequential
transfers for best test results. Testing will be done over the default
range of transfer sizes.
diskx -f /dev/rrz0 -r &; diskx -f /dev/rrz1 -r &; diskx -f /dev/rrz2 -r &
This command will run the read test on all partitions of the disks. The
disk exerciser is being invoked here as 3 separate processes. In this
manner the 3 processes will be generating a lot of system I/O activity.
This may be useful for system stress testing purposes.
diskx -f /dev/rrz17b -w -pattern 99
This command will run the write test on partition "b" of rz17. The
repeating long word pattern will write the following test pattern to the
disk:
resulting test pattern written:
<address> <quad word> <quad word>
0000020 0007060504030201 0007060504030201
0000030 0007060504030201 0007060504030201
0000040 0007060504030201 0007060504030201
diskx -f /dev/rrz17b -w -pattern 8 -code 255
This command will run the write test on partition "b" of rz17. The
specified pattern and code will write the following test pattern to the
disk:
resulting test pattern written:
<address> <quad word> <quad word>
0000020 ff00000000000004 ff00000000000005
0000030 ff00000000000006 ff00000000000007
0000040 ff00000000000008 ff00000000000009
PROGRAM OUTPUT
The following are descriptions of some of the tables which are produced by
the disk exerciser:
This is the header used to describe the results of the transfer tests
followed by a description of each column:
Disk Transfer Statistics
Part Seeks Seek_Er Writes Writ_Er MB_Write Reads Read_Er MB_Read Data_Er
Part A letter used to represent the disk partition.
Seeks The number of seek system calls that were issued.
Seek_Er
The number of seek system calls returning error status.
Writes The number of write system calls issued.
Writ_Er
The number of write system calls returning error status.
MB_Write
The number of megabytes of data written.
Reads The number of read system calls issued.
Read_Er
The number of read system calls returning error status.
MB_Read
The number of megabytes of data read.
Data_Er
The number of transfers which had data validation errors. This does
not specify the number of bytes that were in error; rather it
specifies that the transfer had at least one byte in error.
This header is used to describe the results of the performance tests.
Performance test results:
Part- Transfer Count of Read Write Transfer
ition Size Transfers Rate Rate Errors
Partition
A letter used to represent the disk partition.
Transfer Size
This is the size of the read or write system call.
Count of Transfers
Specifies the number of read or write system calls.
Read Rate
The observed disk throughput obtained by timing the specified number
of read system calls.
Write Rate
The observed disk throughput obtained by timing the specified number
of write system calls.
Transfer Errors
Shows how many read and write system calls resulted in a return
value of error status. If this value is nonzero then the values
displayed in the Read and Write Rate columns may not accurately
reflect correct device performance.
RELATED INFORMATION
getdiskbyname(3), disktab(4), cmx(8), fsx(8), shmx(8), tapex(8), memx(8)
See also the Trucluster(TM) Administration guide.