diskx(8) System Manager's Manual diskx(8)
NAME
diskx - disk exerciser program
SYNOPSIS
/usr/field/diskx [option(s)] [parameter(s)]
OPTIONS
The following is a description of the diskx options: Help. Displays a help message describing test options and functionality. 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.
To achieve maximum throughput, specify the -S option to cause sequential transfers. If the sequential attribute is not specified,
transfers will be done to random locations which may slow down the throughput due to associated head seeks on the device. 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. Use the -num_xfer option with the -r option. 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. (Stop on error.) This causes testing to halt upon
detection of all errors except data validation errors and the accumulated test results will be displayed. This option is associated with
the -p, -r, and -w tests. (Stop on Data Validation error.) This causes testing to halt upon detection of a data validation error. The
accumulated test results will be displayed. The failing LBA and 10 lines of the data expected and the data returned will also be displayed.
This option is associated with the -w test. 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. 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 fac-
tors 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. Perform the specified test once. If this option is specified with the sequential trans-
fer attribute, the test will halt after the entire disk has been read or written. This attribute is associated with the -r and -w
tests. 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. Opens the disk in read-only mode. This attribute is associated with all tests. Performs sequential
transfers. In order to achieve maximum throughput the -S attribute should be specified on the command line. Transfers will be per-
formed 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. 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. 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. 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. 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. 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. 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. Specifies
which device special file to test. The devname parameter is the name associated with either a block or character special file which repre-
sents the disk to be tested. The device special files are located in /dev/disk and named dskNx, where N is the number of the device and x
is a letter representing the partition. For example, /dev/disk/dsk0a refers to partition a of disk 0. If no partition is specified, it is
assumed that testing is to be done to all partitions. For example if the specified devname is /dev/disk/dsk0 then testing will be done to
all partitions. For raw device names, you must specify the device special files in the /dev/rdisk directory, which have the same dskNx for-
mat. For example, /dev/rdisk/dsk0a. This parameter must be specified and 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 EXAMPLES section). Specifies how
many minutes to allow testing to continue. This parameter is associated with the following tests: -r, -w. 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. Specifies the minimum transfer size to be performed. This parameter is
associated with the following tests: -r, -w. Specifies the range of disk blocks that diskx should use. Use this option when test-
ing DRD devices or when using LSM. 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. 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. 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.
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.
Specifies the minimum transfer size to be performed. This parameter is associated with the following tests: -p. 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. 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 num-
ber required to read the entire partition. This parameter is associated with the following tests: -p. Specifies not to apply parti-
tion logic & checks. This flag is most likely to be used when pseudo device drivers such as DRD (Distributed Raw Disk) or LSM
(Logical Storage Manager) are being used and the device type has no partitions. In such cases, the device special file as specified
on the command line is used rather than a constructed name that appends a letter signifying the partition. When using -x with the
read, write, and performance tests you must specify the number of blocks on the device using the -num_blocks option. (Without any
partition logic it is impossible for disks to automatically size the partition.)
DESCRIPTION
The diskx program is intended to test various aspects of disk driver functionality. These tests provide more comprehensive functional cov-
erage 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.
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
A letter used to represent the disk partition. The number of seek system calls that were issued. The number of seek system calls return-
ing error status. The number of write system calls issued. The number of write system calls returning error status. The number of
megabytes of data written. The number of read system calls issued. The number of read system calls returning error status. The number of
megabytes of data read. 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
A letter used to represent the disk partition. This is the size of the read or write system call. Specifies the number of read or write
system calls. The observed disk throughput obtained by timing the specified number of read system calls. The observed disk throughput
obtained by timing the specified number of write system calls. 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.
EXAMPLES
The following are example command lines with a description of what the resulting test action will be. The example below will perform read-
only testing on the character device special file that dsk0 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
-f /dev/rdisk/dsk0 -r The following example performs read-only testing on an LSM volume. diskx -x -X -f /dev/vol/vol1 -r -num_blocks
100000 Performance tests will be run in the "a" partition of dsk0. 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/disk/dsk0a
-o diskx.out -p -n -S 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/rdisk/dsk0 -r &; diskx -f /dev/rdisk/dsk1 -r &; diskx -f /dev/rdisk/dsk2 -r & This command will run the
write test on partition "b" of disk 17. diskx -f /dev/rdisk/dsk17b -w -pattern 99
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 ... This command will run the write test on partition "b" of disk 17. diskx -f /dev/rdisk/dsk17b
-w -pattern 8 -code 255
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 ...
SEE ALSO
Commands: cmx(8), fsx(8), memx(8), shmx(8), tapex(8)
Functions: getdiskbyname(3)
Files: disktab(4)
Cluster Administration
diskx(8)