dasdstat - Display DASD performance statistics

Red Hat Enterprise Linux 9.2 LPAR mode z/VM guest KVM guest

Use the dasdstat command to display DASD performance statistics, including statistics about Parallel Access Volume (PAV) and High Performance Ficon.

This command includes and extends the performance statistics that is also available through the tunedasd command.

Before you begin: debugfs must be mounted, see debugfs.

dasdstat syntax

Read syntax diagramSkip visual syntax diagramdasdstat -e1 -d -r -l -V -c  <colnum> -w  <width> -i  <directory>  <item>
Notes:
  • 1 Omit the -e, -d, and -r options to read statistics.

Where:

-e or --enable
starts statistics data collection.
-d or --disable
stops statistics data collection.
-r or --reset
sets the statistics counters to zero.
-l or --long
displays more detailed statistics information, for example, differentiates between read and write requests.
-V or --verbose
displays more verbose command information.
-c <colnum> or --columns <colnum>
formats the command output in a table with the specified number of columns. The default is 16. Each row gets wrapped after the specified number of lines.
-w <width> or --column-width <width>
sets the minimum width, in characters, of a column in the output table.
-i <directory> or --directory <directory>
specifies the directory that contains the statistics. The default is <mountpoint>/dasd, where <mountpoint> is the mount point of debugfs. You need to specify this parameter if the dasdstat command cannot determine this mount point or if the statistics are copied to another location.
<item>
limits the command to the specified items. For <item> you can specify:
  • global for summary statistics for all available DASDs.
  • The block device name by which a DASD is known to the DASD device driver.
  • The bus ID by which a DASD is known as a CCW device. DASDs that are set up for PAV or HyperPAV have a CCW base device and, at any one time, can have one or more CCW alias devices for the same block device. Alias devices are not permanently associated with the same block device. Statistics that are based on bus ID, therefore, show additional detail for PAV and HyperPAV setups.

If you do not specify any individual item, the command applies to all DASD block devices, CCW devices, and to the summary.

-v or --version
displays the version number of dasdstat, then exits.
-h or --help
displays help information for the command.

Examples

  • This command starts data collection for dasda, 0.0.b301, and for a summary of all available DASDs. 
    # dasdstat -e dasda 0.0.b301 0.0.b302 global
  • This command resets the statistics counters for dasda. 
    # dasdstat -r dasda
  • This command reads the summary statistics: 
    statistics data for statistic: global
start time of data collection: Wed Aug 17 09:52:47 CEST 2011

3508 dasd I/O requests
with 67616 sectors(512B each)
0 requests used a PAV alias device
3458 requests used HPF
 __<4 ___8 __16 __32 __64 _128 _256 _512 __1k __2k __4k __8k _16k _32k _64k 128k
 _256 _512 __1M __2M __4M __8M _16M _32M _64M 128M 256M 512M __1G __2G __4G _>4G
Histogram of sizes (512B secs)
    0    0 2456  603  304  107   18    9    3    8    0    0    0    0    0    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0
Histogram of I/O times (microseconds)
    0    0    0    0    0    0  100 1738  813  725   30   39   47   15    1    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0
Histogram of I/O time till ssch
    0    0  901  558  765   25   28  288  748  161   17   16    1    0    0    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0
Histogram of I/O time between ssch and irq
    0    0    0    0    0    0  316 2798  283   13   19   22   41   15    1    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0
Histogram of I/O time between irq and end
    0 3023  460    8    4    9    4    0    0    0    0    0    0    0    0    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0
# of req in chanq at enqueuing (0..31) 
 ___0 ___1 ___2 ___3 ___4 ___5 ___6 ___7 ___8 ___9 __10 __11 __12 __13 __14 __15
 __16 __17 __18 __19 __20 __21 __22 __23 __24 __25 __26 __27 __28 __29 __30 __31
    0 2295  319  247  647    0    0    0    0    0    0    0    0    0    0    0
    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0    0