Provided by: blktrace_1.1.0-2_amd64 bug

NAME

       btrecord - recreate IO loads recorded by blktrace

SYNOPSIS

       Usage:

       btrecord [ options ] <dev...>

DESCRIPTION

       The  btrecord  and btreplay tools provide the ability to record and replay IOs captured by
       the blktrace utility. Attempts are made to  maintain  ordering,  CPU  mappings  and  time-
       separation of IOs.

       The  blktrace  utility provides the ability to collect detailed traces from the kernel for
       each IO processed by the block IO layer. The traces provide a complete timeline  for  each
       IO  processed,  including detailed information concerning when an IO was first received by
       the block IO layer — indicating the device, CPU number, time stamp, IO  direction,  sector
       number  and IO size (number of sectors). Using this information, one is able to replay the
       IO again on the same machine or another set up entirely.

       The basic operating work-flow to replay IOs would be something like:

       -
           Run blktrace to collect traces. Here you specify the
           device or devices that you wish to trace and later replay IOs upon. Note:
           the only traces you are interested in are QUEUE requests —
           thus, to save system resources (including storage for traces), one could
           specify the -a queue command line option to blktrace.

       -
           While blktrace is running, you run the workload that you
           are interested in.

       -
           When the work load has completed, you stop the blktrace
           utility (thus saving all traces over the complete workload).

       -
           You extract the pertinent IO information from the traces saved by
           blktrace using the btrecord utility. This will parse
           each trace file created by blktrace, and crafty IO descriptions
           to be used in the next phase of the workload processing.

       -
           Once btrecord has successfully created a series of data
           files to be processed, you can run the btreplay utility which
           attempts to generate the same IOs seen during the sample workload phase.

OPTIONS

       -d <dir>
       --input-directory=<dir>
              Set input directory.   This  option  requires  a  single  parameter  providing  the
              directory  name for where input files are to be found. The default directory is the
              current directory (.).

       -D <dir>
       --output-directory=<dir>
              Set output directory.  This  option  requires  a  single  parameter  providing  the
              directory name for where output files are to be found. The default directory is the
              current directory (.).

       -F
       --find-traces
              Find trace files automatically This option instructs btreplay to go  find  all  the
              trace files in the directory specified (either via the -d option, or in the default
              directory (.).

       -h
       --help
              Show help and exit.

       -V
       --version
              Show version number and exit.

       -m <nanoseconds>
       --max-bunch-time=<nanoseconds>
              The -m option requires a single parameter which specifies an  amount  of  time  (in
              nanoseconds)  to  include  in  any  one  bunch of IOs that are to be processed. The
              smaller the value, the smaller the number of IOs processed at one  time  —  perhaps
              yielding  in  more  realistic replay.  However, after a certain point the amount of
              overhead per bunch may result in additional real replay time,  thus  yielding  less
              accurate replay times.

              The default value is 10,000,000 nanoseconds (10 milliseconds).

       -M <num>
       --max-pkts=<num>
              Set maximum number of packets per bunch.  The -M option requires a single parameter
              which specifies the maximum number of IOs to store in a single bunch. As  with  the
              -m option, smaller values may or may not yield more accurate replay times.

              The default value is 8, with a maximum value of up to 512 being supported.

       -o <basename>
       --output-base=<basename>
              Set base name for output files.  Each output file has 3 fields:

              1.
                  Device identifier (taken directly from the device name of the
                  blktrace output file).

              2.
                  btrecord base name — by default ``replay''.

              3.
                  The CPU number (again, taken directly from the
                  blktrace output file name).

              This  option  requires  a  single  parameter  that  will  override the default name
              (replay), and replace it with the specified value.

       -v
       --verbose
              Enable verbose output.  This option will output some simple statistics at  the  end
              of a successful run.  Example output is:

              sdab:0: 580661 pkts (tot), 126030 pkts (replay), 89809 bunches, 1.4 pkts/bunch
              sdab:1: 2559775 pkts (tot), 430172 pkts (replay), 293029 bunches, 1.5 pkts/bunch
              sdab:2: 653559 pkts (tot), 136522 pkts (replay), 102288 bunches, 1.3 pkts/bunch
              sdab:3: 474773 pkts (tot), 117849 pkts (replay), 69572 bunches, 1.7 pkts/bunch

              The meaning of the columns is:

              1.
                   The first field contains the device name and CPU identifier. Thus:
                   sdab:0: means the device sdab and traces on CPU 0.

              2.
                   The second field contains the total number of packets processed for each
                   device file.

              3.
                   The next field shows the number of packets eligible for replay.

              4.
                   The fourth field contains the total number of IO bunches.

              5.
                   The last field shows the average number of IOs per bunch recorded.

AUTHORS

       btrecord  was  written  by  Alan D. Brunelle.  This man page was created from the btreplay
       documentation by Bas Zoetekouw.

REPORTING BUGS

       Report bugs to <linux-btrace@vger.kernel.org>

COPYRIGHT

       Copyright © 2007 Alan D. Brunelle, Alan D. Brunelle and Nathan Scott.
       This is free software.  You may redistribute copies of it  under  the  terms  of  the  GNU
       General  Public  License <http://www.gnu.org/licenses/gpl.html>.  There is NO WARRANTY, to
       the extent permitted by law.
       This manual page was created for Debian  by  Bas  Zoetekouw.   It  was  derived  from  the
       documentation  provided  by the authors and it may be used, distributed and modified under
       the terms of the GNU General Public License, version 2.
       On Debian  systems,  the  text  of  the  GNU  General  Public  License  can  be  found  in
       /usr/share/common-licenses/GPL-2.

SEE ALSO

       The  full  documentation  for  btreplay  can be found in /usr/share/doc/blktrace on Debian
       systems.
       blktrace (8), blkparse (1), btreplay (8)