Provided by: blktrace_1.1.0-2_i386 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)