btrecord man page on Oracle

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BTRECORD(8)							   BTRECORD(8)

       btrecord - recreate IO loads recorded by blktrace


       btrecord [ options ] <dev...>

       The  btrecord  and  btreplay  tools  provide  the ability to record and
       replay IOs captured by the blktrace utility. Attempts are made to main‐
       tain 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.
	   the only traces you are interested in are QUEUE requests —
	   thus,  to save system resources (including storage for traces), one
	   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

       -d <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>
	      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 (.).

	      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 (.).

	      Show help and exit.

	      Show version number and exit.

       -m <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>
	      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

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

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

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

		  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.

	      Enable verbose output.  This option will output some simple sta‐
	      tistics 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:

		   The first field contains the device name  and  CPU  identi‐
		 fier. Thus:
		   sdab:0: means the device sdab and traces on CPU 0.

		   The	second field contains the total number of packets pro‐
		 cessed for each
		   device file.

		   The next field shows the number  of	packets	 eligible  for

		   The fourth field contains the total number of IO bunches.

		   The	last  field  shows the average number of IOs per bunch

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

       Report bugs to <>

       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
       <>.	 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  Pub‐
       lic License, version 2.
       On  Debian  systems,  the text of the GNU General Public License can be
       found in /usr/share/common-licenses/GPL-2.

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

blktrace git-20071207142532    December	 8, 2007		   BTRECORD(8)

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