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SRAW(8)                     System Manager's Manual                    SRAW(8)



NAME
       sraw - benchmark raw scsi I/O performance under linux

SYNOPSIS
       sraw scsi-device [ bstart [ bstep ] ]

DESCRIPTION
       This  program  was  written  because  of all of the whining on the SCSI
       channel about poor performance of the scsi drivers.  This program basi-
       cally  reads  the  specified  scsi  device and measures the throughput.
       Note that the filesystem *AND* the buffer cache are  bypassed  by  this
       code,  this program was designed to benchmark the naked scsi drivers by
       themselves without the need to account for the overhead  of  any  other
       portion of the kernel.

       This  program  does a series of reads of the disk, of consecutive areas
       on the disk.  The device is first queried to determine the sector  size
       for the device, and then the series of reads is begun.  About 5.0 Mb is
       read from the device, and then the performance  numbers  are  reported.
       Note  that  since  the buffer cache is completely bypassed, there is no
       need to be concerned about cache hits or anything.

       Output of sraw is a set  of  lines,  4  numbers  per  line:  blocksize,
       elapsed time, nblocks and throughput (in bytes per second).

OPTIONS
       bstart starting block to check different zones on ZBR discs

       bstep  factor  for  sequential  stepping, default 1.  Use 0 for reading
              always the same blocks (from cache)

AUTHOR
       sraw was written by Eric Youngdale.

AVAILABILITY
       sraw is available at
       ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/



                                   Nov 1993                            SRAW(8)