NAME

       sraw - benchmark raw scsi I/O performance under linux

SYNOPSIS

       sraw [ -fiv6 ] scsi-device [ bstart [ bstep ] ]

DESCRIPTION

       This  program  basically  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. It also could be used to benchmark disk read throughput.

       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).

       scsi-device is either a block device (e.g. /dev/sda, /dev/scd0) or a generic SCSI device (e.g. /dev/sg0).

OPTIONS

       -f     set FUA (Force Unit Access) bit during read. Data is then read  from  media  instead  of  internal
              drive cache.

       -i     use legacy ioctl instead of new SG I/O layer (will not work on 2.6 kernel and block devices).

       -v     more verbose output.

       -6     use  6-bytes  instead  of  10-bytes read command. In this case, only the first GB of data could be
              read from media.

       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)

ERRORS

       sraw could issue input/output errors when reading too many blocks at the same time from  a  block  device
       like /dev/sda. To get rid of them, use /dev/sgN instead.

AUTHOR

       sraw  was first written by Eric Youngdale.  Extensions (-v, -f, -6, SG IO, man page) were written by Eric
       Delaunay.

SEE ALSO

       sg_dd(8) from sg3-utils package.

AVAILABILITY

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

                                                    Nov 1993                                             SRAW(8)