Provided by: sg3-utils_1.17-2_i386 bug

NAME

       sg_readcap - calls a READ CAPACITY command on a SCSI device

SYNOPSIS

       sg_readcap [-16] [-h] [-lba=<block>] [-pmi] [-v] [-V] <device>

DESCRIPTION

       The  normal  usage  is to find the number of blocks (and block size) of
       the given device and output them.

       The SCSI READ CAPACITY command (both 10  and  16  byte  cdbs)  actually
       yield  the  block  address  of  the  last block and the block size. The
       number of blocks is thus one plus the block address of the  last  block
       (as blocks are counted origin zero (i.e. starting at block zero)). This
       is the source of many "off by one"  errors  which  are  often  seen  as
       medium or out of range errors when the reported last block is read.

       Device  capacity is the product of the number of blocks and block size.
       This utility outputs this figure in bytes, MiB (1048576 bytes per  MiB)
       and GB (1000000000 bytes per GB).

       -16    Use  the  16  byte cdb variant of the READ CAPACITY command. The
              default action is to use the 10 byte cdb  variant  which  limits
              the  maximum  block  address  to (2**32 - 2). When a 10 byte cdb
              READ CAPACITY command is used on a  device  whose  size  is  too
              large  then  a  last block address of 0xffffffff is returned (if
              the device complies with SBC-2).

       -b     utility outputs two hex numbers (prefixed with  ’0x’  and  space
              separated)  to stdout. The first number is the maximum number of
              blocks on the device (which is one plus  the  lba  of  the  last
              accessible  block). The second number is the size of each block.
              If the operation fails then "0x0 0x0" is writtent to stdout.

       -h     output the usage message then exit.

       -lba=<block>
              used in conjunction with "-pmi" option.  This  variant  of  READ
              CAPACITY will yield the last block address after "<block>" prior
              to a delay. For a disk, given a "<block>" address it yields  the
              highest  numbered  block  on  the same cylinder (i.e. before the
              heads need to move). "<block>" is in hex (from  0  to  ffffffff)
              and defaults to zero.

       -pmi   partial  medium  indicator:  for  finding the next block address
              prior to some delay (e.g. head movement). In the absence of this
              switch,  the  total  number  of blocks and the block size of the
              device are output.

       -v     verbose: print out cdb of issued commands  prior  to  execution.
              ’-vv’ and ’-vvv’ are also accepted yielding greater verbosity.

       -V     outputs version string then exits.

       On  exit  this  utility  returns  0 if it succeeded otherwise a process
       status value of 1 is returned.

       In the 2.4 series of Linux kernels the given  device  must  be  a  SCSI
       generic  (sg)  device.  In the 2.6 series block devices (e.g. disks and
       SCSI DVDs) can also be specified. For example "sg_readcap /dev/sda" and
       "sg_readcap  /dev/hdd" (if /dev/hdd is a ATAPI CD/DVD device) will work
       in the 2.6 series kernels.

AUTHORS

       Written by Douglas Gilbert

COPYRIGHT

       Copyright © 1999-2005 Douglas Gilbert
       This software is distributed under the  GPL  version  2.  There  is  NO
       warranty;  not  even  for  MERCHANTABILITY  or FITNESS FOR A PARTICULAR
       PURPOSE.