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BLOCKDEV(8)                                     System Administration                                     BLOCKDEV(8)



NAME
       blockdev - call block device ioctls from the command line

SYNOPSIS
       blockdev [-q] [-v] command [command...]  device [device...]
       blockdev --report [device...]

DESCRIPTION
       The utility blockdev allows one to call block device ioctls from the command line.

OPTIONS
       -V     Print version and exit.

       -q     Be quiet.

       -v     Be verbose.

       --report
              Print a report for the specified device. It is possible to give multiple devices. If none is given, all
              devices which appear in /proc/partitions are shown. Note that the partition  StartSec  is  in  512-byte
              sectors.

COMMANDS
       It is possible to give multiple devices and multiple commands.

       --flushbufs
              Flush buffers.

       --getalignoff
              Get alignment offset.

       --getbsz
              Print blocksize in bytes.

       --getdiscardzeroes
              Get discard zeroes support status.

       --getfra
              Get filesystem readahead in 512-byte sectors.

       --getiomin
              Get minimum I/O size.

       --getioopt
              Get optimal I/O size.

       --getmaxsect
              Get max sectors per request

       --getpbsz
              Get physical block (sector) size.

       --getra
              Print readahead (in 512-byte sectors).

       --getro

              Get size in 512-byte sectors.

       --rereadpt
              Reread partition table

       --setbsz bytes
              Set  blocksize.  Note  that the block size is specific to the current file descriptor opening the block
              device, so the change of block size only persists for as long as blockdev has the device open,  and  is
              lost once blockdev exits.

       --setfra sectors
              Set filesystem readahead (same like --setra on 2.6 kernels).

       --setra sectors
              Set readahead (in 512-byte sectors).

       --setro
              Set read-only.

       --setrw
              Set read-write.

AUTHOR
       blockdev was written by Andries E. Brouwer and rewritten by Karel Zak.

AVAILABILITY
       The   blockdev   command   is   part   of   the  util-linux  package  and  is  available  from  ftp://ftp.ker‐
       nel.org/pub/linux/utils/util-linux/.




util-linux                                           August 2010                                          BLOCKDEV(8)