blockdev(8)

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...]
       blockdev -h|-V

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

OPTIONS
       -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.

       -h, --help
              Display help text and exit.

       -V, --version
              Print version and exit.

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

       --flushbufs
              Flush buffers.

       --getalignoff
              Get alignment offset.

       --getbsz
              Print  blocksize  in  bytes.  This size does not describe device
              topology.  It's size used internally by kernel and it maybe mod-
              ified (for example) by filesystem driver on mount.

       --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 read-only. Print 1 if the device is read-only, 0 otherwise.

       --getsize64
              Print device size in bytes.

       --getsize
              Print  device  size (32-bit!) in sectors. Deprecated in favor of
              the --getsz option.

       --getss
              Print logical sector size in bytes - usually 512.

       --getsz
              Get size in 512-byte sectors.

       --rereadpt
              Reread partition table

       --setbsz bytes
              Set blocksize. Note that the block size is specific to the  cur-
              rent  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. The currently active access to the device may not
              be affected  by  the  change.  For  example  filesystem  already
              mounted  in read-write mode will not be affected. The change ap-
              plies after remount.

       --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 https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                        August 2010                      BLOCKDEV(8)