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.

       --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 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.  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 applies 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)