BLOCKDEV(8)                  System Administration                 BLOCKDEV(8)

       blockdev - call block device ioctls from the command line

       blockdev [-q] [-v] command [command...] device [device...]
       blockdev --report [device...]
       blockdev -h|-V

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

       -q     Be quiet.

       -v     Be verbose.

              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.

       It is possible to give multiple devices and multiple commands.

              Flush buffers.

              Get alignment offset.

              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.

              Get discard zeroes support status.

              Get filesystem readahead in 512-byte sectors.

              Get minimum I/O size.

              Get optimal I/O size.

              Get max sectors per request

              Get physical block (sector) size.

              Print readahead (in 512-byte sectors).

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

              Print device size in bytes.

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

              Print logical sector size in bytes - usually 512.

              Get size in 512-byte sectors.

              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).

              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.

              Set read-write.

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

       The blockdev command is part of the util-linux package and is available

util-linux                        August 2010                      BLOCKDEV(8)
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