Dr Andrew Scott G7VAV

MBCS, MIET, Member ACM, Member IEEE

Senior Lecturer
School of Computing
and Communications

D35 InfoLab21
Lancaster University
Lancaster, LA1 4WA
United Kingdom

BLOCKDEV

Section: System Administration (8)
Updated: August 2010
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NAME

blockdev - call block device ioctls from the command line

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

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

-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.

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 sectorsize in bytes - usually 512.
--getsz: Get size in 512-byte sectors.
--rereadpt: Reread partition table
--setbsz bytes: Set blocksize.
--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.

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 from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

for client (none)

Andrew Scott