BLOCKDEV

Section: System Administration (8)
Updated: August 2010
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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 modified (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 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.
 

AUTHORS

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/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
COMMANDS
AUTHORS
AVAILABILITY