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 the blocksize in bytes. This size does not describe
device topology. It’s the size used internally by the kernel and it may
be 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 as --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, a 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.