Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Block devices synchronization tool
branch: master
Failed to load latest commit information.
.gitignore Add README
COPYING Initial commit.
Makefile Amend clean target Clarify motivation
bdrsync.c Do not state the obvious


This Linux-specific tool efficiently copies contents of one block device to another, by reading devices block-by-block and only writing to second device blocks with non-matching content.

It is more efficient than plain dd(1) if the following conditions are met:

  • infrequent writes to the second device do not ruin speed of linear read,
  • second device write speed is way slower than read speed.

Otherwise don't bother, and just use dd(1).

Note: this tool does not do any locking or thawing of filesystems, so copy might not be an exact snapshot of source device at any moment of time. IOW, use it with caution, during low-activity time, and on journalled filesystems.


Implementation of JWZ backups scheme for laptop with complex structure of LVM volumes and USB-attached hard drive.

License and Copyright


© 2009-2011 Mikhail Gusarov

Something went wrong with that request. Please try again.