Aw: Re: rsync remote raw block device with --inplace

devzero at devzero at
Sun Dec 30 20:50:55 UTC 2018

> There have been addons to rsync in the past to do that but rsync really
> isn't the correct tool for the job.

why not correct tool ?

if rsync can greatly keep two large files in sync between source and destination
(using --inplace), why should it (generally spoken) not also be used to keep two 
blockdevices in sync ? 

maybe these links are interesting in that context:


> Gesendet: Sonntag, 30. Dezember 2018 um 19:53 Uhr
> Von: "Kevin Korb via rsync" <rsync at>
> An: rsync at
> Betreff: Re: rsync remote raw block device with --inplace
> There have been addons to rsync in the past to do that but rsync really
> isn't the correct tool for the job.  Neither is dd.
> The right tool is something that understands the filesystem within the
> block device such as ntfsclone (what I use) or partimage (if you have
> ever used Clonezilla this is what it uses).  These will know how to skip
> all the empty parts of the filesystem and will still be capable of
> restoring a complete image in a bare metal restore.  You can still use
> dd to snag a copy of the MBR since that is outside of any filesystems.
> Also, if you do have to resort to a plain image use ddrescue instead of
> dd.  It has a status screen and it can resume as long as you used a log
> file when you ran it.
> On 12/30/18 1:45 PM, Steve Newcomb via rsync wrote:
> > It would be very nice to be able to rsync the raw data content of, e.g.,
> > a non-mounted disk partition, particularly in combination with --inplace.
> > 
> > Our reality: several dual-boot machines running Windows during the day
> > and Linux at night, during backups.  Windows is very tedious and iffy to
> > re-reinstall without a raw disk image to start from.  Disks fail, and
> > the ensuing downtime must be minimized. 
> > 
> > We're using dd for this.  Most of the nightly work is redundant and
> > wasteful of elapsed time and storage.  Storage is cheap, but it's not
> > *that* cheap.  Elapsed time is priceless.
> > 
> > Rsync refuses to back up raw devices, and even raw character devices,
> > with the message "skipping non-regular file" (I think the relevant
> > message is in generator.c). 
> > 
> > In Linux, anyway, the "raw" command allows a block device to be bound as
> > a character device, and then even a "cat" command can read the raw data
> > of the block device.  So why does rsync refuse to copy such content, or
> > why is it a bad idea, or what rsync doctrine conflicts with it?  I agree
> > there are security concerns here, but rsync already disallows some of
> > its functions unless the super user is requesting them. 
> > 
> > 
> -- 
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