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

[Rolf Fokkens]

It was broucht up before indeed: 
https://lists.samba.org/archive/rsync/2012-June/027680.html

On 12/30/18 9:50 PM, devzero--- via rsync wrote:
>> 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:
>
> https://lists.samba.org/archive/rsync/2010-June/025164.html
>
> https://github.com/dop251/diskrsync
>
> roland
>
>> Gesendet: Sonntag, 30. Dezember 2018 um 19:53 Uhr
>> Von: "Kevin Korb via rsync" <rsync at lists.samba.org>
>> An: rsync at lists.samba.org
>> 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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>> 	Kevin Korb			Phone:    (407) 252-6853
>> 	Systems Administrator		Internet:
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>> ~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,
>>
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