Aw: Re: rsync doesn't checksum for local transfers?

[Kevin Korb]

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Correct.  If the disk fails to store the file correctly rsync will
have no idea.  This is the same as every other file copying program I
can think of.

On 12/04/2014 06:00 PM, devzero at web.de wrote:
>> You are missing the point of the checksum.  It is a verification
>> that the file was assembled on the target system correctly.  The
>> only post-transfer checksum that would make any sense locally
>> would be to make sure that the disk stored the file correctly
>> which would require a flushing of the cache and a re-reading of
>> the file.  Rsync has no capability to do this whether remote or
>> not.
> 
> yes, but indeed this could be explained more clearly in the
> manpage
> 
>>> """Note that rsync always verifies that each transferred file
>>> was correctly reconstructed on the receiving side by checking
>>> a whole-file checksum that is generated as the file is 
>>> transferred"""
> 
> let me try to add some lines :
> 
> After being written to disk, for both local and remote transfers,
> the destination file as a whole is not being re-read for
> checksumming. Checksumming is only being done for the
> reconstruction process: The checksum is calculated across the bits
> being received and the bits being read from the target file, so
> essentially the updated target file is being checksummed while it`s
> being written to.
> 
> is that correct ?
> 
>> 
>> On 12/03/2014 09:17 PM, Shriramana Sharma wrote:
>>> Hello. Please see http://unix.stackexchange.com/a/66702. I
>>> would like to have confirmation whether or not rsync verifies
>>> the transferred files' integrity at the target location by
>>> checksumming as advertised in the manpage:
>>> 
>>> """Note that rsync always verifies that each transferred file
>>> was correctly reconstructed on the receiving side by checking
>>> a whole-file checksum that is generated as the file is 
>>> transferred"""
>>> 
>>> The word "always" here seems to indicate that the integrity
>>> check will happen whether for local or network transfers, but
>>> the above Stack Exchange post claims otherwise. Please
>>> clarify.
>>> 
>>> Also, once it is assured that the check will happen *really* 
>>> "always", it would be useful to advertise the fact about the 
>>> integrity check in the website and description part of the
>>> manpage itself IMO.
>>> 
>>> FWIW I'm using rsync 3.1.1 (latest) on openSUSE Tumbleweed.
>>> 
>>> Thanks.
>>> 
>> 
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>> 
Kevin Korb			Phone:    (407) 252-6853
>> Systems Administrator		Internet: FutureQuest, Inc.
>> Kevin at FutureQuest.net  (work) Orlando, Florida
>> kmk at sanitarium.net (personal) Web page:
>> http://www.sanitarium.net/ PGP public key available on web site. 
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	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
	FutureQuest, Inc.		Kevin at FutureQuest.net  (work)
	Orlando, Florida		kmk at sanitarium.net (personal)
	Web page:			http://www.sanitarium.net/
	PGP public key available on web site.
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