How does rsync file verification work?

Kevin Korb kmk at
Sat Feb 4 21:27:00 MST 2012

Hash: SHA1

Frankly, rsync -c (--checksum) is almost always an entirely horrible
idea.  If you absolutely insist on either using rsync to determine
what is corrupt or want to ensure that only absolute minimal data is
transmitted (--only-write-batch) it is MUCH faster to simply re-delta
copy everything using --ignore-times.

On 02/04/12 23:22, Jason Haar wrote:
> On 05/02/12 06:01, Kevin Korb wrote:
>> Rsync does not verify the data after it is written to the disk.
>> The whole file checksum is only done to ensure that the file
>> crossed the network intact.
> Actually rsync doesn't checksum by default - if a file has the
> correct date and size it's assumed to be the same file.
> To achieve the goal, you could run a "rsync -az" type of thing to
> do the initial sync, followed by a "rsync -c ..." to manually check
> each file is the exact same file. This will of course make the
> entire process at least twice as slow - but it will ensure you have
> confirmed the copy is precisely what it says it is (I am ignoring
> filesystem/hardware caching of course)

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