Does rsync detect file corruption?

Mac User FR macuserfr at free.fr
Sun May 24 14:04:44 GMT 2009


A simple way to prevent this is to store the backup with a rotating  
system and hard-linking files.
You can do it with rsync --link-dest=DIR option and a post-exec script  
that moves the backup dir to something like backup-200905241335

In this way if the file got corrupted it won't be hard-linked and you  
will have a safe copy from a previous backup. Hard-linking an  
unchanged dir takes very few place.

Best regards,

Vitorio

Le 24 mai 09 à 15:05, Christian Hecht a écrit :

> This will safe you if your file is corrupted on the backup side.  
> Rsync will copy it then again from the source because the checksum  
> is different and everything is okay.
>
> But imagine the file is corrupted on the source side. Then rsync  
> will copy the corrupted file again and if you delete older backups,  
> at any time your backup is corrupted too.
>
> Someone pointed me to this case a few weeks ago, so i started  
> thinking how to avoid this.
>
> I will try to write a tool which stores the rsync checksums ore  
> generate own checksums for each source file.
> Then, at any time the stored checksums can be compared with the  
> source files.
>
> Best regards
> Christian
>
> Am 22.05.2009 um 16:22 schrieb Daniel Carrera:
>
>> Matthias Schniedermeyer wrote:
>>> Exactly.
>>> But you can (periodically) add "-c", then rsync while checksum the  
>>> whole content of all files.
>>
>> Thanks. I'll add a -c for the Saturday backup.
>>
>>> But IF you have (or suspect) such type of corrution, you have have  
>>> an even greater problem: Your hardware is crap.
>>
>> Yeah. I hope I don't have that particular problem. But I want to be  
>> prepared if it happens.
>>
>> Daniel.
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