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how to validate data integrity on a backup HDD?

T

telimar

n00b
Joined
Sep 19, 2009
Messages
54
hi

I weekly backup my data on an external HDD.
how can I be sure that the data copied to that external HDD is not corrupted or invalid or "broken" in some other way?

it's not like it's one or two files that I can just see if they works, there are tons of files...so I don't know who to check.
 
This is good on Windows:
http://corz.org/windows/software/checksum/


Similarly there is a command line took, cfv, that is good on Linux, although its also available for Windows its only commandline and more of a pain to use.

If you use the cozr checksum program when you first use it pick like recursive and one hash file in root directory.

So if you have like a folder "SuperImportantStuff" you right click on it, do 'create checksums'


Then you do your backup software, and the on backup media right click on it and do 'verify' and it'll check hashes.

Ideally your backup software could verify data as well, but I guess this would be good enough if it doesn't.
 
You can make a parity archive of your source volume and then verify the backup volume against it. QuickPar includes everything you need, is free and if you make a parity archive set can even fix bad/missing items in the destination
 
Be aware though that a thorough verify will take a fair bit of time, especially on a large full disk.
 
Greetings

A simple comparison utility you could use to compare a source with a target directory would be windiff which you can download as part of the XP SP2 support tools, see the link provided here

http://en.wikipedia.org/wiki/WinDiff

A more sophisticated way of doing this and also fixing/repairing any errors on the target directory would be to use rsync

http://en.wikipedia.org/wiki/Rsync

However, as you are more likely to be copying from say an NTFS internal hdd to an external NTFS hdd it is probably just as likely that an error such as an URE/bad block could occur in your internal hdd, ultimately you would probably want to backup your data on a ZFS server as once there you can take advantage of (1) automatic check-summing of each and every block (2) using parity raid drives for protection against failed hard drives and bad blocks and (3) using snapshots on a regular basis, the advantage of snapshots is that say some virus such as ransomware corrupts some files you can easily find affected files by comparing the current backup files with the ones in the snapshot images as snapshots are read only.

Cheers
 
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