Since this is “general” discussion and related to data integrity I was wondering if anyone had any insight into this oddity I run into occasionally at work.
The setup involved here is:
- Mac Pro
-> G-SPEED esPro (mini-SAS)
-> three DroboPro’s daisy-chained in FW800
- Fujitsu Eternus backup server (volume mounted via smb)
Whenever a video is completed here, I copy it to both a DroboPro and the Fujitsu Eternus so I have two RAID-6 copies. I also run md5 hashes on them to verify they copied correctly.
On occasion, like this morning I’ll get a result like this:
md5 (Mac Pro local drive): value 12
md5 (DroboPro): value 13
md5 (Fujitsu): value 13
So the md5 hashes don’t match after the file is copied, but they’re identical on both the DroboPro and Fujitsu. Then I re-copy them, and run md5 from Terminal again and they’re all the correct value (in this simplified case, 12).
Isn’t that odd? I can understand a copy going bad because of some network issues or something, but how can the two bad copies have identical md5 hashes to one another?
Also, does anyone know of a good OS X program with a GUI to run batch checksums like this? There was a program I used years ago called “zsCompare,” but that company seems to be long out of business and there’s no way to get their software anymore.