troubleshooting-hardware – Top 10 Data Recovery FAILS
October 11, 2020
I don’t know whether more recent tools have figured this out, but around 2003 this was a big problem, in my case with Norton Ghost 2003: never use a backup tool that compresses the backup data to reduce storage requirements. Any corruption on the medium containing the compressed backup may cause the decompression needed for recovery to fail.
In my case, I backed up a hard drive (I don’t remember what size) on either Win98 or2003, using Norton Ghost 2003. This produced a compressed backup of roughly 14Gb. When I went to restore it, the fourth of these was corrupted, and the restoration therefore failed at about the 25% mark.
What you really want is a backup format that adds data — duplicate blocks, checksum blocks, etc. — that makes it possible to reconstruct or pass over a corruption (notifying the user, of course, that a particular file had a problem, but/and the tool was (or was not) able to correct for it. if you see that kind of message you know to maje a fresh backup once you’ve finished restoring the old one).
At risk of dating myself, my go-to example is the BACKUP utility on VAX/VMS (later rechristened OpenVMS and implemented on other processors). That tool did what I’ve outlined above, and in 10 years of heavy use I never failed to recover anything 100%.
This topic helped me a lot when restoring data from an RAID array to one client. I also used RAID Recovery, this software was useful to me. I set up a backup for the future so that there are no unpleasant surprises.