Looking into the “avoiding bit rot” sorts of stuff, and it looks like there’s a category of software that will go through a spinning hard drive and read/write each sector to update the magnetic signatures. DiskFresh being one example.
Has anybody actually used this type of software? And if so, is anybody aware of an app that does this on the Mac?
I realize this isn’t for modern Macs with SSDs - I’m looking to work with external, spinning drives.
I used to refresh drives and LTO tapes every couple of years by copying them. Copy drive/tape A to blank media, then overwrite drive/tape A with B and so on. Based on the time it takes to secure erase a drive I would guess that copying would be much faster.
As a computer tech, I’ve not heard of this before. What are the benefits of refreshing bits on an HD?
The claim goes like this:
Data written to a HD is done by creating a magnetic field. Over time, that magnetic field can degrade for a variety of reasons.
Rewriting the data on the hard drive (as long as it can still be read) “resets” the magnetic field, making it less vulnerable to problems.
As @webwalrus mentioned, all magnetic fields degrade over time. Exercising backup tapes was standard practice when I first became responsible for company data around 1992. As spinning drives became more common media for offsite storage many of us continued the practice we used with tape. At a minimum it was thought to help maintain the mechanical components of the drive.
I once had to restore data from a seven year old backup. And a few times after the data owner purged files that he “would never need again.” I always tried to err on the side of caution.
There’s no surer way to know there’s an emergency restore in your future than an executive declaring definitively that “we won’t need that data”. 