The original post: /r/datahoarder by /u/Positive_Minds on 2024-06-13 12:32:48.
This 4TB drive and also my 10 year old 2TB HGST drive. have popped up bad and weak sectors , they haven’t been switched on in 10 years ..
So was this basically my fault for not powering them up every and using disk fresh etc or is it just a case of age related demagnetisation or mechanical failure ? I just don’t get as most of my 10 year old western digital drives or seagate have been fine when tested after 10 years
I’m seriously thinking of doing yearly refreshes of my drives from now on .. My other question is can the weak sectors be reallocated or removed ?
I read this on super user , is this true ?
In order to keep the data signal from fading, you need to re-write the data. This is often known as “hard disk maintenance”, and should be done 3 or 4 times a year. While it does not prevent data from being corrupted or deleted, it can go a long way towards ensuring that the magnetic signal does not fade away completely. The way it works is to read every sector of the drive, and then re-write the data found there, provided the drive reported no errors. If this is done on a regular basis, the magnetic signal of every part of the drive will be refreshed long before the signal fades or becomes ambiguous. This technique also gives the drive controller the opportunity to decide whether to retire any sectors that are becoming too unreliable, before any important data is lost.
Magnetic Field Breakdown
Most sources state that permanent magnets lose their magnetic field strength at a rate of 1% per year. Assuming this is valid, after ~69 years, we can assume that half of the sectors in a hard drive would be corrupted (since they all lost half of their strength by this time). Obviously, this is quite a long time, but this risk is easily mitigated - simply re-write the data to the drive. How frequently you need to do this depends on the following two issues (I also go over this in my conclusion).
To periodically refresh the data on the drive, simply transfer it to another location, and re-writing it back to the drive. That way, the magnetic domains in the physical disk surface will be renewed with their original strength (because you just re-wrote the files back to the disk). If you're concerned about filesystem corruption, you can also format the disk before transferring the data back.
You can also help to avoid this issue by archiving your data with recovery data and error correction when you put the data onto the drive. Many archive formats support the inclusion of data recovery algorithms, so even if you have a few corrupted sectors, you can still re-build the lost data.
Depending on the priority of the data you've stored, you may want to refresh the hard disk more often. If it is essential data, I would recommend no less then 2 years at maximum. If you can withstand some chance of minor data loss (e.g. a few corrupted sectors here and there), go with 5 years. It doesn't take long to copy the data off the drive, and copy it back.
One thing not considered is the servo tracks and markings. These are written one time at the factory and never again (on modern disks). No amount of re-writes by the user or so-called low-level formatting freshens these. Once they fade, they fade!
It's different with the first stepper motor disks of the 80's. They don't have servo tracks and a low-level format writes ALL of the bits - fresh.