In my spare time, I like to make music, and I have some high powered speaker monitors on my desk… I was looking at them thinking about the magnets inside when it occurred to me maybe I should move the stack of hard drives on my desk away a little bit! It begs the question could a magnet destroy a hard drive?
When it comes to SSD’s the answer is that a magnet big enough that you wouldn’t want to be near it might do the trick. However HDD’s are a little more sensitive, your speakers or other household magnets will have little effect on them but a powerful magnet left in the wrong place could cause trouble for your disks.
There are a few things to consider when it comes to magnets around your hard drives and computer equipment so lets look at the things we should be worrying about.
What effects do magnets have on an SSD?
Solid State Drives use flash RAM as the storage element, which in and of itself is not a magnetic storage medium. Where most of the later analogue and early digital data storage devices used some form of magnetic medium to code the data, (i.e. Tape cassettes, DV, and HDDs) flash memory stores data using electrical charges on an EEPROM chip, this stands for Electronically Erasable Programmable Read Only Memory. It uses a grid of cells with two transistors at each intersection called the floating gate and the control gate. The cell has a value of 1 or 0 depending on whether these two transistors are linked. This is done via a process called Fowler-Nordheim tunnelling.
Essentially what this means is that magnetism by itself cant alter the state of the cells. But can it damage or corrupt the data or components in other ways?
Magnets and electricity interact and have direct effects on one another, we are surrounded by electromagnetic waves all the time, light itself is an electromagnetic wave. We are interested in one particular interaction and that is induction.
Essentially when a conductor has current running through it a second conductor placed within the magnetic field of the 1st can produce current. This is essentially how your wireless phone charger works. A static magnet won’t affect an SSD. The key here is the fact that for a magnet to create induction the polarity has to be changing, which means the magnet has to be moving and even then it is highly unlikely that magnets found in your home would have enough power to do anything at all.
What effects do magnets have on HDDs?
HDDs are far more susceptible to corruption from magnets, but it should be pointed out that this is still relative, it is not likely any magnets found in your home will have any impact on an HDD.
The disks inside an HDD are coated in a ferromagnetic layer which can be written into different states, these states are used to code the data that needs to be stored. The disks spin and a movable head reads the data like a tiny jukebox. Electric motors contain magnets so it is worth pointing out that magnets themselves are a component of Hard Drives which indicates that the disks are well protected from outside influences. They have to be considering the external influences they are likely to come up against, like magnetism, heat, cold, humidity etc…
So let’s take ourselves out of the average environment and consider some other situations where a stronger magnet might come into contact with a hard drive. I’m not sure what these are but let’s imagine you have a rare earth magnet on your desk, under a bit of paperwork and while looking for a file stored on a hard drive one of your hard drives you place an already searched disk on the pile of papers while you check the next one…
Now we have a significant amount of magnetism running through the disk, but the disks arent spinning. Even in this circumstance an average magnet is unlikely to have too much impact as the ferromagnetic layer is protected and usually have a specified operating tolerance of 1 mT of magnetic field intensity at the drive’s perimeter. A rare-earth magnet could increase the intensity to up to 100mT which would take the components way outside of specified tolerances and this is where the trouble begins. Depending on the hard drive at this point odd things could start happening. ‘Could’ being the keyword.
Now let’s say you think… oh wait the file I wanted was on that disk! and you plug it back in while it’s over the magnet. This is where you are likely to see problems arise with the disk and people have even reported that the servo markers were getting deleted rendering the hard drive completely unusable. There was even a period in the 90s when people’s laptops were getting corrupted disks while using them on trains in Germany which had strong magnets in the folding tables.
How does electromagnetism effect hard drives?
As I said before magnets and electricity interact, we use this interaction daily in motors and induction coils all around the home. We have established that Magnets themselves are unlikely to affect hard drives but what about electromagnetism? Induction is the likely candidate for causing damage and it is only likely to damage a hard drive, SSD or HDD if it has a specific interaction it. I have looked all around myhouse for any devices that have the ability to create induction. I have found my induction hob, my rice cooker, the PSU in my PC, but there is only one that I think could possibly come into contact with a hard drive and that is my wireless phone charger.
This is about the only situation I can envisage a hard drive coming into contact with an induction device, unless you tried to cook it on your hob.
Let’s set the scene. you have a lovely clean minimal desk (come on, I’m sure you do.). On the desk is a laptop, a wireless charger for your phone and that is all. You select an HDD from your draw and place it on your desk, about 5 inches away from the wireless charger… What happens?
Nothing. Inductive chargers are only effective up to a maximum distance of about 1 inch and even then they would need to line up, you may have noticed you need to find that sweet spot to get your phone to start charging. This is why… you are lining up the coils.
Ok, so far so good but maybe you go on holiday for 2 weeks and leave the desk as is. What happens?
Nothing. Time is basically irrelevant in this scenario, if there is nowhere near enough induction to have an effect it won’t have an effect, it isn’t cumulative until it’s powerful enough.
Ok, now let’s say during the holiday the cleaner comes in (Come on, I’m sure you have a cleaner.) and they see a hard drive left in the middle of your otherwise spotless desk (You don’t really need a cleaner do you.). So they pick it up and place it on the wireless charger thinking it is obviously a hard drive stand. What happens?
Nothing. Probably. Most wireless charger manufacturers have to meet safety and energy requirements and have a ‘communications and control’ unit to regulate the power which means that when a wireless charger isn’t actually charging something it puts out very low currents, only enough to detect a chargeable device and will output the required amount of current. Seeings as a hard drive isn’t chargeable and doesn’t contain a coil the ‘communications and control’ unit simply wouldn’t detect the hard drive and wouldn’t increase the power output. (So luckily you don’t have to fire your cleaner. )
Should I be worried about Magnets around my hard drives?
In conclusion, I would say that this is not something to consider in most situations. Unless you have some very strong magnets laying about but even then you are probably the sort of person who knows just what they can do and how to keep them away from electronics! It is highly unlikely that you would have a strong enough magnet within range of a hard drive to do any real damage and even then it would require pretty unique circumstances.
So rest easy, your speakers or your wireless charger will have no effect on your HDDs or SSDs but that doesn’t mean you shouldn’t keep them safe and always make a backup!!