SSDs are NOT HDDs: Important things to know about this common new storage medium

You’ve all heard of solid state drives, or SSDs, the new performance-enhancing addition to modern computers. They’re “supercharged” versions of traditional hard disk drives (HDDs) which are built on spinning disk technology. Compared to HDDs, SSDs run faster, use less power, generate less heat, and have no moving parts. That’s great for laptops, or anyone who wants 4x faster “hard drive” access for super fast boot times. SSDs aren’t without their faults, though. They cost more than hard drives and usually have less storage space. They also put your data at risk in ways very different from the hard drives we all have come to know over the last thirty years.

There are several ways SSDs differ significantly vs Hard Drives.

1. They have a limited lifetime of writes. While magnetic disks basically can have data written, erased, and written again indefinitely – till bearings seize up or they get dropped or the like, SSDs have a specific amount of write cycles they can take. Every time you write to an SSD, that decrements the number of additional writes they can take. Once you hit a certain level, many drives will refuse to work properly – being in a “disaster read only mode” till you reboot, and then refusing to power on at all. Modern SSDs in 2015 have this limit, but they are usually around 1 petabyte (1015 bytes) of data writes. This is A LOT on a common 256GB drive.

So what does this mean? Well, you’re likely to replace an SSD (when getting a new PC, or replacing the SSD with a drive that has more space, eg) before writing a petabyte to it. There are some kinds of use that could hit this limit though – specifically if you use programs that create a lot of temporary files all the time. The other is if you move files around the disk a lot – one reason Disk Defragmenters need to be SSD aware if you’re using one.

2. SSDs can’t be put on a shelf for storage. Normal HDDs, while not an archival medium, will usually sit on a shelf for a year or two, and be perfectly fine when you plug them back in – and anything you stored on them is still accessible. It’s common for people to save their old HDD for a bit after getting a new computer in case they forgot to copy anything over. SSDs don’t work that way. They need to be powered on to store data. While they will persist over a reboot, or a trip, they aren’t meant to be put on a shelf for a year and then looked at. Many SSDs will start losing data in as little as 3 months when disconnected from power. After a year, you’ll notice missing data, and may not be able to read the drive at all without re-formatting it…

3. No-Warning Failure modes. HDDs can fail catastrophically with no warning – pretty much any electronic device can. But that is rare, barring external trauma. Most HDDs start making noises, alert the computer via SMART or Windows notices, begin to “slow down” and other things that can give you a heads up that there’s something going wrong. If they fail, you can sometimes use tricks like freezing the HDD to bring it back long enough to copy files off. SSDs don’t work this way. They’re more like USB Flash Disks – they work one minute, you reboot and nothing. SSDs don’t make noises, there’s not a lot of software that can test or notice that an SSD is starting to fail, and the internal controllers, as stated above, err on the side of intentionally failing to even talk to the computer vs potentially having some missing data.


Final takea-aways: SSDs are great when used properly, but you can’t treat them like HDDs. You’ll want to have backups even more than with normal HDDs because when they fail, it’s sudden, and they all WILL fail. There aren’t likely to be 10 year old SSDs just chugging along like some HDDs. You might want a spare spinning disk for your bulk storage and backups. You might want a spare SSD for a quick recovery when the SSD does die.

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