what is a hard drive cache

Computers are very complicated machines that have all sorts of different pieces that have to work together for it to work properly. There is your CPU and GPU, your hard drive, memory, and many many other pieces that all have to communicate with each other seamlessly for you to have a good experience.

Most people know how big their hard drive is and how fast its read/write speeds are, but one thing that always seems to be overlooked by everyone is actually a very important detail that can drastically impact how fast your hard drive works. This little detail is the size of your hard drive cache. If you’re like most people you probably don’t know this spec on your PC and might not even know what it is or how it works. If that is you, keep reading.

What is a Hard Drive Cache?

You might not have heard of a hard drive cache, but you may have heard of the disk buffer. Even if you haven’t, that name might give you a hint as to what its purpose is. the cache acts as a temporary memory space for your hard drive while it reads and writes data to your permanent storage on the platters.

It is almost like RAM made only for your hard drive. Your hard drive has micro controllers built into it that control and process data that is going in and out of your hard drive. Almost like your CPU does. The cache and the controllers work together to store memory as your computer is processing it.

If that doesn’t make sense think of it like you are buffering a video and your connection isn’t very good. The video will take longer to load and may even pause before or during the playback because it is playing faster than it is collecting and process the video. The hard drive cache is what lets your hard drive do the same thing when reading and writing data.

How Does it Work?

When a hard drive reads and writes data it pulls the data from the platters. A lot of the time, the hard drive is pulling the same data over and over again. Most people only work on a couple things at a time, so they are pulling from the same data the whole time they are working on a task.

The drive will hold data that you or the programs you are using more than others and most recently in the cache which cuts the platters out of the equation for the data that is being access frequently and recently. It pulls from the cache to save time and speed up how fast the drive works.

Reading Ahead and Behind the Data

Most of the time a hard drive will read data from all around the data that is actually needed instead of just pulling one piece of data at a time. Hard drives are not efficient machines believe it or not.

The fact that hard drives use moving parts to complete tasks like the spinning platters and the read/write heads means that it has limitations that completely electronic ones do not. Because they are slower, they try to guess at what you are looking for by offering up the data you are looking for and everything closely related to it.

When you request data, the hard drive pulls the data needed and the data around it because it thinks that you will probably use similar data soon after. So, it stores the data and similar data in the cache to make things quicker later, or so it hopes. The cache is also used to smooth out all the processes being handled by regulating the speed at which data flows.

Wait Times When Writing Data

Like this whole article has been saying, hard drives are slow and are close to if not the slowest part of your computer. The cache helps speed up writing data by telling the rest of your computer that it is already done before it is. Instead of taking in data, writing it all, and then telling the rest of the computer it has done it, and the computer continues to send more data or moves on believing that the data has been written.

What this does is allow the rest of the computer to move on to the next task without waiting. The problem with this is that the hard drive can actually lose data while its lying saying it is already written. If your computer shuts down without warning, all the data that was in the cache right before will be lost.

Speeding Up Your Hard Drive

Having a hard drive cache doesn’t necessarily mean your drive will perform faster on individual tasks. It doesn’t speed of the parts inside your drive. But it does give your hard drive the ability to multitask which is actually very useful as you could have guessed. Hard drives very rarely, if ever, only do one thing at a time or interact with only one process at a time. Multiple programs or applications may need to access the storage at a time, and you could be accessing more than one file at a time as well.

Cache and SSDS

SSD is a nonvolatile storage media that stores persistent data on a solid-state flash memory, and they aren’t are slow as physical hard drives. So, would they need the use of a cache? The answer isn’t really straight forward and is closer to yes than no. Cache in an SSD is called DRAM which is like RAM but much faster and will keep up with the drive.

Even though the SSD is faster than physical drives it can still benefit from the use of a cache. Cache can help slightly improve read and write speeds and can help regulate the drives. Some of the SSD’s on the market don’t actually have this built in though.

Buying a New Drive?

As you read through the rest of this article, you have probably realized that cache does matter even if you didn’t realize it before. It may not be as important as the drives’ primary specs, but if your drive is going to be running constantly or multitasking a lot it can be a huge benefit to having a bigger cache.

If you are just a normal home user than this probably wont matter much to you. When it comes to solid state drives, you don’t necessarily need this, but it is still worth having a cache to help things along.