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Hard drives come in many storage capacities, sizes, and speeds. There are many brands to choose from, and various features and specifications to go through.
As SSDs have taken over both the consumer and enterprise storage markets, hard drives have lost significant relevance as primary storage drives. However, people still use hard drives for various purposes. The most crucial benefit of hard drives is their lowest price per GB. For the same storage space in a hard drive, you may have to pay two to three times more for solid-state drives. High-performance drives may cost you even more.
If you’re looking to choose a hard drive for any purpose, here is a detailed buying guide to help you. I have already published a buying guide for SSDs, which you can check here.
1. Form Factor (Hard Drive Size)
There are two types of hard drive form factors in the consumer market. One is 2.5″ and the other one is 3.5″. The 3.5″ is a standard size for desktop computers and external drives. In this form factor, you get higher storage capacity because a single hard drive could have more than one magnetic platter. Also, the size of the platter is going to be big compared to the 2.5″.
The 2.5″ is a standard hard drive size for laptops and compact external hard drives. These are lighter in weight, portable, and often come in smaller storage capacities. The same form factor is utilized by the 2.5″ SSDs as well.
So, if you are buying a hard drive for your laptop to install internally, you generally get an option of 2.5″. However, for desktops, you can choose between 3.5″ and 2.5″ drives. Bigger form factors typically come with more noise, better performance, a higher price, and more storage space.
2. Capacity (Hard Drive Storage Space)
One of the best features of hard drives is their large capacities. You can easily obtain a 10TB or 20TB hard drive at any time. Although it depends on your specific requirements, you always have the advantage of having a single drive with multiple TB of data. A storage space of 500GB to 1TB is ideal for basic storage needs, such as documents and photos. 2TB to 4TB drives are suitable for storing large media files, games, etc. 6TB to 10TB or higher storage variants are more suitable for extensive storage like video files, databases, or NAS.
Lower storage capacity drives are generally more power-efficient, quieter, and less expensive. On the other hand, the higher storage variants provide you with sufficient space and peace of mind for future upgrades. There is nothing special you get with the different storage capacities.
Unlike SSDs, you get no special benefits with higher variants, such as higher TBW or better performance. It is your storage space requirements and budget that determine which capacity you choose. If you opt for a higher storage capacity, you simply pay more and receive nothing extra except the additional space.
3. RPM (Rotations Per Minute)
Hard drives store the data on magnetic platters. The bits are stored in the form of magnetic charge, where a difference in charge represents a bit. Therefore, the data storage and retrieval mechanism remains stationary (the read/write head moves in predetermined directions). To access any data block, the disks have to spin at a certain speed. A higher RPM generally means better read/performance, and vice versa. You can choose between 4 popular hard drive RPM options.
5,400 RPM
This is the slowest hard drive speed and is generally found in the smaller 2.5″ drives. The typical sequential read/write speed ranges between 80 and 100 MB/s. These drives are quiet, energy-efficient, and suitable for applications where high-speed data access is not required.
7,200 RPM
These hard drives provide the best balance of price and performance. They come with comparatively better performance but higher price tags. The typical sequential speed ranges between 100 and 150 MB/s. They come in both 2.5″ and 3.5″ form factors so that you can use them in almost any system.
10,000 RPM
There are much faster drives intended for high-performance systems and even workstations. However, they are expensive, and SSDs are competing pretty well with these. However, you can still get one for yourself,f and you can get the advantage of high storage space for sure.
15,000 RPM
These drives are designed for enterprise environments, servers, and other high-performance applications. The typical sequential read/write performance ranges between 200 and 300 MB/s. These drives are relatively rare because solid-state drives have largely replaced them.
So, all in all, you have two main RPM options: 5400 RPM and 7200 RPM. The 7200 RPM offers better performance but comes with a slightly higher price tag. 5400 RPM is suitable for basic tasks where performance isn’t a primary concern.
It is essential to note that, regardless of the RPM a hard drive can achieve, it can’t exceed 600MB/s in the consumer environment due to SATA-3 limitations. You can utilize caching for external drives to reach speeds of more than 600MB/s, but that is a topic for another day.
4. Cache Size
A cache is a small amount of buffer installed in your hard drive that serves as high-speed memory. Its basic task is to store the frequently accessed data by the operating system. Because hard drives have poor random performance, this cache alleviates the storage bottleneck during CPU operations.
The drive’s controller predicts the data that the system will require soon. So, it finds it and stores it in this cache. This primarily facilitates access to small files. These are the files that are generally utilized by the software and games that we run on our computers. It also reduces the latency and shows improvements during heavy workloads.
Small Cache (16MB – 32MB)
This amount of cache is sufficient if your hard drive’s primary purpose is to store raw data. Modern software requires much more than this amount of cache to work effectively. This small cache is suitable for basic tasks, such as web browsing, file storage, and light application usage.
Moderate Cache (64MB – 128MB)
This can be considered a pretty enough cache for light to average usage. You can consider using this drive as the primary OS drive if your workloads are low. This cache can serve you well if you want to do web browsing, file storage, light gaming, and other types of application usage.
Large Cache (128MB+)
I would recommend going for the higher amount of cache you can get. Having more of it would help you play games and do other demanding tasks on your computer. You can even do video editing and multitasking.
Again, you can’t compare this cache’s performance with SSD’s cache performance. This is because the CPU and RAMs are coming with tremendous read/write speeds. The hard drives can’t catch up with that. However, they are still compatible with the old systems if you can obtain sufficient cache for your software to operate.
5. Interface
For personal computers, you get the option to choose just the SATA drives in case of internal drives. You can still use external hard drives and connect them via USB, but we are referring only to internal drives.
SATA-3 is the top and most common interface for hard drives. Again, the maximum practical speed is limited to 600 MB/s. However, all SATA variants are forward and backward compatible. But you will hardly find SATA-1 or two drives in 2025.
For enterprise hard drives, the most popular interface is the SAS. These are much more expensive drives and require specialized hardware that can be set up in enterprise environments.
6. Reliability and Durability
For hard drives, you can check and compare the load/unload cycles, power-on hours per year, TB/year, and warranty period. These are the things that would determine your drive’s reliability. Some drives can also come with the MTBF (Mean Time Between Failures) numbers. It is advisable to opt for drives with an MTBF of over 1 million hours.
7. Purpose-Specific Features
When looking for hard drives, you will see drives designed for specific purposes such as NAS drives, Surveillance drives, and enterprise drives. These drives are specifically designed for these purposes, and it is best not to use them for other tasks.
For example, the NAS drives are designed to operate 24 hours a day and are priced accordingly. You should not waste your money on this drive by installing it on your personal computer.
Similarly, the surveillance drive is designed by manufacturers for high write operations with improved reliability. The enterprise drives are again made for higher reliability and performance. Therefore, if you are selecting a hard drive for a specific purpose, ensure that you choose a hard drive specifically designed for that task.
8. Price vs. Performance vs. Usage
It is always good to look for the drives that offer the best value for your money. Hard drives aren’t costly. So, don’t go for those fancy features if you don’t need them. There are performance drives that will cost you, but checking that they are enough for you is essential. Modern systems are high-speed and require exceptionally high data read/write speeds to operate optimally.
For continuous operation drives, you’ll have to pay more because they are specifically designed for these tasks. Do not attempt to save money by trying to extend the drive’s lifespan beyond 24 hours, as this may cause damage and result in permanent data loss.
Hard drives are now primarily used for storing raw data. So, if you plan to dump your data in it and keep it aside, it is better to go for drives with higher storage capacity to save space.
You will generally see drives marketed as high-performance drives, but they may not be ideal for use as the primary operating system drive in your computer. It is always better to use an SSD for that purpose. You can opt for a smaller SSD and use a larger hard drive for raw data storage.
9. Brand and Reviews
There are many brands in the market offering their hard drives in different capacities, speeds, and for various specific tasks, as we discussed above. Ensure you opt for a reputable brand and read reviews before making your purchase.
10. Environmental Considerations
Lower-RPM drives tend to be quieter and more power-efficient. These are good for home and office environments. If your drive is going to be running 24/7, consider getting a drive with better energy efficiency. A significant advantage of hard drives is that they generate relatively little heat. However, if you are combining multiple drives for a database environment, RAID, or NAS, you may still need to set up a cooling mechanism.
In modern systems, hard drives are used for backup and raw data storage (typically to store big files) because of their cheap storage price. They offer poor performance compared to SSDs, but they are still effective for bulk data storage. This might be the reason why they are still available in the consumer market.
With this buying guide, I hope you will be able to pick the best hard drive for your system.
11. CMR vs SMR Hard Drives
Conclusion
Choosing a hard drive is easy compared to an SSD. It primarily involves selecting the appropriate capacity and size. CMR and SMR can be other considerations, but CMR has largely dominated the market. You’ll find very few SMR drives out there. Other factors to consider include warranty, RPM, brand, and reviews. You can buy the right hard drive for your system.
