SSHD hybrid discs - what kind of bird?

In our work, we often have to deal with a variety of storage media, including hard drives and solid-state storage drives. At the same time, quite unusual devices are sometimes found that are not common everywhere. For example, SSHD - hybrid hard drives. Probably, there are people on Habré who are well acquainted with this type of information storage, but there are also those who have not even heard of such “hybrids”.

Therefore, we decided to publish an article about such hard drives, describing their device, as well as advantages, compared with the usual hard drives and SSD.
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So, hybrid hard drives, first of all - a compromise solution that allows both to increase the overall performance of the system in which they are installed, and reduce the price of such a system.

Indeed, despite the widespread occurrence, solid-state drives are still quite expensive, and it is unlikely that a moment will soon come when the price of such drives will drop significantly.

Regular hard drives are inexpensive, for the most part, but their performance is limited, it is impossible to “jump” above a certain limit. Therefore, hybrid hard drives appeared. SSHD appeared a few years ago, and at first they were pure exotic, which few people took seriously (and very few people knew about them). The main advantage of a hybrid hard disk is to increase the overall performance of the system in which they are installed, using only one disk bay (and not two, if you use both an SSD and a regular hard disk). Now there are models of “hybrids” of small sizes, for example, with a thickness of only 7 mm (this is exactly the model of the ST500LM000 from Seagate), which allows you to install such disks in netbooks / ultrabooks.



The principle of operation of SSHD is based on caching the most frequently used data using flash memory, that is, the SSD part of the “hybrid”. Already when the operating system is first launched on a laptop / PC with a “hybrid”, the files that the operating system needs to load are placed in the non-volatile part of the SSHD memory. As a result, the OS startup speed increases, and quite significantly.

The hybrid disk, by the way, shows almost similar results of the file transfer speed compared to conventional hard drives. But the difference in the operation of different types of devices becomes very noticeable when comparing the access time to files (Access Time). For example, if you take a 500 GB Seagate ST500LT032 drive and compare it with a similar capacity ST500LM000 hybrid, the access speed to files will be 24.2 and 0.3 ms.

As for the speed limit of the interface, the difference is no longer at times, but 15%. In the first case, 101 MB / s, in the second - 115 MB / s.

There are drawbacks too, and first of all, it’s the inability to fit all the critical data on the SSD part of an SSHD disk. Usually, the SSD in the "hybrid" is set to 8 GB, sometimes more (for example, models with 32 GB of flash memory are not uncommon), but then such a drive will be more expensive.

At the price of "hybrids" only slightly higher than the price of conventional hard drives. If you take the models already mentioned above, the price of the Seagate Laptop Thin SSHD ST500LM000 is $ 73-75, and the Seagate ST500LT032 is about $ 50.

So, if you want to increase the speed of loading the OS, as well as the overall performance of your laptop / desktop PC, we recommend using "hybrids". Well, this is if saving is important to you. If not, then you should use the SSD and the usual hard drives separately.