How does SSHD

SSHD - Solid-State Hybrid Drives

Solid-State Hybrid Drives, or SSHDs for short, are hybrid hard drives that consist of a conventional hard drive with additional flash memory. The flash memory serves as a data buffer for read and write access and is intended to ensure shorter access times. In the flash memory, the hard disk controller often also saves data read from the magnetic disks so that they can be read from there at SSD speed. At the same time, write processes with a small amount of data are written to the flash memory and later in one piece on the magnetic disks. This saves electricity because the magnetic disks in the hard disk have to start up less often.

In summary, it can be said that this method reduces the power consumption of hard drives and increases the read and write speed. The bigger the flash memory, the better it works. It is conceivable that a computer boots from the flash cache or wakes up from hibernation. A computer could be up and running in less than a second.

Hybrid hard drives work around 20% faster when reading and writing, but this only increases system performance by around 10%. Note: As a rule, the user hardly notices speed increases of less than 20%. As a rule, the use of hybrid hard drives is not worthwhile.

Structure and functionality of a hybrid hard drive


Part of the flash memory is used to buffer write accesses. Instead of writing the data to the hybrid hard drive straight away, the data is stored in the flash memory. The memory is written to until it is full. During this time, the drive remains in power-saving mode. Only when the flash memory is full is the drive woken up and the contents of the flash memory transferred to the magnetic memory.
In this way, the flash memory accelerates write access. Especially the non-linear accesses, in which the read / write head of the hard disk moves several times over the disk. This is very time consuming. When writing to the flash memory, the mechanical processes are initially eliminated.
Speed ‚Äč‚Äčadvantages can also arise during the reading process.
Hybrid hard drives are particularly interesting in notebooks. Here, low power consumption and fast start-up times are important. There is a special ATA command with which a hybrid hard disk can be instructed to use the flash memory to save power. The drive is put to sleep as often as possible and all write access is first stored in the flash memory.

In the case of hybrid hard disks with a flash memory of only 8 GB, only a few accesses can of course be accelerated. And that only works if the self-learning controllers identify these accesses as a buffer value. And for this, the data on the magnetic disks must be buffered in parallel in the flash memory. With a small flash memory, only regularly used applications are accelerated.

Hybrid Information Protocol

It is a serial ATA protocol extension with which the flash memory can be managed by the operating system. The operating system then decides what is stored in the flash memory.
Operating systems can address the flash cache of hybrid disks via an appropriate driver and store data there in a targeted manner. For example, to fill the cache with data in advance, which enables a higher reading speed.

Overview: hard drives

Overview: interfaces for hard drives

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Everything you need to know about computer technology.

Computer technology primer

The computer technology primer is a book about the basics of computer technology, processor technology, semiconductor memory, interfaces, data storage devices, drives and important hardware components.

I want that!