In the past, SSD don't have cache, but now most SSD capacity up to 128GB will build an 128MB cache, but what the cache use for and why we need it?
Now let's take a close look at SSD Cache performance, comparing it directly to using a dedicated SSD drive for Windows, applications and gaming installs. Ask anyone who has an SSD installed in their system, and they will tell you that it gave them the most noticeable performance boost over any hardware upgrade they’ve ever done (with the exception of video cards).
While CPUs have increased in speed, cores, and efficiency, and we can install huge amounts of ram in a system running upwards of eight channels, if the data you are loading is still coming off spinning platters read by a moving head, there is always going to be a delay in getting that data to you. While read latencies occur in the CPU cache and memory in nanoseconds, mechanical hard drives are in the 5-10 millisecond range. That is a lifetime in comparison. SSDs are in between – they are in the 30 microsecond range (or 0.03 milliseconds). This is what makes the performance boost so noticeable, and why a system with an SSD in it always feels more ‘snappy’. Additionally, the 4K I/O per second performance and data transfer speeds are dramatically higher than on a mechanical HDD. This leads to better load times in applications and games.
But there is still one major problem with SSDs today – price. If you look at your Windows and “Program Files” directories, you are probably using at least 300-500 GB of space if you have a few games installed (this is not taking into consideration storage of media like videos, photos, and music) or at least 100-200GB if you primarily have office applications installed. At that level, you are looking at an expense of at least $400 for an SSD big enough to hold all that data. Alternatively, a middle range 512GB mechanical drive is around $60-70.
Some people get around this by installing a smaller SSD as a “Windows Drive” and using a mechanical drive to install their applications on. You can grab a 128GB version of any SSD for around $100, which brings down the cost considerably. The problem with this is, you only really benefit from half of what SSDs have to offer. Your system will definitely feel more ‘snappy’ overall, with boot times drastically reduced. And perhaps you can install a few of your most used programs on it before running into capacity issues. But if you are running most of your programs and games from a mechanical hard drive, you are really missing out on the data transfer performance SSDs have to offer.
That is where SSD caching comes in.
By combining a smaller $100 with any mechanical drive, you should be able to benefit from the SSD’s performance gains without worrying about capacity. Ideally, the data that gets used the most will reside on the SSD, while the rest resides on the mechanical drive. The less a program gets used, the less of a chance it has at being moved to the SSD, overwriting more important programs. If this works well, then you will never have to worry about moving programs around between an SSD and HDD, and you can be sure that you are almost always getting the best performance possible, and the SSD is not being ‘wasted’. By the end of this review, we’ll know for sure of SSD caching is as good as a dedicated SSD, and whether it’s the best way to make use of a smaller, cheaper SSD.
If you have old SSD with no cache at hand, here is some tips to set up cache from motherboard. If you have a Intel motherboard, such as a Z68 or Z77 (but NOT X79, disappointingly), you already have caching capabilities. Dubbed Smart Response Technology, all you have to do is set it up within Windows – any SSD can be used, and the cache can be as large as 64GB. The leftover space can be used as a partition, or left empty to allow for higher over-provisioning (this is recommended for best performance).
If you are not using an Intel platform, another option is to use a dedicated cache drive such as the Crucial Adrenaline or OCZ Synapse. These work much like standard SSDs (in these cases, they are equivalent to a Crucial m4 or OCZ Agility 3 respectively, and have extra over-provisioning built in) but come with caching software that works with any motherboard.
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