SSD Cache Performance – Is it as Good as a Dedicated SSD?


Today we’re going to 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).

SSD Cache Performance

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.

There are a few ways to set up an SSD cache. If you have a modern 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. In our experience with these products, they perform almost identical to Intel Smart Response.

Other options include Hybrid hard drives and other hardware solutions, but we’ll only be looking at the easiest/cheapest method today.

So let’s set up an SSD cache, and see if it really is the best way to use a 128GB SSD!

Test Setup

We won’t be running our usual low-level data transfer tests, as that would be pointless. Once data is cached, it will run on the SSD, and that’s all that matters. What we want to find out is whether programs are cached to the SSD efficiently enough to be useful, and what kind of real world performance benefit this provides. So for this article, all our tests will be on real world applications.

Tests were run on the SSD by itself, the HDD by itself, and the HDD and SSD set up as a Smart Response Technology cache using Intel’s RST software. I’ll tell you now that going back installing Windows and benchmarking on a mechanical hard drive after using nothing but SSDs for years is excruciatingly slow. So there’s my subjective anecdote for the article 🙂

It should be noted that until data is actually cached on the SSD, it will run from the mechanical drive. If we were to pre-cache all the software, the test results would be skewed. In order to replicate a realistic testing environment, I installed Windows and all the test software on the mechanical drive, then installed the cache as a user normally would.

First let’s look at some quick ‘instant gratification’ results. Will SSD caching affect file copy speeds? How about installing new programs and booting Windows?

File Copy Test

To test file copy performance, we will copy a 22GB Steam installation directory from a Samsung 830 Series SSD to each drive setup. This will tell us how real world write speeds are affected. If SSD caching is being utilized properly, it will score about the same as a dedicated SSD:

SSD Cache Performance in File Copy

There you have it, copying a file from another drive to a cached drive is about the same as copying to a dedicated SSD. From here, the software will continue copying the files to the mechanical drive, allowing the data to be overwritten with more important data.

Program Installation

Next we’ll install a program from the same SSD to each drive setup. This should be similar to a straight file copy. We are using Photoshop CS6 as an example here:

SSD Cache Performance in installing Photoshop CS6

Once again, the cache is allowing us to install to the drive at the speed of an SSD. As you can see, it makes a huge difference, cutting the time by over half.

Windows Boot Time

Everyone knows that the most noticeable performance improvement an SSD can give you is Windows boot time. While mechanical drives take over a minute to load Windows, an SSD can do it in under 10 seconds – this is the first thing most SSD users notice after they install their new drive. But what if you are using a cached drive?

SSD Cache Performance in Windows Boot Time

Once the system is rebooted for the first time, Window’s important files are sent to the cache, and the cache partition works just like an SSD.

Next we’ll go to work, and see how a cached drive performs in real world office applications:

SSD Cache & SYSMark 2012

SYSMark 2012 is the perfect application to test SSD cache performance in office applications. Since it runs pre-programmed tasks through real world applications in real time, it will allow any improvements had by increased program and data load times to be reflected in the scores.

Final scores are given, and this time we did not do a ‘conditioning run’ which would have allowed most of the data be pre-loaded into the cache drive, which would skew results a bit. Instead, we took the mean of three runs of each test. This gives us an idea of the overall performance of an SSD cache drive after it has been in use for some time.

It should be noted now that even a small point increase in score is quite significant, since this is not a storage test, but an overall system performance test. We will be skipping the suites that are purely CPU limited rather than storage performance limited (3D modeling, Media Encoding)

Office Productivity

Read, create and search for emails. Create and execute a rule on email inbox. Use multiple browsers to browse a blog, online shopping site, wiki site and social networking site. Check web mail in a private browser session. Combine multiple scanned pages from a complex document into an encrypted PDF document using optical character recognition (OCR). Create a PDF with fillable form fields from scanned pages. Archive a diverse set of files into an a single encrypted file. Use an advanced OCR program to convert scanned pages of complex and simple documents into editable word documents. Create a blog post and do a mail merge. Use a spreadsheet program to do data analysis. Create and view complex presentations that include clip art and video. Some of these activities are performed concurrently to model typical multitasking behavior.

Programs used:

  • ABBYY FineReader Pro 10
  • Adobe Acrobat Pro 9
  • Adobe Flash Player 10.1
  • Microsoft Excel 2010
  • Microsoft Internet Explorer 8
  • Microsoft Outlook 2010
  • Microsoft PowerPoint 2010
  • Microsoft Word 2010
  • Mozilla Firefox 3.6.8
  • WinZip Pro 14.5

SSD cache performance in Office Productivity

Because so many common tasks are done in this suite, this is probably the most meaningful result for most people. And as you can see, the SSD cache performs extremely well, giving a huge performance boost over a standard mechanical HDD.

Web Development

Combine images, video clips, and audio into a video using a video editing application, then encode the video to a web-ready format. Layout the graphics and create the icons for a website using an image editing application. Use batch processing to manipulate a set of photos for use in a web-based photo gallery. Assemble the graphics, gallery, and video into a functional website using a web development application, fixing links and moving documents as needed. Preview the pages in multiple web browsers.

Programs Used:

  • Adobe Photoshop CS5 Extended
  • Adobe Premiere Pro CS5
  • Adobe Dreamweaver CS5
  • Microsoft Internet Explorer 8
  • Mozilla Firefox 3.6.8

SSD Cache Performance in Web Development

Likewise, the web development suite benefits from both a pure SSD and SSD cache dramatically.

Data/Financial Analysis

Generate sales forecasts by region and currency based on historical data, and produce summary graphs and pivot tables using a spreadsheet application.

Program Used:

  • Microsoft Excel 2010

SSD Cache Performance in data analysis - Excel

Loading spreadsheets in Excel is much faster with an SSD, and an SSD cache is just as good in this test.

System Management

Install and then upgrade an application using a complete application installer and patch installers. Perform a (simulated) full system backup using encryption, then after making changes to the initial backup dataset, perform two encrypted incremental backups. Restore both backups. Create an encrypted archive of various sensitive files for transfer across unsecured communications, and another unencrypted archive of various files. Decompress the initial backup and two incremental backups. Decompress the encrypted
and unencrypted archive files.

Programs Used:

  • Mozilla Firefox (multiple versions)
  • WinZip Pro 14.5
  • WinZip Command Line 3.2

SSD cache performance in system management - Winzip

This test includes a lot of file reading and writing with encryption and compression. Once again, the SSD cache performs just as good as a standalone SSD.

Once again I’ll remind you that this is an overall system performance test, so the fact that scores are so dramatically improved by simply installing a $100 drive and using it as a cache is pretty impressive, and actually just about tells us all we need to know.

Before we move onto any conclusions though, let’s take a look at gaming performance:

Gaming Performance

To see how an SSD cache can effect gaming performance, we’ll load up a few games and measure level load times. Tests were run three times (to allow the data to be cached), with a reboot between each run (otherwise RAM comes into play).

SSD cache performance - Batman Arkham City

SSD cache performance in Portal 2

SSD cache performance in Skyrim

Once a game is cached, the level loads just as it would off a dedicated SSD. If you are wondering how long it takes or how many loads it takes for a game to get cached, the answer, in my experience, is once. You might have to put up with a 15-20 second level load if you haven’t played the game for a while, but once you do, the data gets cached, and it begins running off the SSD again. All this is done without any interference from the user.

Conclusions

My motivation for writing this article stemmed from complaints from friends and readers who didn’t want to make the leap to an SSD due to the cost of drives that have sufficient capacity to run all their programs from. For some people, moving files back and forth from a small SSD isn’t too much of a hassle, but many find it to be a waste of time. And when you have to run most programs from a mechanical drive, what’s the point of even having an SSD?

After looking at our test results, I think it’s pretty clear that if you only want to spend around $50-100 on an SSD, caching is the way to go. In my experience, commonly used programs and data gets send to the SSD efficiently (and it’s even better if you are installing onto a cached drive rather than adding a cache later).

Alternatively, you could buy a 50 or 64GB drive and use that as a cache. This won’t be as fast as a 128GB with 50% over-provisioning, but it is easily the best $50 you’ll ever spend on your PC. In fact I would say that if you have an Intel board that supports Smart Response, there is no reason not to use it at this point. Get yourself an SSD – anything from a 32GB to a 128GB, and make use of caching today. You will never want to go back to a mechanical drive.

If you are already using a small SSD as your main drive, and still running programs off a mechanical drive, it is still worthwhile to get a second SSD and use that to cache the mechanical drive. I think we’re at the point now where small SSDs are cheap enough that everyone should have an SSD cache.

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