hard drive - Making SSD & HDD work together like a hybrid

  • Paul Johnson

    I have a 90GB SSD but 90GB soon gets filled up. My users folder alone is 26GB. To get round this I use Symlinks (read the How-To Geek article for more).

    Is there any way to make a separate SSD and HDD work like a hybrid so that frequently accessed files are moved to the SSD automatically? This would be a nice addition to Windows 8 but I'm not holding out my hopes.

    I guess ReadyBoost is a bit like this but its more designed for USB sticks I think. I did try installing Windows 7 with the SSD as a readyboost but didn't really notice any much improvement over just using the HDD.

  • Answers
  • Mark Booth

    Given that hybrid hard drives like the Momentus® XT never really took off (there is only one manufacturer, so tier 1 OEMs will not use them, plus current drives and only cached reads anyway), it looks like there are limited options for SSD hard drive caching, an add in SATA card or a software solution.

    More recent drives like the Seagate 3rd generation solid state hybrid drive (SSHD) look more promising, but there are trade-offs. They can allegedly cache some writes, but at the moment they still have very little flash (8GB MLC, with a small portion of the NAND set aside for use in SLC mode, similar to SanDisk’s nCache) and they are only 5400rpm drives.

    Unfortunately, none of the current options can make normal hard drives perform like SSD's. At best you get performance somewhere between SSD & HD and at worst you get performance which is even lower than the HD on it's own.

    On the plus side, if you are upgrading an old SSD then using that old SSD to cache your large storage drive could be an excellent option. SSD caching seems to benefit much less from newer, faster SSDs so you get most of the caching benefit from older, relatively slow SSDs.

    Add-in SATA cards

    One option is an add-in SATA card which can provide this functionality. I believe there are enterprise level solutions for this, but as they are well out of my price range I haven't researched them. The HighPoint RocketHybrid 1220 is much more affordable though, and there is a nice article about this on Tom's Hardware Guide.

    My experience with the Add-in SATA card option.

    Having seen the Add-in SATA card option in action, I have to say that I'm not impressed with the Marvell 88SE9130 based card that I bought. HyperDuo was incredibly unreliable, the software kept crashing and the performance was rarely higher than the underlying hard drive on its own, even after hours of optimisation.

    Even using the card as a 6Gbps SATA III port resulted in worse performance with an Adata S511 than just using the on-board 3Gbps SATA II ports.

    Intel Smart Response Technology (may require a motherboard upgrade)

    Another option is to upgrade to a motherboard with an Intel Z68 chipset, or newer chipset that supports Intel Smart Response Technology. Again, THG has a nice article providing an overview of what we can expect of the SSD caching capabilities of this chipset.

    My experience with the Intel SRT option.

    After having had the opportunity to play with a Z68 based motherboard, I was even less impressed with Intel Smart Response Technology than I was with HyperDuo!

    At the time Smart Response Technology could only cache a Windows boot drive, so you couldn't have an SSD Boot drive and then use SRT to cache another drive in your system. You had to install Windows on the hard drive, install drivers, then the Intel® Rapid Storage Technology (RST) software and then add the SSD. At this point, if you were lucky then you would be able to see a new "Accelerate" tab on the RST application and if not then you may have to start the whole process from scratch to try and get it to work.

    Apparently (thanks Nicholas) more recent versions of RST are substantially better. I haven't tried this yet, but apparently you can now cache a non boot hard drive as long as you start with a completely blank SSD (no partitions). You are still limited to 60GB of cache, but once the drive is set up as a cache, the remainder of the drive can be configured as a normal partition. Sadly you are still limited to caching a single drive or raid array.

    Alternative software caching options

    The last option is a non-Intel software caching solution, like Dataplex, which is bundled with the OCZ Synapse SSD. Unfortunately, this solution (like Intels SRT) currently only supports caching a single boot drive, so the only benefit is that it doesn't require a Z68 motherboard.

    Unfortunately, I have yet to see a review from a site whose methodology I trust, so I can't tell how this option compares with SRT or the add-in card option.

    Final option: Don't bother, just manage your storage manually

    Fire and forget solutions are all well and good, but sometimes it's just easier to manage these things yourself. Use your SSD and hard drive as separate drives, put stuff that you don't need fast access to on the HD and stuff that do on your SSD. Move thisgs between than as and when you need to.

    Tools like NTFS symbolic links, SSD Boost Manager and Folder2Junction could all help. See my answer to Trying to make SSD boot drive with Windows 7 and old drive is not accessible for more details.

  • Mr Alpha

    There are a few options:

    1. Intel's newest chipstes, the Z68, have a technology called Smart Response Technology which does exactly that. It uses an SSD as a cache for frequently read files, and for small writes. This only workd on the Z68, though.
    2. DiskKeeper is making a piece of software called Express Cache which does essentially the same thing as the Intel solution. It is only available for OEMs, though, so you would have to get it with a machine.
    3. Several RAID card manufacturers have launched or announced products which allow you to use an SSD as a cache for an RAID array.

  • Related Question

    performance - Do SSD hybrid drives perform better than HDD + ReadyBoost flash?
  • Chris W. Rea

    Seagate has released a product called the Momentus XT Solid State Hybrid Drive. This looks exactly like what Windows ReadyBoost attempts to do with software at the OS level: Pairing the benefits of a large hard drive together with the performance of solid-state flash memory.

    Does the Momentus XT out-perform a similar ad-hoc pairing of a decent hard drive with similar flash memory storage under Windows ReadyBoost?

    Other than the obvious "a hardware implementation ought to be faster than a software implementation", why would ReadyBoost not be able to perform as well as such a hybrid device?

  • Related Answers
  • Jeff Atwood

    One major difference is that ReadyBoost is limited to USB 2.0 bandwidth (unless your computer has the ultra-rare and extremely bleeding edge USB 3.0), whereas the hard drive is on the much, much faster SATA interface.

    Thus, putting fast flash memory on SATA alone is enough of a win to say definitively that it will be faster.

    ReadyBoost is also designed around relatively slow I/O constraints, which limits the scope of what it can do, too.

    The one review I found was quite positive. It does seem like, with the right algorithms, you could have the best of both worlds here -- the speed of a SSD (mostly) and the capacity and low price-per megabyte of a traditional HDD.

  • Andy

    I reckon it will not be the technology that's a winner here, it will be the algorithm used to decide what to store where. Seeing as we don't know the algo for Vista, Win7, or the hybrid, I guess it will take empirical evidence to get a reasonable answer. Having said that, the OS can run more complicated algorithms, look at usage patterns over longer periods, and understand the filesystem itself better, so perhaps there's more potential there. One possible slowdown to ReadyBoost is that it has to encrypt everything because it's assuming removable media, whereas the hybrid solution has no such constraint.

    "a hardware implementation ought to be faster than a software implementation"

    I'm not sure that has to be true, but you get the advantage of knowing that if your computer's under a heavy workload, the hard drive will still operate at optimal speed. Edit: also it keeps your data buses emptier.

    An advantage I see to ReadyBoost is that you've separated the two storage technologies, so you can update them independently as prices decrease or technology improves.

  • user626528

    You are wrong with this assumption; ReadyBoost and hybrid drives are completely different. ReadyBoost was designed to "extend RAM" to help low-level machines, while hybrid drives are designed to improve disk performance for top level machines. The way how ReadyBoost works is: read data from HDD into RAM first, and if you out of RAM push data from RAM to flash drive. ReadyBoost can't improve performance if you have plenty of RAM (actually, it will rather slow your system down).