The Downside: Consistency

Initially it's very easy to get excited about Intel's SRT. If you only run a handful of applications, you'll likely get performance similar to that of a standalone SSD without all of the cost and size limitations. Unfortunately, at least when paired with Intel's SSD 311, it doesn't take much to kick some of that data out of the cache.

To put eviction to the test, I ran through three games—Portal 2, Starcraft 2 and World of Warcraft—then I installed the entire Adobe CS5.5 Master Collection, ran five of its applications and tried running Starcraft 2 again. All of Starcraft 2's data had been evicted from the SSD cache resulting in HDD-like performance:

Starcraft 2 Level Loading—Seagate Barracuda 3TB (Maximize Cache)
  Load Time Load Time After App Install/Launch
Game Launch 9.7 seconds 17.4 seconds
Level Load 15.0 seconds 23.3 seconds

I thought that may have been a bit excessive so I tried another test. This time I used the machine a bit more, browsed the web, did some file copies and scanned for viruses but I didn't install any new applications. Instead I launched five Adobe applications and then ran through all of our game loading tests. The result was a mixed bag with some games clearly being evicted from the cache and others not being touched at all:

Game Load Comparison
Intel SSD 311 20GB Cache Portal 2 (Game Launch) Portal 2 (Level Load) Starcraft 2 (Game Launch) Starcraft 2 (Level Load) World of Warcraft (Game Launch) World of Warcraft (Level Load)
Load Time 9.9 seconds 15.1 seconds 9.7 seconds 15.0 seconds 4.5 seconds 5.8 seconds
Load Time After Use 12.1 seconds 15.1 seconds 10.1 seconds 15.3 seconds 3.6 seconds 14.0 seconds

Even boot time was affected. For the most part performance didn't fall back down to HDD levels, but it wasn't as snappy as before when I was only running games.

Boot Time—Seagate Barracuda 3TB (Maximize Cache)
  Time
Boot Time 32.6 seconds
Boot Time After Use 37.3 seconds
Boot Time Without Cache 55.5 seconds

Although Intel felt that 20GB was the ideal size to balance price/performance and while SRT is supposed to filter out some IO operations from being cached, it's clear that if you frequently use ~10 applications that you will evict useful data from your cache on a 20GB SSD 311. For lighter usage models with only a few frequently used applications, a 20GB cache should be just fine.

There's also the bigger problem of the initial run of anything taking a long time since the data isn't cached. The best way to illustrate this is a quick comparison of how long it takes to install Adobe's CS5.5 Master Collection:

Install Adobe CS5.5 Master Collection
  Time
Seagate Barracuda 3TB (No cache) 13.3 minutes
Seagate Barracuda 3TB (Maximize Cache) 13.3 minutes
OCZ Vertex 3 240GB (6Gbps) 5.5 minutes

A pure SSD setup is going to give you predictable performance across the board regardless of what you do, whereas Intel's SRT is more useful in improving performance in more limited, repetitive usage models. Admittedly most users probably fall into the latter category.

In my use I've only noticed two reliability issues with Intel's SRT. The first issue was with an early BIOS/driver combination where I rebooted my system (SSD cache was set to maximized) and my bootloader had disappeared. The other issue was a corrupt portion of my Portal 2 install, which only appeared after I disabled by SSD cache. I haven't been able to replicate either issue and I can't say for sure that they are even caused by SRT, but I felt compelled to report them nevertheless. As with any new technology, I'd approach SRT with caution—and lots of backups.

 

Application & Game Launch Performance: Virtually Indistinguishable from an SSD AnandTech Storage Bench 2011 - Heavy Workload
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  • KayDat - Wednesday, May 11, 2011 - link

    I know this bears zero relevance to Z68...but that CGI girl that Lucid used in their software is downright creepy. Reply
  • SquattingDog - Wednesday, May 11, 2011 - link

    I tend to agree - maybe if she had some hair it would help...lol Reply
  • RamarC - Wednesday, May 11, 2011 - link

    Seems that it would be better to designate a partition to be cached and other partitions uncached. With only a 20GB cache SSD, ripping from BD to .MP4 could easily cause cache evictions.

    And, will this work with a mixed Rapid Storage array? I typically run hard drives in pairs, and mirror (raid 1) the first 120GB and stripe the remaining so I've got a fault-protected 120GB boot device and a 1700GB speedster. In this case, I'd only want the boot device cached.
    Reply
  • ganeshts - Wednesday, May 11, 2011 - link

    This looks like a valid concern. For HTPCs, there is usually a data partition separate from the boot / program files partition. Usage of the SSD cache for the data partition makes no sense at all. Reply
  • velis - Wednesday, May 11, 2011 - link

    I agree with validity of this proposal, but must also comment on (non)sensicality of caching the data partition:
    I for one was disappointed when I read that multi-MB writes are not (write) cached. This is the only thing that keeps my RAID-5 storage slow. And a nice 32GB cache would be just the perfect thing for me. That's the largest I ever write to it in a single chunk.
    So instead of 100MB/s speeds I'm still stuck with 40 down to 20MB/s - as my raid provides.

    Still - this is not the issue at all. I have no idea why manufacturers always think they know it all. Instead of just providing a nice settings screen where one could set preferences they just hard-code them...
    Reply
  • fb - Wednesday, May 11, 2011 - link

    SRT is going to be brilliant for Steam installs, as you're restricted to keeping all your Steam apps on one drive. Wish I had a Z68. =) Reply
  • LittleMic - Wednesday, May 11, 2011 - link

    Actually, you can use a unix trick known as symbolic link to move the installed game elsewhere.

    On WindowsXP, you can use Junction,
    On Windows Vista and 7, the tool mklink is provided with the OS.
    Reply
  • jonup - Wednesday, May 11, 2011 - link

    Can you elaborate on this or provide some links?
    Thanks in advance!
    Reply
  • LittleMic - Wednesday, May 11, 2011 - link

    Consider c:\program files\steam\...\mygame that is taking a lot of place.

    You can move the directory to d:\mygame for instance then you can use the command

    vista/7 (you need to be administrator to be able to do so)
    mklink /d c:\program files\steam\...\mygame d:\mygame

    xp (administrator rights required too)
    junction c:\program files\steam\...\mygame d:\mygame

    to create the link.

    The trick is that steam will still find its data in c:\program files\steam\...\mygame but they will be physically located on d:\mygame.

    Junction can be found here :
    http://technet.microsoft.com/fr-fr/sysinternals/bb...
    Reply
  • LittleMic - Wednesday, May 11, 2011 - link

    Update : see arthur449 suggestion.
    Steam mover is doing this exact operation with a nice GUI.
    Reply

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