Impact of Idle Garbage Collection

The other option that Indilinx provides its users to improve used performance is something called idle or background garbage collection. The idea is that without any effort on your or the OS’ part your drive, while idle, will defragment itself.

The feature was actually first introduced by Samsung for its RBB based drives, but I’ll get to the issues with Samsung’s drives momentarily.

It either works by looking at the data on the drive and organizing it into a less fragmented state, or by looking at the file system on the drive and attempting to TRIM based on what it finds. Both Indilinx and Samsung have attempted to implement this sort of idle garbage collection and it appears they do it in different ways. While the end result is the same, how they get there determines the usefulness of this feature.

In the first scenario, this is not simply TRIMing the contents of the drive, the drive doesn’t know what to TRIM; it must still keep track of all data. Instead, the drive is re-organizing its data to maximize performance.

The second scenario requires a compatible file system (allegedly NTFS for the Samsung drives) and then the data is actually TRIMed as it would be with the TRIM instruction.

Details are slim, but the idle garbage collection does work in improving performance:

PCMark Vantage HDD Score New "Used" After TRIM/Idle GC % of New Perf
Corsair P256 (Samsung MLC) 26607 18786 24317 91%

 

Presumably this isn’t without some impact to battery life in a notebook. Furthermore, it’s impossible to tell what impact this has on the lifespan of the drive. If a drive is simply reorganizing data on the fly into a better (higher performing) state, that’s a lot of reads and writes when you’re doing nothing at all. And unfortunately, there’s no way to switch it off.

While Indilinx is following in Samsung's footsteps with enabling idle garbage collection, I believe it's a mistake. Personally, real TRIM support (or at least the wiper tool) is the way to go and it sounds like we’ll be getting it for most if not all of these SSDs in the next couple of months. Idle garbage collection worries me.

The Wiper Tool Early TRIM Support on Indilinx Drives
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  • valnar - Wednesday, September 2, 2009 - link

    Anyone?
  • antinah - Tuesday, September 1, 2009 - link

    For another great article on the SSD technology.

    I'm considering an Intel G2 for my brand new macbook pro, and if I understand what I've read correctly, performance should not degrade too much although OSX doesn't support trim yet.

    I also doubt Apple will wait too long before they release an update with trim support for osx.

    I just recently switched to mac after a lifetime with pc/windows. Anything i shoud be aware of when I install the SSD in a mac compared to pc running windows? (other than voiding the warranty and such). I'm thinking precations regarding swap usage or such.

    Best regards from norway
    Stein
  • medi01 - Tuesday, September 1, 2009 - link

    So I absolutelly need to pay 15 times as much per gigabyte as normal HDDs, so that when I start Photoshop, Firefox and WoW, straight after windows boots, it loads whopping 24 seconds faster?

    That's what one calls "absolutelly need" indeed and you also chose amazingly common combination of apps.
  • Anand Lal Shimpi - Tuesday, September 1, 2009 - link

    You can look back at the other two major SSD pieces (X25-M Review and The SSD Anthology) for other examples of application launch performance improvements. The point is that all applications launch as fast as possible, regardless of the state of your machine. Whether you're just firing it up from start (which is a valid use scenario as many users do shut off their PCs entirely) or launching an application after your PC has been on for a while, the apps take the same amount of time to start. The same can't be said for a conventional hard drive.

    Take care,
    Anand
  • Seramics - Tuesday, September 1, 2009 - link

    its not abt the 24seconds but rather the wholly different experience of near instantaneous u get wit ssd tht cannot be replicated by hdds
  • medi01 - Tuesday, September 1, 2009 - link

    Nobody starts mentioned apps together directly after boot.

    I've played WoW for a couple of years, and never had to wait dozen of seconds for it to start.

    Most well written applications start almost instantly.

    And the whole "after fresh boot" is not quite a valid option neither, I don't recall when I last switched off my pc, "hibernate" works just fine.

    The "you get completely different experience" MIGHT be a valid point, but it was destroyed by ridiculous choice of apps to start. And I suspect that it is because NOT starting stuff all together and right after boot, didn't show gap as big.
  • kunedog - Tuesday, September 1, 2009 - link

    Anand, I think your article titled "Intel Forces OCZ's Hand: Indilinx Drives To Drop in Price" (http://www.anandtech.com/storage/showdoc.aspx?i=36...">http://www.anandtech.com/storage/showdoc.aspx?i=36... could also use a follow-up, primarily to explain why the opposite has happened (especially with the Intel drives). Is this *all* attributable to Intel's disaster of a product launch? Maybe not, but in any case it deserves more attention than a brief mention at the end of this article.
  • zero2espect - Tuesday, September 1, 2009 - link

    great work again. it's for this reason that i've been coming here for ages. great analysis, great writing and an understanding about what we're all looking for.

    one thing that you may have overlooked is the difference in user experience due to the lack of hdd "buzz". fortunate enough to find myself in posession of a couple of g2160gb jobbies, one is in my gaming rig and the other in the work notebook. using the notebook the single biggest difference is speed (it makes a 18mo old notebook seems like it performs as fast as a current generation desktop) but the next biggest and very noticible difference is the lack of "hum", "buz", "thrash" and "vibrate" as the drive goes about it's business.

    thanks anadtech and thanks intel ;-P
  • Mr Perfect - Tuesday, September 1, 2009 - link

    Anand,

    Would you happen to know if there are different revisions of the G2 drives out? Newegg is listing a 80GB Intel drive with model #SSDSA2MH080G2C1 for $499, and another 80GB Intel with model #SSDSA2MH080G2R5 for $599. They are both marked as 2.5" MLC Retail drives, and as far as I can tell they're both G2. What has a R5 got that a C1 doesn't? The updated firmware maybe?

    Thanks!

    PS, dear Newegg, WTF? 100% plus price premiums? I'm thinking I'll just wait until stock returns and buy from another site just to spite you now....
  • gfody - Tuesday, September 1, 2009 - link

    It looks like the R5 is just a different retail package - shiny box, nuts and a bracket instead of just the brown box.
    Why Newegg is charging an extra $100 for it.. just look at what they're doing with the other prices. I am losing so much respect for Newegg right now. disgusting!

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