SSD - A question of Garbage Collection

Discussion in 'MacBook Pro' started by DimensionDude, May 21, 2012.

  1. DimensionDude macrumors newbie

    Joined:
    May 18, 2012
    #1
    Hi all,

    Installed a Samsung 830 (256GB) in my 2010 MacBook Pro 15" just last week.

    I'm still running Snow Leopard and did not enable Trim.

    It runs great, very snappy performance so no complaints there.

    However, various posts I've read indicate that the computer should be left idle for a couple of hours to allow the SSD controller to perform its garbage collection routine.

    Should I increase the idle period before sleep when running on AC power? If the hard drive is sleeping will the controller not be able to perform the routines or will the drive be awakened?
     
  2. SDAVE macrumors 68040

    SDAVE

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    #2
    Don't enable Trim. The Samsung's are good drives and considered top tier.

    During sleep, the SSD doesn't work.

    Just use it as you would and it will be fine.
     
  3. DimensionDude thread starter macrumors newbie

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    May 18, 2012
    #3
    Hi SDAVE, thanks for the reply.

    I'd gathered from extensive reading that the Samsung was the way to go.

    Currently, my MBP is set for a 15 minute idle before sleep when running on AC power (the default I assume, since I haven't changed it). I'm wondering if that's enough time for the controller to do its thing when necessary. Perhaps even more extensive reading will be needed but it's a bit easier if someone can just tell me the answer. :D
     
  4. SDAVE macrumors 68040

    SDAVE

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    #4
    Just set it and forget it :)

    I'm sure during use you're not writing/reading an insane amount of data, so the drive does stuff on it's own.

    I've had no issues whoatsoever, it's been 2 months with a Samsung 830. Love it. Speed is still fast as I bought it. Drive is almost full.
     
  5. Donka macrumors 68020

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    Location:
    Scotland
    #5
    Don't confuse time before sleep with drive idling.
    If you are using your Mac but the drive is not doing anything then that is considered idle time for the drive and GC will kick in then.
    If you are busy reading and writing lots of files then the drive will not have any idle time but for the average consumer this is actually quite rare. As others have said, just use it as normal and don't feel the need to extend the time before sleep setting.
    If you are always doing intensive tasks such video conversions or the like then you may have a need to set aside some quiet time for your Mac but otherwise you are most likely fine.
     
  6. DimensionDude thread starter macrumors newbie

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    May 18, 2012
    #6

    Sounds good to me. I ran Blackmagic Disk Speed Test directly after installation and saved a screenshot. I'll do a comparison in a couple of months.
     

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  7. dusk007 macrumors 68040

    dusk007

    Joined:
    Dec 5, 2009
    #7
    You bought an expensive Samsung 830 to run on SATA 2?
    That is nuts.

    You won't need a whole lot of GC on a big enough drive. BTW Trim doesn't work without GC, GC is never as effective without Trim.
    Eventually when you have written enough Data to your drive it will behave like a full drive. Because without Trim you cannot ever delete anything, you can only write over old data. GC just combines Data if there are lots of random writes to different locations.
    Most consumers often write movie files, images like dmg and such stuff onto the drive. A write with such big sequential files works just like GC just, faster and with better results. Therefore most consumers that use the SSD also a little for data and not only the pure OS are in the green.

    Trim helps to not get the slower speed of an always full drive, most of these new drives do work quite well when filled up though. I don't know about Lion in SL my own tests showed that Trim does help and should be used. I didn't notice any significant problems but it does keep performance up top.

    Additionally one can enable Trim temporarily and do an Earse Free Space with Diskutility. That pretty much does what Trim is doing all the time in one swoop. Afterwards you can disable Trim again.
     
  8. bvanlieu macrumors member

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    Dec 28, 2008
    #8
    Um...no its not. Just because the laptop is not SATA III doesn't mean its a bad idea. You get a drive from a *very* reliable manufacturer that is not much more then others drives.

    The Samsung 470 is not necessarily less expensive (wasn't when I bough my 830), and the 830 gives you an upgrade path as well. Get a new lappy? You are all set to move the SSD over for SATA III.

    As for TRIM, depends on your use. I have run the 830 for 6 months now and never enabled it. My AJ speed tests show the same R/W performance within standard deviation of the day I put it in.

    If that was to drop I have no issues enabling TRIM then disabling it but the sky is not falling with no TRIM in my environment :)

    - b
     
  9. dusk007 macrumors 68040

    dusk007

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    Dec 5, 2009
    #9
    Last time I checked it was 25% more per GB than a m4 also rather reliable and gets you the same performance.
    I wouldn't put to much in the carry along bucket, unless an upgrade is intended rather soon. Otherwise before one upgrades the small 1" mSATA SSDs will be standard in any new Notebook one buys. That would be something to invest in.

    If there is enough sequential data writes those generic controllers like the Samsung, Mircon .. do pretty good with out Trim.
    I meant to explain that GC is not a true substitute to Trim. Some people seem to think that it is two different approaches to a problem. Trim alone without any GC wouldn't really do all such a great job and GC without Trim can only do so much.
     
  10. DimensionDude thread starter macrumors newbie

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    May 18, 2012
    #10
    Yup, I bought an expensive Samsung 830 to put into an expensive Apple notebook. ;)

    Thanks to all for the helpful info. Looks like the thing to do is run as-is for a few months to see what happens. If it becomes necessary, I will enable Trim, perform a "clean up," and then disable Trim. :)

    ----------


    Excellent! :D

    This clears things up considerably and make a lot of sense. :)
     
  11. jamin00 macrumors 6502

    jamin00

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    #11
    Would this sort of thing apply to all SSD's or just Samsung's?
     
  12. Donka macrumors 68020

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    #12
    I believe all SSD drives have some form of garbage collection however they are all different in how they are implemented. Probably best to read reviews on any drives of interest to see how such functionality is rated.
     
  13. Basic75 macrumors regular

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    May 17, 2011
    #13
    Most modern SSDs with trim, it's how I handle my Intel 320 Series (usually run with TRIM enabled, don't care when a software update disables it but eventually enable it and force a TRIM via fsck).
     
  14. CosmoPilot macrumors 65816

    CosmoPilot

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    South Carolina
    #14
    Wirelessly posted

    Does the Crucial M4 have ant type of GC, or do you have to enable TRIM from time to time?

    How long between if SSD writes are light?
     
  15. Weaselboy Moderator

    Weaselboy

    Staff Member

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    Location:
    California
    #15
    Yes the M4 does have garbage collection built in firmware and should work just fine on its own without enabling TRIM.

    Read this well researched review of another drive with the Marvell controller used in the M4. Focus on the TRIM testing toward the end of the article. This is the best review I have seen discussing garbage collection on OS X.

    The author is a mod here in the forums named Hellhammer.

    For others in the thread, if you do want to TRIM your drive, just enable the TRIM hack then reboot in single user mode and type in the command "fsck -fy" without the quotes. This will TRIM all unused blocks on the SSD.
     
  16. jamin00 macrumors 6502

    jamin00

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    #16
    Thanks, this was the answer to my next question as well :)
     
  17. CosmoPilot macrumors 65816

    CosmoPilot

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    #17
    So for the M4, I should be able to install it and not worry about any maintenance? It will have very light useage (writes) after its configured with the OS.

    What about OSX updates, do these effect SSDs? If so, how do you determine to update the OS or not without causing SSD problems?

    Thanks again, everyone has been a huge help as I venture into SSD land.
     
  18. IngerMan macrumors 6502a

    IngerMan

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    Feb 21, 2011
    Location:
    Michigan
    #18
    I Have had the M4 and a few Lion OS updates. No problems so far on Lion. I might wait a few weeks for 10.8 ML to hear that every thing is fine and read the Crucial site for any updates. Running 000f and No Trim. I had Trim installed in the beginning but decided to give it a go with out it.
     
  19. CosmoPilot macrumors 65816

    CosmoPilot

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    South Carolina
    #19
    This is awesome news as UPS has an M4 with my name on it!

    Thanks again.
     
  20. omr macrumors member

    omr

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    #20

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