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As of Yosemite, DIY, or non-Apple installed SSDs have Trim support challenges using applications such as Trim Enabler. Assuming one keeps their TRIM supported SSD in Yosemite,

  1. what is a good strategy for using Trim Enabler periodically so there are no issues with kext-signing and potential OS update conflicts while Trim Enabler is disabled?
  2. Can this be worked around by periodically using Trim Enabler?
  3. How long should Trim Enabler be run?
  4. How often?
  5. If SSD usage, e.g. amount of read/written data is relevant to how long/often Trim Enabler should be run, is there a way to evaluate guidelines on light, moderate, heavy use.

An excellent feature for TE would be a scheduler to run based on need, then toggle TE off and turn kext-signing back on after a scheduled maintenance run. At least until/if Apple ever reopens kext-signing to software and hardware devs. Cheers -

thepen
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1 Answers1

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What I used to do was enable TRIM, reboot, create and delete an encrypted disk image that almost filled the free space, leave my MBP idling overnight, disable TRIM, and reboot. That restored performance.

I'm not sure r/w volumes will tell you anything useful. The OS reuses erased blocks and the current controllers garbage collection is supposed to make TRIM largely irrelevant (or at least that's what I read).

I don't have that machine anymore and it seems like a lot riskier process under 10.10 so I'm not doing anything with TRIM on my Mac Mini w/ a Samsung 840 EVO.

thepen
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Bill Tanner
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  • Interesting strategy. Sorry, to clarify, what is "APand reboot"? I was reading up on TRIM and garbage collection earlier, here's what I learned so far: Trim may be an aid to garbage collection to reduce writes, improving longevity. Sorry to hear you're not using your comp because of this. I'm in limbo on putting a Samsung SSD into my Mac Mini until this gets sorted. – thepen Dec 22 '14 at 03:29
  • That was just a typo (fixed). TRIM/SSD had nothing to do with why I got rid of my MBP. Don't let worrying about this issue keep you from upgrading. The safest option is to get a drive from OWC because they are intended for use under OSX. I put an OWC SSD in my wife's mid-2009 MBP and never saw a performance drop even though she ran it 95% full. Only you can say if it's worth the premium. – Bill Tanner Dec 23 '14 at 05:17
  • When you said "I'm not doing anything with my Mac Mini w/ a Samsung 840 EVO," does that mean you're not using it because of the TRIM issue or something else? – thepen Dec 24 '14 at 21:10
  • I'm not doing anything with TRIM on it. The Mac Mini w/ SSD is heavily used every day. At this point, I'm just hoping that plenty of free space and the controller's garbage collection is sufficient to maintain performance – Bill Tanner Dec 25 '14 at 22:12
  • Assuming you're using Yosemite in your Mini and wife's machine, otherwise Trim Enabler remains viable with kext signing intact. Apparently TRIM prevents write amplification even in Sandforce (OWC) SSDs. Cinder.org has something on this here. – thepen Jan 02 '15 at 00:59
  • Samsung highly recommends TRIM under OS X, but that requires alteration of a kernel extension (kext). In 10.10, Apple includes a system check again all kexts and fails to load if one is found altered. But it's more of an initial security step and exploiting kexts isn't a huge security concern (seeing as it can be done in 10.9 and lower versions of OS X. You shouldn't feel wary about disabling OS X kext sanitation, especially since Samsung apparently admits their drivers perform a hell of a lot better with TRIM running. If I still ran my Samsungs, I would too under 10.10, all things considered. –  Jan 02 '15 at 02:05
  • Data on the 840 EVO and TRIM: http://www.anandtech.com/show/7173/samsung-ssd-840-evo-review-120gb-250gb-500gb-750gb-1tb-models-tested/6 –  Jan 02 '15 at 02:09
  • @cksum Thanks for the link! I think you mean you'd run TRIM on your Samsungs if you still ran them? Interesting you think kext signing isn't a security issue when apple implemented it, presumably to ameliorate a security risk? Some say apple is just preventing 3rd party SSD to promote obsolescence. Thoughts? I'm currently running 2 Samsungs in raid0 with plants of free space with no performance loss after 4 months. Still concerned about accelerated failure from write amplification sans TRIM. Hoping the 850 EVO nand is robust enough to handle. – thepen Mar 26 '15 at 03:45