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Samsung 850 EVO and TRIM?

Dear friends,


Yesterday I installed a brand new SAMSUNG 850 EVO SSD (120 gb) on my MacBook Pro (mid 2012) and I want to know now should I enable TRIM and is it safe under the OS X EL CAPITAN!?


Again its SAMSUNG 850 EVO (120 gb, basic version not pro), MacBook Pro (mid 2012) and OS X EL CAPITAN!!!


Thank you for answer.

MacBook Pro (13-inch Mid 2012), OS X El Capitan (10.11.3), null

Posted on Jan 24, 2016 2:19 AM

Reply
26 replies

Sep 26, 2016 2:40 AM in response to MediaMind

I had previously googled extensively regarding TRIM on Samsung SSDs.


I installed my Samsung 850 EVO 250GB SSD on my Macbook Pro 13" mid 2010 and decided not to enable TRIM.


fast forward 9 months later, i feel my applications might be slightly slowered and my application "clean my Mac 3" tells me that i need to repair my startup disk.


today, i repaired it and enable TRIM, hopefully this works for me as well as for people who has the same questions.


I believe it will be faster and so far my laptop feels great, if not greater and ever so slightly faster.

Sep 26, 2016 10:28 AM in response to Wantonman

When you delete a file from a HD, the space it occupied can be written to immediately. When you delete a file from an SSD, the space needs to be erased first by the SSD controller.


Two gotchas. First, the minimum contiguous space that can be erased is often larger than what the file occupied so before erasure, all the still good stuff in that space has to be moved somewhere else first. Second, the HD and the OS both know about file deletion making the space free, but the SSD controller doesn’t, so when the good stuff is moved prior to erasure, the deleted stuff goes too.


TRIM is the function built into the OS that tells the SSD the deleted file’s space is erasable but it’s only on by default with Apple SSDs. That’s what enabling TRIM is for with non-Apple SSDs.


A key idea is that the space is flagged as available when the deletion takes place which means TRIM must be running continuously to get full benefit and any such benefit is lost for deletions prior to TRIM being enabled. So there will be no sudden magical fix for a drive slowing down because the SSD controller’s Garbage Collection has previously had to deal with “secretly” deleted files which are still taking up space.

Sep 26, 2016 8:34 PM in response to Wantonman

Considering that your SSD has been in use for quite a while and the contents would need to be reconstructed from scratch (unless you have a clone you could restore from), I don't think you'd need to go that far.


While TRIM is a definite aid to the Garbage Collection routines which SSD controllers use, they can, over time get by without it. I'm a Crucial SSD fan and one of their suggestions is to allow some powered up quiet time for GC. With a Mac, a way to get that is to boot with the Option key down. This invokes the Startup Manager and while the connected bootable devices appear in a row, they aren't actually in use. I don't prefer that method only because things tend to get warm inside and I can't use smcFanControl to keep things cool.


BTW, another thing to consider is that the relocation of valid data before erasure has to go somewhere. SSD manufacturers provide "overprovisioning," often 7% of the available space, that's unavailable to the user but available to the SSD controller. If your drive is big enough and you don't need all of it's capacity, when you create the partition, you can leave some space free, and, again, while it's not available to you, it gets included in the overprovisioning space for use by the controller. For example, check out this review of the Samsung 840 EVO. You can compare the performance with the default overprovisioning and 25% OP.

Samsung 850 EVO and TRIM?

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