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Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Macintosh software/hardware discussion and troubleshooting

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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Sat May 07, 2016 10:55 am

mikehalloran wrote:Samsung SSD 850 EVO 2TB


Mike, this SSD is among the ones that are blacklisted for use of TRIM.
The issues are not immediately obvious, when you delete data, sometimes the wrong data get deleted.


Hope this has not happened to you, and that you have a full working backup, from before you enabled TRIM.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby bayswater » Sat May 07, 2016 1:26 pm

Can you post a link for the blacklist? All the references I've seen were specific to Linux.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Sat May 07, 2016 2:24 pm

bayswater wrote:Can you post a link for the blacklist? All the references I've seen were specific to Linux.



SSDs can be built into computers running Windows, OS X, Linux. That's only software that's installed on the SSD. It's my understanding that the issues affect all operating systems, because the firmware on the SSDs (which is completely independent of the OS) handles read/write operations incorrectly when TRIM commands are sent.


In the link to the arstechnica discussions I posted above, OS X users report the issue, another indication that the linked blacklist is not Linux exclusive, but applies to other OSs as well.


In the ars thread, users also explain that not everybody who has a 'blacklisted' SSD running with TRIM enabled is necessarily affected by the data loss bug. That being said, losing data, even over a period of time, may not lead to issues that are immediately obvious - e.g if parts of user files are corrupted that are not frequently used. In a case like that, the Time Machine back ups of these files would be broken as well, of course...

If you look at the screenshots in the Arstechnica article, you'll see that Apple specifically warns that there could be data loss when trimforce is executed and TRIM enabled:

Image
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby mikehalloran » Thu Jul 14, 2016 9:11 pm

stratology wrote:
mikehalloran wrote:Samsung SSD 850 EVO 2TB


Mike, this SSD is among the ones that are blacklisted for use of TRIM.
The issues are not immediately obvious, when you delete data, sometimes the wrong data get deleted.


Hope this has not happened to you, and that you have a full working backup, from before you enabled TRIM.
This has been thoroughly investigated and the general conclusion is that this is utter nonsense. Every Apple engineer I know recommends the Samsung 850 EVO and enabling TRIM.

I have had no problems in the year or so that has passed since I installed them in over 20 Macs including mine.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby HCMarkus » Thu Jul 14, 2016 10:46 pm

I think the problem is with Queued Trim in Linux. As Mike states, not an issue with OS X/macOS
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Fri Jul 15, 2016 6:31 am

mikehalloran wrote:This has been thoroughly investigated and the general conclusion is that this is utter nonsense.


Link please?


If it's utter nonsense, it would mean that Apple engineers provided the Terminal warning against better knowledge. Not a terribly likely scenario, IMHO.

Enabling Trim on Macs that are not your own, against an explicit warning of data loss, is irresponsible.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby Phil O » Fri Jul 15, 2016 9:06 am

mikehalloran wrote:Every Apple engineer I know recommends the Samsung 850 EVO and enabling TRIM.
I'm thinking of getting one of these. Any thoughts on EVO vs Pro?

(sorry if I'm getting a little off topic)
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby HCMarkus » Fri Jul 15, 2016 10:02 am

stratology wrote:Not a terribly likely scenario, IMHO.

It is if Apple doesn't want to have to deal with customers' third-party SSD issues.

IMO, NOT enabling Trim is irresponsible!

Phil O wrote:I'm thinking of getting one of these (Samsung 850). Any thoughts on EVO vs Pro

The difference between the EVO and Pro is TLC v MLC:

https://en.wikipedia.org/wiki/Multi-level_cell

MLC is inherently more robust, but in the interest of cost savings, I've got two 850 EVOs running now Phil. With 3-D NAND technology, the cell size is large. I'm feeling pretty confident about the 850 EVO series, and when you take a look at the endurance ratings, I think only the 4k video editors will have anything to worry about.

http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead
Note the EVO drive in the above test is the 840, not the much-improved 850.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby Phil O » Fri Jul 15, 2016 12:06 pm

Thanks. I've been leaning toward the 850 EVO.
DP 9.02, Mac Pro 2.66 quad[1,1] (6 Gig RAM), Mac Pro 2.8 octo[3,1], (12 Gig RAM), OS 10.6.8/10.11.6, two MOTU 828s, Apogee Rosetta 800, UAD-1e, UAD-2, a truckload of outboard gear and plug-ins, and a partridge in a pear tree.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Fri Jul 15, 2016 3:50 pm

HCMarkus wrote:IMO, NOT enabling Trim is irresponsible!


You're funny.

Enabling TRIM provides a minuscule performance improvement on disks that have lots of free space. Zero improvement on disks that are filled with data.

The only actual real world advantage is imaginary geek cred for the guy who enables TRIM via Terminal.
Risking data loss for that is a little sad.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby HCMarkus » Fri Jul 15, 2016 10:46 pm

stratology wrote:
HCMarkus wrote:IMO, NOT enabling Trim is irresponsible!


You're funny.

Enabling TRIM provides a minuscule performance improvement on disks that have lots of free space. Zero improvement on disks that are filled with data.

I think you're wrong about that. But I am happy to be funny! :)

Trim is not so much about performance as it is about minimizing write amplification, which shortens SSD NAND life and will ultimately impact performance as the drive is filled. SSDs have to maintain a degree of free space to function. This is accomplished by manufacturer-provided spare area that is inaccessible to the user. To be safe, some (possibly funny) people advise against filling SSDs to the limit, as the potential for write amplification increases.

Let's see what Wiki has to say about Trim:

The TRIM command is designed to enable the operating system to notify the SSD which pages no longer contain valid data due to erases either by the user or operating system itself. During a delete operation, the OS will mark the sectors as free for new data and send a TRIM command to the SSD to mark them as not containing valid data. After that the SSD knows not to preserve the contents of the block when writing a page, resulting in less write amplification with fewer writes to the flash, higher write speed, and increased drive life.

But you and I know this is completely false, and that Trim is just for geeks who, shunning risky sexual behavior (perhaps a different kind of Trim), feel obligated to take great risks with their and others' data.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Sat Jul 16, 2016 8:48 am

Bottom line:

I recommend to take Apple's warning seriously, because ignoring it can cause data loss (that may not be immediately obvious).

Others here suggest to ignore Apple's warning, because they think they know better, and don't mind risking data loss of their own and others' disks.



All the details about what TRIM does and does not do in general are completely irrelevant. It's about the behaviour of Apple's TRIM implementation for HFS+. TRIM is disabled by default for a reason.



Apple has announced that they are actively developing a new filesystem (APFS, optimised for Flash/SSD) that will replace HFS+ ( which is optimised for hard disks) in the future, and that APFS will natively support TRIM for 3rd party storage devices.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby Phil O » Sat Jul 16, 2016 9:59 am

I don't know. Apple's warning sounds a lot like a legal CYA statement. I've been using trim on my ssd for over a year now and everything is sailing along fine. ANY storage device is subject to failure and failure to backup is just asking for trouble. So •••• happens. But as far as I can tell trim isn't causing any problems on my system.

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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby stratology » Sat Jul 16, 2016 11:04 am

Phil O wrote:I don't know.


Exactly.

It can mean that
- in your specific case everything is indeed ok
- some files you never use are damaged
- metadata are damaged and you haven't noticed it
- possible issues, like app crashes, any kind of performance issues, etc., may have been incorrectly attributed to other causes



The point that this is a legal statement makes no sense.

As soon as you use any 3rd party disk, regardless of whether TRIM is enabled or not, Apple has no responsibility whatsoever, and does not support it. If you call Apple support with an issue that you have with an internal Samsung disk, or an external WD disk, AppleCare will suggest that you call the manufacturer of the product. This is true even if the product is purchased from Apple's website. Makes perfect sense. Why should AppleCare support Promise RAIDs, when Promise has their own support staff and the required expertise (to name just one example).

User data are always the users' responsibility, even with Apple's own disks.


"Use of this tool to enable TRIM may result in unintended data loss or data corruption. It should not be used in a commercial operating environment or with important data" is a pretty clear technical statement. The TRIM command line tool is provided in an (quote) 'as is' state, which means, it may or may not work correctly, feel free to experiment with it, e.g. on an external disk with no critical data.
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Re: Yosemite, Trim Enabler, NV RAM reset & Safe Boot etc.

Postby Phil O » Sat Jul 16, 2016 11:45 am

Didn't mean to turn this into an argument. I was just offering some anecdotal evidence, and the fact that there's a whole lot of legal speak in Apple's warning. Chill dude. We're all cool here. 8)
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