Unfortunately there's a collision between the SATA spec having implemented TRIM rather wrongly, such that it's not a queued command like read or write. So it means the IO queue needs to be cleared before trim is issued, and this behaves something like a cache flush and is with most SSDs resulting in a big performance hit. It really should be delayed to only be issued during idle time, but I don't know how Apple implements trim in either HFS or CoreStorage. So what Apple do is disable trim for the vast majority of products and enable it on their products, since they know how the firmware's garbage collection behaves, and maybe a handful of other devices.
I appreciate the clarity and depth of your explanation. Do you happen to have a link regarding the SATA spec?
I think Apple ought to have the equivalent of an fstrim command to be issued as part of periodic monthly task, for all SSDs. I haven't looked at those scripts lately, to see what they're running. But I'm not finding an fstrim on OS X 10.8.5 or a reference to a Darwin equivalent.
Is that the sort of command which a utility or user could issue on a monthly basis or would it have to be part of the Mac OS itself? Your mention of Darwin makes it sound as though the command's possible under Linux, but I don't like the idea of typing the same line command on a monthly, repetitive and potentially thoughtless basis. Boredom can engender human error.
On the Samsung SSD 830 I'm using, I no longer enable trim. When it was enabled, periodically I'd experience 5-10 second total hangs of the system, which I'm 80% convinced was related to trim and deleting files, but I can't say for certain this is causation vs just some kind of correlation.
I experienced that, too, both before and after enabling trim. Booting into single-user mode and using the "fsck -fy" prompt -- as detailed in an earlier post -- got rid of the delay instantly.
Trim Enabler seems to be working fine with my 840 Pro 512 in my MacPro 3.33 on Mavericks, the drive is mounted in a Velocity X2 PCI-e card.
On another note, when I check the profile of my PCIe SSD in my rMBP, it says yes to trim support. Does this mean I don't need Trim Enabler on my 13" because it is already implemented or is it just saying it will work?
Thanks for the report in your first paragraph. I'm glad that "Trim Enabler seems to be working fine" in Mavericks.
However, I had to read your entire post five times to make sure I understood you. The phrase, "when I check the profile of my PCIe SSD in my rMBP, it says yes to trim support" could mean many things, especially since "it says" could be modified by "my PCIe SSD" or "my rMBP," and "it says yes to trim support" is not what your System Report is actually telling you.
Because of the dangling modifier mentioned above, you could be interpreted as saying that your Retina MacBook Pro has agreed to marry its trim support.
Additionally, you've made the identity of the SSD vague by mentioning you have an 840 Pro "mounted in a PCI-e card" in the first paragraph and then referring to "my PCIe SSD in my rMBP" in the second. The 840 on the "PCI-e" card mentioned in the first paragraph seems to have no problems; in your second paragraph, your "PCIe SSD" seems to be reporting something else.
Unless someone is reading closely enough to notice that the apparent semantic difference between the drives being referred to is probably unintentional, they'll waste time trying to understand what you're talking about in an effort to help.
If you're not talking about two different drives on PCIe/-e cards, and you're expressing confusion as to whether "TRIM Support: Yes" in your system report and "Everything looks super" under Trim Enabler mean the same thing, then the answer is yes. They do.
Both things mean that trim support is enabled, but pay particular attention to the yes
in your System Report. Everyone who enables trim -- whether they use Trim Enabler or Grant Parnell's method -- is looking for exactly the System Report information you're wondering about. If the word after the colon is yes
, then trim support is working.
If one of your two SSDs on separate PCIe/-e cards somehow "says yes" in an entirely different way under a different menu in what could be a different solar system, then I can't help you, as I have no idea what any of that means.
But if the steps I'm about list below sound incredibly familiar, then trim is enabled on your 840 Pro:
In your System Report under "About This Mac," the details under SATA/SATA Express should read as follows:
"TRIM Support: Yes."
means that Trim support is enabled, not that it is merely possible.
Again: Trim Enabler and your System Report are saying the same thing.
I'm going to be out all day and won't be able to respond to this thread, but I hope that this reply answered your question.