I'm a newbie to SSDs and nearly complete beginner to TRIM, so this may sound a little bit dumb.

I found many articles (for example this one) and even more Internet sources that claims, that "TRIM support was introduced to make SSD work better". But today, I found this blog entry (in Polish, but most important quote is given in English), about TRIM on SSD for Mac computers, where we can read Kingston's technician saying that:

In fact, enabling TRIM could actually hurt the performance and reliability of your OWC SSD, rather than help it (…) Our in-house testing has also shown that the TRIM Enabler hack has proven to be unreliable. So bottom line, we highly recommend not using TRIM when using OWC SSDs; all you need is what’s already inside.

Article is dated seven days ago (May 22) so it sound like something new.

Is above claiming true? If so, why there are some many sources insisting on enabling TRIM and why Macs are so special, that for them specifically you shouldn't enable TRIM?

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    Trim is very useful if you have a SSD and want it to keep working at or near optimal levels over a longer period of time. However you do not need it. Even without TRIM a SSD will work fine in a regular desktop with regular usage. TRIM also needs to be supported by the OS, which is often not the case with OS X, which is why many Mac use a SSD which can clean up without the trim command. – Hennes May 29 '13 at 23:52
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    OSX does support TRIM but not for third party SSDs. It only supports the SSDs that Apple sells. – Conn Darcy May 30 '13 at 0:29
  • Would downvoter have enough courage to express in comment, what he or she doesn't like in this question? No... I don't think so... – trejder Dec 3 '13 at 21:46
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    Mac OS's are Unix derivatives, so you would expect Unix-like write buffering. Most people can live with that, depending upon the usage and the available memory. – mckenzm Apr 2 '16 at 21:23

The quote in the blog post you linked is from 2011 and it belongs to support engineers of one specific vendor talking about some potential issues with their drives and unofficial TRIM support hack at the time.

Personally I would enable TRIM and avoid that brand.


The flash chips used in silicon disks are subdivided into large blocks, each of which contains many 528-byte pages. It's not possible to erase pages individually; the devices are limited to erasing a block of data at a time. When software asks to write a 512-byte "disk sector", the drive will write the data to a new page and update some "index" data which tracks which physical page holds the latest version of each disk sector, after which the page which held the previous version will be available for recycling. If a all of the pages in a block have been superseded by pages elsewhere, the block may be safely erased. If, however, it's necessary to free up space when every block has at least some useful pages in it, it will be necessary to copy all of the useful pages from a block somewhere else before the block can be reused. If it later becomes necessary to recycle the blocks to which those pages had been copied, it will be necessary to copy the data yet again.

The purpose of "trim" is to indicate that a sector doesn't hold useful data, and thus there's no need to copy its contents to another sector if the block which contains it gets recycled. Unless the system was designed from the start to support "trim", however, marking a block as trimmed may cost just as much as writing it with useful data, and moving around information about which blocks are trimmed may not save much compared with copying actual data.

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