8 ms·

Was surprised to hear OSX doesn't support TRIM. Does anyone know why? I was gettin all excited about getting a new SSD for my MBP, but now I'm not so sure...

js2 16y ago
Order a http://eshop.macsales.com/shop/internal_storage/Mercury_Extreme_SSD_Sandforce http://eshop.macsales.com/shop/internal_storage/Mercury_Extr... and don't worry about it.
- misterbwong 16y ago
  Just as a followup, this OWC mercury isn't the only one that does built in garbage collection. From what I can tell, most newer generation SSD's do it. While it's not as good as TRIM support, it's a reasonable approximation. As a side note for anyone else considering buying an SSD, there are rumors flying around that Intel is getting set to re-release their SSD line with a smaller micron next month. This should cut costs and increase speeds in time for the Christmas season.
Perceval 16y ago
The groundwork for TRIM has existed in OS X since 10.5. For some reason, Apple is waiting to enable it. http://www.ocztechnologyforum.com/forum/showthread.php?59299-Something-like-Wiper-for-OS-X#post409366 http://www.ocztechnologyforum.com/forum/showthread.php?59299... http://www.ocztechnologyforum.com/forum/showthread.php?59512-Wiper.exe-and-Boot-Camp-for-OS-X&p=410647#post410647 http://www.ocztechnologyforum.com/forum/showthread.php?59512... http://discussions.apple.com/thread.jspa?threadID=2213830 http://discussions.apple.com/thread.jspa?threadID=2213830 http://www.appleinsider.com/articles/10/06/14/apple_laying_groundwork_for_trim_support_in_future_ssd_based_macs.html http://www.appleinsider.com/articles/10/06/14/apple_laying_g...
- bryanh 16y ago
  Steve Jobs: "Thanks to everyone for coming today. Today is a big day. Today we release an update for Mac OS X that quadruples SSD performance and furthermore, all Macs will come standard with a SSD hybrid... etc..."
  - alanh 16y ago
    He wouldn’t use the word “today” three times in his first three sentences. Now, “amazing,” on the other hand… ;-)
arete 16y ago
AnandTech and other sites have mentioned that newer drives (Sandforce in particular) do background garbage collection which eliminates some of the need for TRIM - but does require idle time. I'd say go for the SSD. I just upgraded to a 240GB OCZ Vertex 2 and the speed boost is almost unbelievable.
- caf 16y ago
  Background garbage collection doesn't help so much if your drive doesn't know which logical blocks no longer contain active data - which is what TRIM is all about. (Filesystems historically never worried about informing floppy disks or hard disks about deleted sectors / blocks, because there was nothing useful those storage mediums could do with the information).
  - jeffffff 16y ago
    ssd's have spare blocks for extra life/wear leveling. ssd garbage collection can use LBA in combination with these spare blocks to always have cleared blocks.
    - caf 16y ago
      Sure, but it still has to waste time (and cell life) consolidating and moving about logical blocks that the filesystem no longer cares about.
      - jeffffff 16y ago
        GC only works while the drive is idle and should improve cell life drastically because you do a whole lot less read/modify/write cycles for small writes in the long run. Assuming a 256 GB drive with a write endurance of 1,000,000 cycles and a write speed of 200 MB/s, it would take on average 40 years to burn out the drive by sequentially overwriting its contents. The problem with read/modify/write is that if you are doing random writes of 4 KB with an erase block size of 512 KB at 50 MB/s, the effective internal write speed is 6 GB/s and you will burn out your drive in 1-2 years instead of 40. A full GC cycle is essentially a sequential rewrite of the drive. Let's say a full cycle frees up 16 GB, as 4 GB overprovisioning per 64 GB is standard. You can write 16 GB without any read/modify/writes, and for every 16 GB you write, you will have to do an additional 256 GB of writes for the GC cycle. That sounds awful, but compared to a bunch of read/modify/writes the drive life will go up by a factor of 8. The average write speed will also be higher. To avoid long pauses the GC only runs when the drive is idle, so for things like database servers trim is essential, but on a laptop/desktop GC is plenty good enough.
alanh 16y ago
As a commenter pointed out, it seems that TRIM is not needed, in practice, on OS X. http://www.bit-tech.net/hardware/apple/2010/07/01/mac-ssd-pe.. http://www.bit-tech.net/hardware/apple/2010/07/01/mac-ssd-pe.... As a MacBook Pro user who has had an SSD for a few months now — with a very full drive, frequent media file rotation, git repos, etc., I have not noticed any slowdown. And yes, it was worth it.
- jeffffff 16y ago
  that link is a bad test. they wrote 0's to the drive, which is bad because 1) empty nand flash contains all 1's and 2) writing 1's or 0's doesn't mark the blocks as cleared, you have to use secure erase

js2 16y ago

Order a http://eshop.macsales.com/shop/internal_storage/Mercury_Extreme_SSD_Sandforce http://eshop.macsales.com/shop/internal_storage/Mercury_Extr... and don't worry about it.

misterbwong 16y ago
Just as a followup, this OWC mercury isn't the only one that does built in garbage collection. From what I can tell, most newer generation SSD's do it. While it's not as good as TRIM support, it's a reasonable approximation. As a side note for anyone else considering buying an SSD, there are rumors flying around that Intel is getting set to re-release their SSD line with a smaller micron next month. This should cut costs and increase speeds in time for the Christmas season.

Perceval 16y ago

The groundwork for TRIM has existed in OS X since 10.5. For some reason, Apple is waiting to enable it. http://www.ocztechnologyforum.com/forum/showthread.php?59299-Something-like-Wiper-for-OS-X#post409366 http://www.ocztechnologyforum.com/forum/showthread.php?59299... http://www.ocztechnologyforum.com/forum/showthread.php?59512-Wiper.exe-and-Boot-Camp-for-OS-X&p=410647#post410647 http://www.ocztechnologyforum.com/forum/showthread.php?59512... http://discussions.apple.com/thread.jspa?threadID=2213830 http://discussions.apple.com/thread.jspa?threadID=2213830 http://www.appleinsider.com/articles/10/06/14/apple_laying_groundwork_for_trim_support_in_future_ssd_based_macs.html http://www.appleinsider.com/articles/10/06/14/apple_laying_g...

bryanh 16y ago
Steve Jobs: "Thanks to everyone for coming today. Today is a big day. Today we release an update for Mac OS X that quadruples SSD performance and furthermore, all Macs will come standard with a SSD hybrid... etc..."
- alanh 16y ago
  He wouldn’t use the word “today” three times in his first three sentences. Now, “amazing,” on the other hand… ;-)

arete 16y ago

AnandTech and other sites have mentioned that newer drives (Sandforce in particular) do background garbage collection which eliminates some of the need for TRIM - but does require idle time. I'd say go for the SSD. I just upgraded to a 240GB OCZ Vertex 2 and the speed boost is almost unbelievable.

caf 16y ago
Background garbage collection doesn't help so much if your drive doesn't know which logical blocks no longer contain active data - which is what TRIM is all about. (Filesystems historically never worried about informing floppy disks or hard disks about deleted sectors / blocks, because there was nothing useful those storage mediums could do with the information).
- jeffffff 16y ago
  ssd's have spare blocks for extra life/wear leveling. ssd garbage collection can use LBA in combination with these spare blocks to always have cleared blocks.
  - caf 16y ago
    Sure, but it still has to waste time (and cell life) consolidating and moving about logical blocks that the filesystem no longer cares about.
    - jeffffff 16y ago
      GC only works while the drive is idle and should improve cell life drastically because you do a whole lot less read/modify/write cycles for small writes in the long run. Assuming a 256 GB drive with a write endurance of 1,000,000 cycles and a write speed of 200 MB/s, it would take on average 40 years to burn out the drive by sequentially overwriting its contents. The problem with read/modify/write is that if you are doing random writes of 4 KB with an erase block size of 512 KB at 50 MB/s, the effective internal write speed is 6 GB/s and you will burn out your drive in 1-2 years instead of 40. A full GC cycle is essentially a sequential rewrite of the drive. Let's say a full cycle frees up 16 GB, as 4 GB overprovisioning per 64 GB is standard. You can write 16 GB without any read/modify/writes, and for every 16 GB you write, you will have to do an additional 256 GB of writes for the GC cycle. That sounds awful, but compared to a bunch of read/modify/writes the drive life will go up by a factor of 8. The average write speed will also be higher. To avoid long pauses the GC only runs when the drive is idle, so for things like database servers trim is essential, but on a laptop/desktop GC is plenty good enough.

alanh 16y ago

As a commenter pointed out, it seems that TRIM is not needed, in practice, on OS X. http://www.bit-tech.net/hardware/apple/2010/07/01/mac-ssd-pe.. http://www.bit-tech.net/hardware/apple/2010/07/01/mac-ssd-pe.... As a MacBook Pro user who has had an SSD for a few months now — with a very full drive, frequent media file rotation, git repos, etc., I have not noticed any slowdown. And yes, it was worth it.

jeffffff 16y ago
that link is a bad test. they wrote 0's to the drive, which is bad because 1) empty nand flash contains all 1's and 2) writing 1's or 0's doesn't mark the blocks as cleared, you have to use secure erase