SSD Purchase: should I let lack of TRIM support influence my decision?

Discussion in 'MacBook Pro' started by KettyKrueger, Jul 29, 2009.

  1. KettyKrueger macrumors 6502a


    Feb 17, 2007
    Hi all,

    I've spent the best part of the day researching SSD drives, I'm wanting to pop one in my MBP.

    I've been looking at the OCZ Vertex and also the Intel X-25M Gen 2.

    I've set my heart on getting the OCZ but after spending a good hour on their forums, it seems that (like all other drives) there isn't a 'wiper' tool available for OSX.

    Should this affect my decision? No-one knows if Snow Leopard will support TRIM and I don't want to left with a drive that has lost most of it's umph after a few weeks.

    I don't claim to know all the details of TRIM (I'm a mere-mortal wanting faster performance), so please feel free to put my mind at ease :eek:

  2. geoffreak macrumors 68020


    Feb 8, 2008
    We don't even know of TRIM will actually provide real world longevity and speed increases yet.

    If you are worried, just use a HDD instead of a SSD.
  3. adamk77 macrumors 6502

    Jan 6, 2008
    It will take more than a few weeks for your drive to suffer from the performance degradations that you probably read about on the review sites. From what I understand, Intel has not been able to reproduce those conditions without putting the SSD through highly artificial tests. For normal use, you will be fine.

    I believe the X25 already has TRIM support in it (which will help to alleviate the problem some, but not totally), and it's highly likely that Snow Leopard will have them. But as I said, you don't need to worry too much about it. If your SSD does end up suffering from the problem, it will take you at least around 6 months to a year. You can take your drive out of your Mac and do a wipe on your PC if you're a glutton for pain :)

    Also, even after the drives are full and it starts suffering from slow downs, it does not affect read speeds but rather write speeds. And even then, it's still faster than a HDD.

    I'll be getting the X25 G2 as soon as it becomes available again in a heartbeat.
  4. Yorick Guest

    Maybe a bit off topic, but can you please explain to me why and how often you should use a wiper tool? And what the main advantage is?

    I've ordered a X25-M G2 160 GB, think I'll receive it tomorrow.

    Thanks a lot!
  5. fehhkk macrumors 6502a


    Jun 11, 2009
    Chicago, IL
    This is all done by OS Support and firmware in the SSD controller, so if it's not supported now, it will in the near future.
  6. KettyKrueger thread starter macrumors 6502a


    Feb 17, 2007
    Thanks for the replies guys.

    That's what the problem was, I didn't really know how much of a problem this was, in real day-to-day use. Adam, you've cleared things up for me, thanks.

    @Yorick; i'm not a pro or anything, but the chips on the SSD (the memory) perform better (faster) when they are 'fresh' (have been restored to their original state). Unfortunately, a wipe and reinstall doesn't help, neither does securely deleting your data.

    A guy over on the OCZ forums (I think he works for OCZ) created a simple wiper program (Windows only) called wiper.exe which does wipe/restore the chips to their former glory (actually, I think the program is only useful for the Vertex drive).

    Feel free to edit the above :eek:
  7. Grayer macrumors newbie

    Jul 26, 2009
    But when you do the wipe thing, do you lose the info? It would suck to have to do everything all over again every x amount of time...
  8. thejadedmonkey macrumors 604


    May 28, 2005
    Why wouldn't a simple format fix everything though?
  9. jdechko macrumors 68040

    Jul 1, 2004
    Little info on the TRIM command

    I'm not an expert on this by any means, but I think I've got it simplified down to this (maybe oversimplified, but close enough, and understandable).

    Quick Background:
    When you delete a file (either from an SSD or a HDD), you don't actually delete the data, but rather the pointer to that data. This is how you are sometimes able to recover deleted data, and why the "Secure Erase" option exists.

    Now, regarding the SSD and TRIM

    1) An SSD memory cell can only be written if it is empty (HDD can overwrite previously written sections of the disk).
    2) If the memory cell is not cleared, the freed space cannot be reclaimed. Therefore, the cell has to be rewritten as a "blank" cell in order to be used again.
    3) Currently (without TRIM) this operation happens just before the cell is to be reused (written with new data). This is why older drives exhibit the slow down only when writing. The old data has to be cleared and the new data has to be written, so basically you're doing twice the work in a write.
    4) The TRIM command will essentially move the clearing command from the beginning of the write to the end of the delete.

    In picture form we have this:
    Old way:
    Delete>**********ELAPSED TIME*******>Clear>Write

    New way:
    Delete>Clear>**********ELAPSED TIME*******>Write

    We are still performing the same steps, but in a different and more efficient way. The clear command will still take cycles, but it will be done in the background after a delete. The user won't see the reduction in speed right after the delete, where he would have seen a slowdown in the write speed later on.

    If I'm wrong or I'm missing something, please feel free to correct me.
  10. adamk77 macrumors 6502

    Jan 6, 2008
    Good info jdechko.

    I might be getting the terminology a bit mixed up, but SSD can only erase page at a time. Inside a page, there are 'x' number of blocks. You cannot just erase individual blocks inside a page. You will have to erase the entire page. Meaning, in order to erase a single block, you have to read that entire page into memory, erase the block, and then write that page back. So there is even more overhead associated with it.

    Grayer -- yes, you'll lose everything. You'll want to back up your machine in Time Machine.
  11. jdechko macrumors 68040

    Jul 1, 2004
    Well, I can't take all the credit. Most of the information was here and here.
  12. harshw macrumors member

    Feb 19, 2009
    TRIM is needed due to the way the Flash cells are erased and read. But drives like the OCZ Summit ( with new 18C firmware ) and OCZ Vertex ( with the 1.3 firmware and up ) support garbage collection that does pretty much the same thing, except in the drive controller. Intel's drive also does the same thing with the latest firmware.

    Hence with these drives, TRIM is not needed as much as it should be. ie using an SSD with garbage collection means the SSD will slowly but steadily recover its performance after heavy usage and there is no need to wipe the drive to recover it.

Share This Page