External SSD trim?

Discussion in 'MacBook Pro' started by Calby, Feb 27, 2017.

  1. Calby macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #1
    Hi,
    How can I make the performance from my external SSD as good as possible?
    Is trim enabled on it?

    I did read somewhere that you should make free space of 30GB ( don't even make it a partion just leave 30GB) to maximum the performence is that correct?

    I'm running the mbp 2015 with sierra and the SSD is a Samsung T3 500GB with USB 3.1.
     
  2. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #2
    I think you'll have to force TRIM on. It isn't necessarily supported by the USB bridge chip in the SSD however. Not all bridge chips support TRIM.

    In terms of leaving space free, SSDs do perform better with some free space, but there's already a portion of the SSD that is "over provisioned" as it's called. This is how it is straight from the factory. It may be a conservative amount, and leaving a bit more free could potentially be beneficial still, but honestly, I'd say don't worry about it.
     
  3. Calby thread starter macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #3
    Ok so should I force trim on it or just leave it as it is?
     
  4. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #4
    Try to enable trimforce. I mean, it's not exactly going to harm, cause either it works or nothing happens.
     
  5. Calby thread starter macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #5
    Ok, but how do I know if it works or not?
    If trim works, do I still need to leave a "unpartion"?
     
  6. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #6
    It is not going to work. macOS does not support TRIM over USB.

    Either way, there is no need to worry about leaving free space. As @casperes1996 mentioned, the disk is already "over provisioned" to allow for this. You might notice a little speed drop if the drive gets close to full, but otherwise, don't sweat it.
     
  7. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #7
    I think you should be able to see if it's TRIM enabled through System Information, though not sure if it shows with USB connected disks.
    The free space and TRIM thing are things that are meant to compliment each other actually, but as mentioned before, and as @Weaselboy refers to, it's not something you ought to actively think about. Just use the drive, and the controller inside it will manage the rest.
     
  8. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #8
    It is not going to show because TRIM won't work over USB with macOS. There are some enclosures that support UASP and Windows can TRIM (sort of). Here is a copy pasta of an earlier post.

     
  9. xWhiplash macrumors 65816

    Joined:
    Oct 21, 2009
    #9
    TRIM nowadays is overrated. I have been running SSDs on my 2010 Mac Pro for years without TRIM enabled. Maybe on the cheapo drives it is an issue. But I have not encountered any issues on Crucial or Samsung SSDs running without TRIM for years.
     
  10. Calby thread starter macrumors 6502

    Calby

    Joined:
    Dec 30, 2015
    Location:
    Sweden, Gävle
    #10
    Ok, sounds good will install it tomorrow and hoping to have a good speed.
    Did read something about sat drive installation but I guess that if I need it macOS will install it to me or prompt me about it.

    How can I test the speed? According to Samsung it should bee 450mb/s / 450mb/s
     
  11. CoastalOR macrumors 68000

    CoastalOR

    Joined:
    Jan 19, 2015
    Location:
    Oregon, USA
    #11
  12. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #12
    Thanks for the information. I wasn't sure about this myself – D'you think we'll see better UASP support on macOS in future? I'm in the market for an enclosure in the near future, and had been looking for something that supports UASP, but if it bears no benefit on macOS and won't there's no point in limiting my search.

    I think you've misunderstood the point of TRIM. It's not that running without will cause issues or anything. It's just for optimising the speed of SSDs as they fill up. If you imagine you have a room. Throwing a box into the room can be done relatively fast, but once the room fills up, you have to start removing boxes, before you can throw in a new one. This takes slightly longer. But what if, when you remove a box from the room and don't replace it, you would still have to go in the room when you want to put another box in there, and go to the place where there previously was a box, and "remove" the already removed box to put a new one in there? You'd be wasting time. That's what TRIM avoids.
    If you wipe your SSDs entirely right now, and start using them, until they're full, they'll run at a specific speed. When they then get full, you'll see a slowdown - now, it isn't a fixed slowdown and depends on the drive, but let's just say 20%. Even if you remove data from the drive, this slowdown might still be there, due to TRIM not being active, sending commands to the drive about which blocks are safe to erase entirely, after the file link has been removed.

    I have no idea what you're talking about, but the drive should function perfectly fine with no software installed.

    There are loads of drive testing apps. I personally use BlackMagic as another user suggested, and it's a quick download from the App Store. I can also recommend ATTO, and you can also manually calculate it, by timing a file transfer
     
  13. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #13
    I have not read anything about that SCSI UNMAP command coming to macOS. I have read about the new APFS Mac file system coming, but nothing I have seen related to that mentions this SCSI command.

    I would still get a UASP enclosure though because they are usually faster.
     
  14. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #14
    Thanks!
    Also, I don't think that anything about the file system relates to UASP. I've already done some tests with APFS however, and it's a lovely file system. Can't wait to replace all HFS+ with it. Already rocking it fully on my iOS devices, and have used it for smaller images on on macOS, but that's not really fair since that's an APFS image inside HFS+
     
  15. Fishrrman macrumors G4

    Joined:
    Feb 20, 2009
    #15
    Weaselboy wrote:
    "It is not going to work. macOS does not support TRIM over USB."

    This is correct for USB3 Gen1, up through the 2015 product line of Macs, but...
    ...I've read reports (over at Macintouch.com, I believe) that with USB-c and USB3.1 Gen2, TRIM -has been- indicated as being active on a few external drives. At least while using Disk Utility's repair disk function, DU reports "unused blocks" are being TRIM'ed.

    Just a few reports so far, and perhaps those doing the reporting were misled by "what they saw".

    I'm wondering if the USB 3.1 Gen2 specs (perhaps incorporating improvements in UASP) now include the ability to send TRIM commands via USB?

    Can't say for certain, yet. More reports are needed.

    But I've posted this before, and will state my opinion again:
    For the overwhelming majority of USB3 drives connected to a Mac, the "lack of TRIM" will make NO DISCERNIBLE DIFFERENCE over the lifetime of the drive, so long as the user leaves a sufficient amount of "free space" available. I've used an "external booter" SSD connected vai USB3 for more than four years now, and it runs as well as when it was first connected. TRIM has never become an issue. YMMV.
     
  16. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #16
    A good drive without TRIM is better than a bad one with TRIM, but it's still nice to have. Wish I had hardware to test with, whether it's actually there on the USB 3.1 Gen 2 Macs.
     
  17. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #17
    I'm not seeing TRIM on my 2016 Touchbar 13" with a Samsung EVO in a USB-C UASP enclosure.
     
  18. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #18
    Can I ask about testing methodology? Not that I don't think you're competent in terms of testing it, but just in case there may be potential workaround options.
     
  19. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #19
    I'm just looking at the drive and enclosure in system report and it does not show TRIM.

    On a drive with TRIM Disk Util will show that unused blocks message @Fishrrman mentioned and I'm not seeing that either.
     
  20. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #20
    I assume you have run the trimforce command, right?
     
  21. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #21
    Yup
     
  22. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #22
    Well, there we go then. Unless there's something in the way of the enclosure, SSD, cable or whatever that I can't really see what should be, preventing it, it doesn't appear like TRIM is supported then. Bummer.
     
  23. Fishrrman, Feb 28, 2017
    Last edited: Feb 28, 2017

    Fishrrman macrumors G4

    Joined:
    Feb 20, 2009
    #23
    To all:
    See this post from macintouch.com:
    https://www.macintouch.com/forums/showthread.php?tid=799&pid=15537#pid15537
    ===
    I have much the same system as Ric describes, except I used the StarTech.com USB 3.1 Gen 2 (10 Gb/s) mSATA Drive Enclosure (SM21BMU31C3) in place of the Sabrent. I use this system as my boot and data drive at work and at home; I carry it back and forth in my shirt pocket.

    StarTech claims to support Trim on this USB-SATA enclosure: "If the OS issues a TRIM command, the command will be passed to the connected device."

    When I run Disk Utility (First Aid) on this device, it does include the line "Trimming unused blocks." after the normal checks. Anyone know more about this specific operation on a USB -> SATA connected SSD? Is this verification that the TRIM command has been run by the SSD's internal controller?

    My Blackmagic Disk Speed Test (5 GB) results from a USB 3.1 Gen 1 (5 Gb/s) port and using the 1TB Samsung 850 EVO M.2 SSD are:

    423.3 MB/s Read and 430.1 MB/s Write.
    ===
    Here is the product the macintouch poster above is commenting about:
    https://www.amazon.com/StarTech-com...intouchforums-20?&tag=macintouchforums-20
     
  24. casperes1996 macrumors 65816

    casperes1996

    Joined:
    Jan 26, 2014
    Location:
    Horsens, Denmark
    #24

    Honestly, I'm a bit confused at this point. It is definitely not confirmation that the controller received the TRIM commands and handled them, but to me, it does seem like confirmation that macOS tried issuing said command, and most likely they were processed correctly. But I wouldn't say it's certain. Though since Disk Utility didn't report an error message, I assume that's the green light in terms of it working?
     
  25. Weaselboy Moderator

    Weaselboy

    Staff Member

    Joined:
    Jan 23, 2005
    Location:
    California
    #25
    That same person posts this later in the thread, so I remain unconvinced. USB does not support the TRIM ATA command. Windows is doing this by issuing the SCSI UNMAP command to achieve the same effect, but it is not really using the TRIM command either.

     

Share This Page