Samsung SSD speeds High Sierra

Discussion in 'macOS High Sierra (10.13)' started by Sg335man, Apr 16, 2018.

  1. Sg335man macrumors newbie

    Mar 13, 2018
    Northwich Cheshire UK
    Hello I recently upgraded the firmware on my 840 Pro 256 SSD, running in my MBP late 2011 17" Its 4yrs old. Most of that time 3rd party "Trim Enabler" has been used. Since upgrading to High Sierra 10.13.4 in Jan 2018 According to Blackmagic app I am now getting

    440 write and 510 read? It takes 20 secs to boot. No Trim enabled

    I also have an external 850 EVO 500gig via Thunderbolt 1 port. The drive is 18month old. Same Blackmagic test.

    285 write 383 read No Trim enabled

    What speeds should one get? Of cause the "Trim" debate goes on "speed v long jeopardy
  2. rbart macrumors regular


    Nov 3, 2013
    The two drives are connected with Thunderbolt ?
    If your 840pro is directly connected to SATA, that's why it is faster.
  3. Sg335man thread starter macrumors newbie

    Mar 13, 2018
    Northwich Cheshire UK
    Many thanks for your post. The 840 Pro is internal directly connected to the SATA bus. The 850 EVO is connected via Thunderbolt 1 port. The Pro is a faster drive anyway. I am just not sure what speed I should get out of newish EVO via Thunderbolt connection?
  4. treekram macrumors 68000

    Nov 9, 2015
    Honolulu HI
    Trim should not affect read speeds to the point where a TRIM'd disk read is faster than a un-TRIM'd disk read. Are you still using a 3rd-party TRIM enabler (or disabler, as the case may be)?

    I have a bunch of Blackmagic results from my different SSD's in different configurations. It would be tedious to enter them here and because I don't have a complete comparative set of data (same SSD in SATA, USB3, Thunderbolt; same model SSD in different capacities), the data may be misleading anyway. But to me, the write speed doesn't seem too bad, the read speed is slower that expected. I say that because my 850 Evo's (250GB) all don't have blazing write speeds with Blackmagic. I also have a Monster Digital (240GB) Thunderbolt SSD where the write speed is pretty comparable. On the other hand, my Evo's get near or over 500MB/sec read using SATA and my TB SSD gets near 500MB/sec read when connected to my 2014 Mini (TB2 port - should not make a difference as the SSD is TB1).

    What Thunderbolt enclosure do you use?

    If you want to look into the issue more, you should switch SSD's - put the 850 in the MBP and 840 in the TB enclosure. If you don't have benchmarks pre-High Sierra, you wouldn't be able to see if the OS makes a difference (I don't have High Sierra on any of my Macs yet).
  5. mmomega macrumors demi-god


    Dec 30, 2009
    DFW, TX
    What enclosure is your external drive installed in?

    I am just asking because I came across a situation where I had an external Thunderbolt enclosure and was getting speeds similar to what you are seeing, I had a Samsung 850 EVO 500GB drive and getting around 300MB/s read/write tops.

    After some crazy digging around I found out the sata controller in the enclosure was SATA2 speeds and not SATA3. So then it made perfect sense, the controller can only hit approx 300MB/s maxed out regardless of Thunderbolt.

    I also had another early Thunderbolt external that came with platter drives. I switched out and installed SSD's and I was only getting approximately 150 MBps max. I raid0 the drives and still right at 150Max. So you may see where this is going, I looked up the SATA controller of that external and the manufacturer decided to install a SATA1 controller chip in the external. So no matter what I put in that enclosure 150 max will be all I can get.

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