Slow SSD Speed after Mountain Lion Install

Discussion in 'OS X Mountain Lion (10.8)' started by februaries, Jul 31, 2012.

  1. februaries macrumors newbie

    Jul 31, 2012
    Hey everyone,

    I just clean installed Mountain Lion and noticed a reduced write speed in my SSD. I have the mid 2012 13" MBA and before ML, I was getting 350 MB/s write speed on Black Magic while running Lion. After a clean install, I noticed the write speed drop to 250 MB/s. I was wondering if anyone else was experiencing this? The one other thing I did do was install a bootcamp partition, though I dunno if that would effect the write speed on my Mac partition.
  2. kodeman53 macrumors 65816

    May 4, 2012
    Be prepared to be pummeled by the 'Clean Installs Fixes All Problems and Makes Everything Snappier' cult. :D

    I don't see the connection to Bootcamp either.
  3. ronnyweasle macrumors newbie

    Jul 27, 2012
    I have a mid-2012 MBP with a Corsair Force 3 SSD, and my speeds dropped also after the ML upgrade.
  4. Dam355 macrumors newbie

    Nov 11, 2009
    Perth, Australia
    Di you guys fix the slowness?

    I have ML on my new SSD

    I have installed a Corsair Force 3 SSD drive and have tried the Black Magic speed test. The speed is pretty much half what it should be by the looks.

    How fast is everyones drives?
    SSD Drive - Force Series

    Write speed - 200MB/s
    Read speed - 230MB/s

    It is on a i5 Macbook pro 13" 2011
    SATAIII 6GB link speed.
    Trim enabled.

    Anyone else having slow drives?
  5. Krazy Bill macrumors 68030

    Krazy Bill

    Dec 21, 2011
    Same with my Crucial M4 after installing ML.

    Unfortunately, I didn't notice this speed loss until I put my Snow Leopard clone back on the SSD. I'll probably do a secure erase when I get around to it.
  6. Menneisyys2 macrumors 603

    Jun 7, 2011
    Clean ML install on a late 2009 MBP 17" with 2.8GHz C2D (SATA II).

    1. Vertex 4 256 GB (SSD OCZ Vertex-4 256Gb SATA-600 (VTX4-25SAT3-256G)) with firmware 1.3 (Trim enabled):

    read: around 250 Mbyte/s
    write: around 180 Mbyte/s

    2. WD 1000Gb 2.5" SATA WD10JPVT Scorpio 5400rpm in the CD bay:

    around 98 Mbyte/s in both directions
  7. SlCKB0Y macrumors 68040


    Feb 25, 2012
    Sydney, Australia
    My Crucial M4 is a little faster under ML.

    280MB/s write and more than 500MB/s read.
  8. WesCole macrumors 6502a

    Jul 1, 2010
    Something is wrong with those Vertex 4 speeds, I think. I have a Vertex 4 128GB attached via Thunderbolt to my iMac and I get ~350MB/sec write and ~360MB/sec read.
  9. Menneisyys2 macrumors 603

    Jun 7, 2011
    Yup, my Macbook is SATA II only; hence the decreased speed.
  10. WesCole macrumors 6502a

    Jul 1, 2010
    Well, that explain it. :)
  11. 50548 Guest

    Apr 17, 2005
    Currently in Switzerland
    And WHY do you have TRIM artificially enabled? If it's a SandForce SSD, it's NOT supposed to have TRIM enabled on fact, performance will suffer, as already demonstrated elsewhere.
  12. SlCKB0Y macrumors 68040


    Feb 25, 2012
    Sydney, Australia
    This has been debunked pretty much everywhere.... The are not the same thing. The sandforce garbage collection and trim are not mutually exclusive.

    When I say debunked I mean by people who have a clue...
  13. plucky duck macrumors 6502a

    Jan 5, 2012
    Mine is the same before and after ML. Getting 247MB/s write and 265MB/s read consistently using blackmagic under osx on 2011 Mac Air 11".

    Updated ML on iMac and same SSD performance, no change either.
  14. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    I think the jury is still out on this.

    OWC officially recommends against the TRIM hack on their Sandforce drives. There have been quite a few forums posts from Sandforce drive users have trouble after using the TRIM hack. Many have no trouble at all though.

    While at the same time, Apple is of course using TRIM on its 2012 portables with Sandforce controlled SSDs. Maybe different firmware? Who knows.

    I am not disputing the benefits of TRIM, but using the hack with Sandforce aftermarket drives seems a bit spotty at this point.
  15. 50548 Guest

    Apr 17, 2005
    Currently in Switzerland
    So now you, Sickboy, have more clue than companies like OWC? Thanks for the laugh. ;)
  16. jkmags macrumors member

    May 6, 2011
    Ive got an OWC Mercury Electra 6g SSD 240gb drive, I ran a clean install of Snow Leopard, installed all my apps then ran the Mountain Lion update. I ran the Black Magic Disk Speed Test in both Snow Leopard and right after the upgrade to ML and was getting ~300MB/s writes and ~500 MB/s Reads. Now a few weeks later I am getting around 250 MB/s Writes and 450 MB/s Reads. Not sure why its getting a little slower but Ill keep an eye on it to see if it continues to get worse. Maybe I installed an app thats hitting my OS drive, though when I turn on the Disk Activity monitor in Istat Menus 3 I dont see a lot of activity.
  17. 50548 Guest

    Apr 17, 2005
    Currently in Switzerland
    You are NOT using TRIM Enabler, are you? Because if you are, turn it off - it's probably the reason behind the slower speeds.
  18. jkmags macrumors member

    May 6, 2011
    I am not using TRIM enabler, from my understanding OWC does not recommend enabling TRIM on their drives. I guess the SandForce controller on their SSDs takes care of the "garbage collection" as they put it.
  19. jkmags macrumors member

    May 6, 2011
    oddly, I was over reading some comments at OWC and found this post from here ( )

    he does make some valid points but I am no expert with regards to this subject and will follow the ssd manufacturers advice (OWC),..

    Michael's post below:

    June 27, 2012 at 9:48 am
    I contacted Sandforce regarding to Trim or not to Trim – They gave me good insight into their process:

    Here is a background on TRIM and GC-

    First – they are separate and not to be considered the same!

    In flash memory, Garbage Collection (GC) is the process of relocating existing data, deleting stale data, and creating empty blocks for new data

    All SSDs have some form of GC – it is not an optional feature

    NAND flash cannot directly overwrite a page with data; it has to be first erased

    One full block of pages has to be erased, not just one page

    GC starts after each page has been written one time

    Valid data is consolidated and written into new blocks

    Invalid (replaced) data is ignored and gets erased

    Wear leveling mainly occurs during GC

    The OS tracks what files are present and what logical blocks are holding the files

    SSDs do not understand the file structure of an OS; they only track valid data locations reported by the OS

    When the OS deletes a file, it marks the file’s space in its logical table as free – It does not tell the drive anything

    When the OS writes a new file to the drive, it will eventually write to the previously used spaces in the table

    An SSD only knows data is no longer needed when the OS tells it to write to an address that already contains data

    How Trim Works -

    The OS sends a TRIM command at the point of file deletion
    The SSD marks the indicated locations as invalid data
    TRIM Features:
    ► Prevents GC on invalid data
    ► Increases the free space known to the SSD controller

    TRIM Benefits:
    ► Higher throughput – Faster host write speeds because less time writing for GC
    ► Improved endurance – Reduced writes to the flash

    Lower write amplification – Less data rewritten and more free space is available • TRIM does not generally work behind a RAID environment

    Sandforce has a patented technology called Durawrite. I assume that OWC assesses that Durawrite is better than TRIM and makes TRIM obsolete. I don’t agree. Sandforce does not agree, they recommend running Durawrite and TRIM together. (Kent Smith – Sr. Director of Corporate Marketing SandForce)

    Please see the linked chart from SandForce. –

    Free Space for GC equals higher performance.

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