Poor performance on HGST hard disk on Mac OS

Discussion in 'iMac' started by potato.hk, Jul 5, 2017.

  1. potato.hk, Jul 5, 2017
    Last edited: Jul 5, 2017

    potato.hk macrumors newbie

    Joined:
    Jul 22, 2009
    #1
    I installed an Intel SSD (INTEL SSDSC2BP480G4) and replaced original hard disk with HGST
    HUS726060ALE610 on my iMac (27-inch, Mid 2010).

    Since I use SSD for system and the HGST hard disk for data backup. I did not pay attention to performance of HGST hard disk before.

    Recently, I want to build Android's AOSP on my iMAC. It requires to download over 100G data from repo to hard disk. I noticed that the speed was very slow. Then I ran black magic speed test on HGST hard disk and I found that the read/write speed was only 20MB/s. I double checked it with dd command and re-confirmed the performance issue.

    I did googling on it and I doubted it might be hardware issue or cable issue.

    Before I did any change, I boot my iMac with Ubuntu 16.04. I ran gnome-disks to check its performance and, surprising, it can reach 160-180MB/s. I couldn't believe it. I checked it again with "dd" command and copy large file as I did on Mac OS. The performance on Linux is constant and it is about 180MB/s.

    I rebooted it to Mac OS (no hardware change) and re-tested it. The performance of HGST hard disk was fall back to 20MB/s.

    It looks that it is a software (or firmware) issue and I wonder if anyone may have any suggestion on it.
     
  2. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #2
    What is the interface from the HGST HUS726060ALE610 to the 2010 iMac? Is it Firewire 800 or USB 2.0 or what?

    20 MB/sec sounds like a USB 2.0 rate. The 2010 iMac 27 had only USB 2.0 and FireWire 800. Is it possible that Ubuntu is using Firewire and macOS is using USB 2.0?
     
  3. potato.hk, Jul 5, 2017
    Last edited: Jul 5, 2017

    potato.hk thread starter macrumors newbie

    Joined:
    Jul 22, 2009
    #3
    --- Post Merged, Jul 5, 2017 ---
    It is connected by SATA. I replaced the original internal hard disk with this HGST hard disk. I have a Seagate external USB hard disk connected and USB 2.0 can reach over 30MB/s.

    I used OWC's kit for temperature sensor. On Mac OS, its reported temperature for hard disk is about 40-45 degrees ceslus. I also checked SMART report when I ran ubuntu. It has no error record and temperature never excess 50 degree for life time.
     
  4. potato.hk thread starter macrumors newbie

    Joined:
    Jul 22, 2009
    #4
    I don't know if Mac OS version is relevant. I am running High Sierra. I don't know if it happens before updating.
     
  5. joema2 macrumors 65816

    joema2

    Joined:
    Sep 3, 2013
    #5
    You replaced the internal HDD in your 2010 iMac 27 and now under the beta version of High Sierra it's giving slow performance, but you never tested the performance before. One possibility is it has always been slow but since you used it only for backup you never noticed it. Another possibility is the slowdown began with High Sierra beta, which is conceivable since it contains code for the new APFS file system. This might negatively affect performance of HFS+ volumes in some edge cases. E.g, there are various SATA transfer modes such as AHCI, command queuing, etc. If some driver change in High Sierra interrogated the SATA drive and reverted back to a slow transfer mode that could be responsible.

    The fact the drive gives good performance on Ubuntu indicates it's a software issue not hardware.

    If you have a bootable backup of an earlier macOS version you could try that. Another step is backing up your internal HDD then upgrading it to APFS. Maybe that would help. Otherwise you'll have to wait for the release version of High Sierra and maybe that would be faster.
     

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