Slow Hard Drive

  • I'm having trouble with a couple of Seagate 4TB hard drives that seem to have inconsistent performance.


    Here's the results of running hdparm -t /dev/sde four times in a row;


    Timing buffered disk reads: 2 MB in 4.69 seconds = 436.56 kB/sec
    Timing buffered disk reads: 2 MB in 4.70 seconds = 436.05 kB/sec
    Timing buffered disk reads: 446 MB in 3.01 seconds = 148.21 MB/sec
    Timing buffered disk reads: 444 MB in 3.00 seconds = 147.94 MB/sec


    And the results for hdparm -t /dev/sdb;


    Timing buffered disk reads: 2 MB in 4.67 seconds = 438.46 kB/sec
    Timing buffered disk reads: 378 MB in 3.01 seconds = 125.77 MB/sec
    Timing buffered disk reads: 372 MB in 3.01 seconds = 123.73 MB/sec
    Timing buffered disk reads: 378 MB in 3.00 seconds = 125.88 MB/sec


    I believe inconsistent results from hdparm are not uncommon (hence why it's worth running several times). But I'm finding the slow performance is causing buffering while trying to watch movies/tv shows from my NAS. So the issue is more significant than just some fluctuations in readings. Also, both the drives are relatively new and bought from two completely different sources and have no bad sectors. It strikes me as strangely co-incidental that they are both Seagates, though... so I'm wondering if there is some kind of factory setting I need to change. I have a 4TB Western Digital Red, and it hasn't caused me any problems.

  • And for what it's worth, the output of hdparm -i


    hdparm -i /dev/sde


    /dev/sde:


    Model=ST4000DM000-1F2168, FwRev=CC52, SerialNo=W300DJ4W
    Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
    RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
    BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=off
    CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=7814037168
    IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
    PIO modes: pio0 pio1 pio2 pio3 pio4
    DMA modes: mdma0 mdma1 mdma2
    UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6
    AdvancedPM=yes: unknown setting WriteCache=disabled
    Drive conforms to: unknown: ATA/ATAPI-4,5,6,7


    * signifies the current active mode



    hdparm -i /dev/sdb


    /dev/sdb:


    Model=ST4000DM000-1F2168, FwRev=CC52, SerialNo=W30011TQ
    Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
    RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
    BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16
    CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=7814037168
    IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
    PIO modes: pio0 pio1 pio2 pio3 pio4
    DMA modes: mdma0 mdma1 mdma2
    UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 udma6
    AdvancedPM=yes: unknown setting WriteCache=disabled
    Drive conforms to: unknown: ATA/ATAPI-4,5,6,7


    * signifies the current active mode

  • The two drives are set up differently
    /dev/sde has MultSect=off and *udma6
    /dev/sdb has MultSect=16 and *udma5


    You can use hdparm to set these parameters alike for the two drives.
    In the console can type

    Code
    hdparm /deb/sdb -X udma6

    and

    Code
    hdparm /dev/sde -m 16


    This will set the same parameters for the /dev/sdb and the /dev/sde drives
    If you want to make these settings persistent across boot you can put the commands into the end of the /etc/rc.local file right before the "exit 0" command


    hdparm parameters: http://linux.die.net/man/8/hdparm

  • Also, hdparm with 300mb? Are you trying to fool yourself?


    Try a real benchmark like


    Code
    cd /media/UUIDofyourdrive/
    dd if=/dev/zero of=tempfile bs=1MB count=10000


    ^Write test


    Code
    dd of=/dev/zero if=tempfile bs=1MB count=10000


    ^read test


    Greetings
    David
    David

    "Well... lately this forum has become support for everything except omv" [...] "And is like someone is banning Google from their browsers"


    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

    Upload Logfile via WebGUI/CLI
    #openmediavault on freenode IRC | German & English | GMT+1
    Absolutely no Support via PM!


    I host parts of the omv-extras.org Repository, the OpenMediaVault Live Demo and the pre-built PXE Images. If you want you can take part and help covering the costs by having a look at my profile page.

  • I was simply using the default settings in hdparm.


    Anyway, using DD



    On the surface, these numbers seem reasonable. Am I missing something? When I used these drives to serve tv shows to my media player, I was getting constant buffering issues. I replaced the drives, and the problem disappeared.


    Could the issue have been related to partitioning? Since replacing the drives, I have re-partitioned them and re-formatted.

  • How were your drives setup before? Is this a single drive? Raid? Multiple partitions on one drive?


    Greetings
    David

    "Well... lately this forum has become support for everything except omv" [...] "And is like someone is banning Google from their browsers"


    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

    Upload Logfile via WebGUI/CLI
    #openmediavault on freenode IRC | German & English | GMT+1
    Absolutely no Support via PM!


    I host parts of the omv-extras.org Repository, the OpenMediaVault Live Demo and the pre-built PXE Images. If you want you can take part and help covering the costs by having a look at my profile page.

  • Both of them are 4TB seagate drives. I had them individually partitioned, each with a single ext4 partition. One was serving as a parity drive for snapraid and the other stored my ripped TV shows.


    I was concerned that, being 4TB drives, I hadn't partitioned them correctly... which is why I re-partitioned.


    FYI, here is the current partition information.


    gdisk /dev/sdb

    Code
    Partition GUID code: 0FC63DAF-8483-4772-8E79-3D69D8477DE4 (Linux filesystem)
    Partition unique GUID: 2AF31848-54D8-424A-9C74-A59271CB15D0
    First sector: 2048 (at 1024.0 KiB)
    Last sector: 7814037134 (at 3.6 TiB)
    Partition size: 7814035087 sectors (3.6 TiB)
    Attribute flags: 0000000000000000
    Partition name: 'Linux filesystem'


    /dev/sde

    Code
    Using 1
    Partition GUID code: 0FC63DAF-8483-4772-8E79-3D69D8477DE4 (Linux filesystem)
    Partition unique GUID: B6AFC3C7-4048-401A-9C8E-FB1585E4F579
    First sector: 2048 (at 1024.0 KiB)
    Last sector: 7814037134 (at 3.6 TiB)
    Partition size: 7814035087 sectors (3.6 TiB)
    Attribute flags: 0000000000000000
    Partition name: 'Test'
  • I think the speed is a bit low for this hard drives, the drives should go way beyond 130MB/s I think, at least on the early sectors.


    Nevertheless, this should not cause any stutter while you stream your media. You media only needs ~5MB/s, and thats for a 40MBit rate Blu Ray ISO!


    Greetings
    David

    "Well... lately this forum has become support for everything except omv" [...] "And is like someone is banning Google from their browsers"


    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

    Upload Logfile via WebGUI/CLI
    #openmediavault on freenode IRC | German & English | GMT+1
    Absolutely no Support via PM!


    I host parts of the omv-extras.org Repository, the OpenMediaVault Live Demo and the pre-built PXE Images. If you want you can take part and help covering the costs by having a look at my profile page.

  • I've never really taken much notice of HDD benchmarks, because as long as my NAS serves my media to my media player... then it's "fast enough". Mostly, the bottleneck is going to be the ethernet cable, or the wireless network. A quick google, and it seems that 130MB/s is fairly standard for my model seagate drives. One of them seems to be running at around 120MB/s, which I'll call "good enough". The other seems a bit slower at 100MB/s, but that could be to do with some hardware bottlenecks on the server (I'm running an HP N40L with unmodified BIOS). But as you point out... it's all kind of irrelevant really... because even blu ray doesn't need high speed read access.


    So I can only assume that either repartitioning the drive might have resolved the problem... or, it's unrelated to the hard drives...


    I think all I can really try now, is to shift a few high definition rips to these drives and try some further "real world" tests.

  • Real world test? Place your highest bitrate file onto the hard disks, access it (via plex? dlna? whatsoever...) and start the dd command above, maybe increase the count a bit. If then your video stays to play continuesly you should be fine. (Also check that you test the same hard drive, and not stream from one and write to the other ^^).


    PS: Don't forget to delete the 'tempfile' on your hard disks.


    Greetings
    David

    "Well... lately this forum has become support for everything except omv" [...] "And is like someone is banning Google from their browsers"


    Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.

    Upload Logfile via WebGUI/CLI
    #openmediavault on freenode IRC | German & English | GMT+1
    Absolutely no Support via PM!


    I host parts of the omv-extras.org Repository, the OpenMediaVault Live Demo and the pre-built PXE Images. If you want you can take part and help covering the costs by having a look at my profile page.

Participate now!

Don’t have an account yet? Register yourself now and be a part of our community!