slow SSD vs HDD

  • Hi all


    I just test speed of my disk and see SSD is slow.
    sdf is a SSD
    sde is a HDD


    result for sdf :

    Code
    ~# hdparm -t /dev/sdf
    /dev/sdf:
    Timing buffered disk reads: 236 MB in 3.08 seconds = 76.69 MB/sec
    root@nas:~# sudo hdparm -Tt /dev/sdf



    result for sde :

    Code
    hdparm -t /dev/sde
    /dev/sde:
    Timing buffered disk reads: 544 MB in 3.01 seconds = 180.73 MB/sec


    I dig a little and see that : SB7x0/SB8x0/SB9x0 SATA Controller [IDE mode]

    Do you kow if I can safely change IDE mode to AHCI in the bios ?


    thanks to all for your help



    result of dmesg | grep -i ahci

  • Yes and it is a much better option.

    I try to put ahci in my bios but when I do it I can't see the ssd.


    But I don't think this is the problem because the kernel take lead when debian boot.



    hum I will dig because I see 2 stanges thing : pata_atiixp


    strange I have just one sata controller on my MB I have 5x same seagate hdd and 1 ssd and i can see 2 'link' are in udma5 :


    Code
    sudo hdparm -I /dev/sd{a,b,c,d,e,f} | grep -i udma
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5 udma6
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5 udma6
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
    DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6

    hum waht 2 sata share an ATA ! like old ide device ! I will look in mobo option soon :


    Code
    ls -l /sys/block/sd* | sed -e 's@.*-> \.\..*/ata@/ata@' -e 's@/host@ @' -e 's@/target.*/@ @'
    /ata2 2 sda
    /ata2 2 sdb
    /ata3 1 sdc
    /ata4 3 sdd
    /ata5 4 sde
    /ata6 5 sdf

    ok I see on a bios " if you want boot on the 5 or 6 port sata" use ahci mode.
    the boot drive with OMV is on 6
    when I put ahci on port 5 and 6 the SSD drive is not listed in boot drive.


    I will change the sata port for the ssd to try.


    Do you know If I can change sata port drive without problem ?

  • I swap the ssd with a HDD
    All port is now on ahci


    but bad performance


    Code
    /dev/sda:
    Timing buffered disk reads: 238 MB in 3.06 seconds = 77.78 MB/sec


    this ssd is a PNY CS900 240GB SSD capable of sata 6 Gb/s but my Mb is just 3 Gb/s
    I don"t see new firmware ...



    I try some test on other disk


    sda : ssd
    sdb; hdd
    mdo : raid5 ( 5x hdd )


    mb ; M5A78L-M LX

  • I guess updating the kernel won't help since you are using the latest.

    Hi Ryecoaaron


    I just comeback with some information, Hdparm can use --offset


    look at that !


    without offset :


    Code
    hdparm -t --direct /dev/sda
    /dev/sda:
    Timing O_DIRECT disk reads: 290 MB in 3.01 seconds = 96.42 MB/sec



    with an offset of 1G :


    Code
    hdparm -t --direct --offset 1 /dev/sda
    /dev/sda:
    Timing O_DIRECT disk reads (offset 1 GB): 380 MB in 3.07 seconds = 123.63 MB/sec
    root@nas:~# hdparm -t --direct --offset 100 /dev/sda


    and with an offset of 100G


    Code
    hdparm -t --direct --offset 100 /dev/sda
    /dev/sda:
    Timing O_DIRECT disk reads (offset 100 GB): 664 MB in 3.00 seconds = 221.13 MB/sec
    root@nas:~#


    In my test I can see good speed start at 2G offset.


    It's strange because it's an SSD and I can read :


    --offset Offsets to given number of GiB (1024*1024*1024) when performing -t timings of device reads. Speed changes (about twice) along many mechanical drives. Usually the maximum is at the beginning, but not always. Solid-state drives (SSDs) should show similar timings regardless of offset.



    I add this :


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