Re: dd(1) performance when copiing a disk to another

From: Patrick Proniewski (patpro_at_patpro.net)
Date: 10/05/05

  • Next message: Robert Watson: "Re: Call for performance evaluation: net.isr.direct" 
    Date: Wed, 5 Oct 2005 19:30:24 +0200
To: freebsd-performance@freebsd.org

    Hi,

    thank you all for these interesting explanations.

    I've made some more tests with my disks :
    As you'll see, for block size greater than 64k, the HDD ad6 (hitachi)
    is the bottleneck.
    bs of 1m and 512k yield to best transfert rates between ad4 and ad6
    and using a pipe between to dd will lower the performance.

    best regards, and thank you again,

    Pat,

    #### /dev/zero to ad6

    # dd if=/dev/zero of=/dev/ad6 bs=1m count=1000
    1000+0 records in
    1000+0 records out
    1048576000 bytes transferred in 31.047655 secs (33773114 bytes/sec)

    # dd if=/dev/zero of=/dev/ad6 bs=8k count=128000
    128000+0 records in
    128000+0 records out
    1048576000 bytes transferred in 31.580223 secs (33203565 bytes/sec)

    #### ad4 (SATA150) to ad6 (SATA150)

    # dd if=/dev/ad4 of=/dev/ad6 bs=8k count=128000
    128000+0 records in
    128000+0 records out
    1048576000 bytes transferred in 50.916216 secs (20594146 bytes/sec)

    # dd if=/dev/ad4 of=/dev/ad6 bs=64k count=16000
    16000+0 records in
    16000+0 records out
    1048576000 bytes transferred in 30.925397 secs (33906630 bytes/sec)

    # dd if=/dev/ad4 of=/dev/ad6 bs=128k count=8000
    8000+0 records in
    8000+0 records out
    1048576000 bytes transferred in 31.462153 secs (33328170 bytes/sec)

    # dd if=/dev/ad4 of=/dev/ad6 bs=256k count=4000
    4000+0 records in
    4000+0 records out
    1048576000 bytes transferred in 30.819234 secs (34023428 bytes/sec)

    # dd if=/dev/ad4 of=/dev/ad6 bs=512k count=2000
    2000+0 records in
    2000+0 records out
    1048576000 bytes transferred in 30.589651 secs (34278783 bytes/sec)

    # dd if=/dev/ad4 of=/dev/ad6 bs=1m count=1000
    1000+0 records in
    1000+0 records out
    1048576000 bytes transferred in 30.660553 secs (34199514 bytes/sec)

    # dd if=/dev/ad4 bs=1m count=1000 | dd of=/dev/ad6 bs=1m
    1000+0 records in
    1000+0 records out
    1048576000 bytes transferred in 33.998716 secs (30841635 bytes/sec)
    0+16000 records in
    0+16000 records out
    1048576000 bytes transferred in 34.001099 secs (30839474 bytes/sec)

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