[DRBD-user] drbd slow I/O with lustre filesystem

Dam Thanh Tung tungdt at isds.vn
Thu Oct 1 04:08:54 CEST 2009


Hi everyone

I'm currently using drbd as a network RAID 1 solution with my devices using
lustre file system.

I worked well during 3 months, but for now, because of some problem with
lustre and our storage devices, we have to rebuild almost all of our storage
solution. And the problems we're encountering with drbd now is :

After synchronizing a couple of our disk, we reformat it with lustre file
system format and start copying our data to drbd disk, but its I/O wait is
too high ( about 25% ) and the copy speed from our web client to drbd device
is too slow, only about 13MB/s although we're using 1Gb Ethernet !!!

I tried using one disk ( without using drbd ) with lustre file system and
it's ok.

Here is my drbd.conf file :

global {
  usage-count yes;
}
common {
  protocol C;
}
resource r0 {
net {
    allow-two-primaries;
    after-sb-0pri discard-zero-changes;
    after-sb-1pri discard-secondary;
    after-sb-2pri disconnect;
  }
startup {
    become-primary-on both;
  }
syncer {
    rate 80M;
  }
handlers {
    split-brain "/usr/lib/drbd/notify-split-brain.sh root";
  }

 on OST4 {
    device    /dev/drbd4;
    disk      /dev/sdb;
    address   10.0.0.84:7789;
    meta-disk internal;
  }
  on OST5 {
    device    /dev/drbd4;
    disk      /dev/sdb;
    address   10.0.0.85:7789;
    meta-disk internal;
  }
}

resource r1 {
net {
    allow-two-primaries;
    after-sb-0pri discard-zero-changes;
    after-sb-1pri discard-secondary;
    after-sb-2pri disconnect;
  }
startup {
    become-primary-on both;
  }
syncer {
    rate 80M;
  }
handlers {
    split-brain "/usr/lib/drbd/notify-split-brain.sh root";
  }

  on OST4 {
    device    /dev/drbd5;
    disk      /dev/sdc;
    address   10.0.0.84:7788;
    meta-disk internal;
  }
  on OST5 {
    device    /dev/drbd5;
    disk      /dev/sdc;
    address   10.0.0.85:7788;
    meta-disk internal;
  }
}




Do you have any idea about my problem?

Hope you can give me the answer as soon as possbile

Many thanks
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