[DRBD-user] Slow Read performance

[Maxim Ianoglo]

Hello,

Have two DELL PE R410, RAID 10 15K rpm Seagate SAS disks. Both servers are
connected via 1Gb link.

Testing performance with bonnie++.
On a RAW device  I get: ~240MB/s Read and ~390MB/s Write
On DRBD device with Secondary DRBD host connected: ~80MB/s Read and ~340MB/s
Write
On DRBD without Secondary DRBD host connected: ~245MB/s Read and ~340Write

Why I get so bad Read performance on DRBD device with Secondary host
connected ? Per documentation all reads should be made l

OS: CentOS 5.6 x86_64
DRBD: 8.3.10

Configuration:
============================================================
global {
  usage-count no;
}
resource repdata {
  protocol C;
  startup {
    wfc-timeout 0;
    degr-wfc-timeout 100;
  }
  disk {
    on-io-error detach;
    no-disk-barrier;
    no-disk-flushes;
  }
  net {
    max-buffers 8000;
    max-epoch-size 8000;
    unplug-watermark 16;
    sndbuf-size 0;
    cram-hmac-alg "sha1";
    shared-secret "secret";
    data-integrity-alg "crc32c";
  }
  syncer {
    cpu-mask 4095;
    rate 85M;
    verify-alg "crc32c";
    csums-alg "crc32c";
  }
  on secondary {
    device /dev/drbd0;
    disk /dev/sda9;
    address 10.10.1.141:7788;
    meta-disk internal;
  }
  on primary {
    device /dev/drbd0;
    disk /dev/sda8;
    address 10.10.1.142:7788;
    meta-disk internal;
  }
}
============================================================

Thank you
--
Maxim Ianoglo
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