[DRBD-user] drbd problem on linux software raid

Ove Thoresen othoresen at yayamedia.it
Mon Jul 24 12:00:57 CEST 2006

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I have a drbd (drbd 0.7.19) setup on Centos 3.7 with software raid
Everything is Ok but I have hundreds of messages of this type in the log 
file

Jul 24 11:49:31 mail01 kernel: raid5: switching cache buffer size, 4096 --> 512
Jul 24 11:49:31 mail01 kernel: raid5: switching cache buffer size, 512 --> 4096
Jul 24 11:49:31 mail01 kernel: raid5: switching cache buffer size, 4096 --> 512
Jul 24 11:49:31 mail01 kernel: raid5: switching cache buffer size, 512 --> 4096
Jul 24 11:49:31 mail01 kernel: raid5: switching cache buffer size, 0 --> 4096

The messages are much more frequent on the primary node, but occasionally I also see them on the secondary node

I understand that this continous switching reduces performance quite a lot.
Can anyone suggest why this is happening?

my drbd.conf file:

resource r0 {

  protocol C;
  incon-degr-cmd "echo '!DRBD! pri on incon-degr' | wall ; sleep 60 ; 
halt -f";

  startup {
    degr-wfc-timeout 15;    # 2 minutes.
  }

  disk {
    on-io-error   detach;
  }

  net {
    max-buffers     4096;
  }

  syncer {
    rate 70M;

    group 1;
    al-extents 257;
  }

  on mail01.domain.loc {
    device     /dev/drbd0;
    disk       /dev/md3;
    address    10.3.0.1:7788;
    meta-disk  internal;
  }

  on mail02.domain.loc {
    device    /dev/drbd0;
    disk      /dev/md3;
    address   10.3.0.2:7788;
    meta-disk internal;
  }
}
-- 
------------------------------------------------------------------------
/Ove Fredrik Thoresen /
<mailto:othoresen at yayamedia.it>othoresen at yayamedia dot it



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