[DRBD-user] high load with drbd 0.7.23 and 2.6.17 kernel

[Petr Vyhnal]

So now I'm trying version 0.7.21 from Debian Etch recompiled to Sarge, 
but drbd disk is very slow in single mode also. I tested read speed with 
dd and the sda RAID5 device is about 45MB/s (not very good) but drbd 
device is only about 10MB/s which is extremely slow speed. I'm afraid 
that main problem is in RAID controller, but drbd performance isn't good 
as well.

Speed results:

mail:/etc# sync; time `dd if=/dev/drbd0 of=/dev/null bs=1M count=4096`
4096+0 records in
4096+0 records out
4294967296 bytes transferred in 375.754722 seconds (11430242 bytes/sec)

real    6m15.770s
user    0m0.004s
sys     0m7.416s
mail:/etc# sync; time `dd if=/dev/sda of=/dev/null bs=1M count=4096`
4096+0 records in
4096+0 records out
4294967296 bytes transferred in 91.180149 seconds (47104193 bytes/sec)

real    1m31.863s
user    0m0.016s
sys     0m6.892s

Running config:

global {
    minor-count 1;
    disable-ip-verification;
}

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

  startup {
    wfc-timeout  120;
    degr-wfc-timeout 60;
  }

  disk {
    on-io-error   detach;
  }

  net {
    max-buffers 8192;
    sndbuf-size 512k;
    max-epoch-size 8192;
    on-disconnect reconnect;
  }

  syncer {
    rate 125M;
    group 1;
    al-extents 1024;
  }

  on mail {
    device     /dev/drbd0;
    disk       /dev/sda8;
    address    10.0.0.1:7788;
    meta-disk  internal;
  }

  on mailbackup {
    device    /dev/drbd0;
    disk      /dev/sda8;
    address   10.0.0.2:7788;
    meta-disk internal;
  }
}


Leroy van Logchem napsal(a):
>> this kernel from 0.7.23 source. Should I downgrade to some previous
>> version of drbd to solve this problem? !
>>     
>
> No, the 0.7.23 is rock stable. Does your drbd.conf mention:
>
>
> resource drbd0 {
> <snip>
>     syncer {
>         rate             99M;
>     }
> <snip>
> }
>
>
>