[DRBD-user] Performance issue

Sampo Blom sampo.blom at vsp.fi
Tue Aug 12 13:08:27 CEST 2008

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 two:


Intel Q6600 boxes with 4GB of RAM

8 x 750Gb (4,5TB RAID5EE, Adaptec 2820SA)

2 x 1Gbit Ethernet


eth0: LAN

eth1: DRBD SYNC (crosscable between machines)


/dev/sda2  ~4,5TB for DRBD


The problem is that, when I connect to an ftp/samba server on LAN (eth0)
and I start uploading a file. Transfer rate is about 20-40MB/s about
10-15 seconds, then it starts lagging, about 4-10MB/s. Transfer-rate
sleeps 0MB/s 5 seconds for example and all ftp transfers gets timeout.


I have monitored eth1 with iptraf, and it doesn't sync more that
6-10MB/s while drbd state is (cs:Connected st:Primary/Secondary
ds:UpToDate/UpToDate C r---).

When drbd does sync while other end has been offline for a while... sync
rate is about 20-25MB/s.



Ubuntu 8.04 Server

kernel : 2.6.24-19-server

drbd version: 8.0.11








global {

    usage-count no;


common {

  syncer { rate 33M; }


resource r0 {

  protocol C;

  handlers {

    pri-on-incon-degr "echo o > /proc/sysrq-trigger ; halt -f";

    pri-lost-after-sb "echo o > /proc/sysrq-trigger ; halt -f";

    local-io-error "echo o > /proc/sysrq-trigger ; halt -f";


startup {

    degr-wfc-timeout 120;    # 2 minutes.


disk {

    on-io-error   detach;


  net {

max-buffers 8192;

unplug-watermark 8192;

max-epoch-size 2048;


syncer {

    rate 33M;

    al-extents 2570;



  on storage1 {

    device     /dev/drbd0;

    disk       /dev/sda2;


    flexible-meta-disk  internal;



  on storage2 {

    device     /dev/drbd0;

    disk       /dev/sda2;


    flexible-meta-disk  internal;







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