[DRBD-user] Unable to adjust syncer rate.

Dwight Hubbard dwight at dwighthubbard.com
Wed Jun 3 16:31:45 CEST 2009

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


I've noticed in my usage of DRBD if the rate exceeds the performance of the
network between the nodes the sync rate sucks.  Since rate is in bytes per
second instead of bits per second a rate of 500MB/s would need 10GB ethernet
and even 100MB/s would exceed the performance of GB Ethernet cards plugged
into a standard PCI bus.

You might want to run iperf with the -f M parameter to get the actual
performance of the sync network and use it to tune the rate values.

On Tue, Jun 2, 2009 at 4:56 PM, Sylvain Niles <sniles at slingmedia.com> wrote:

>  I have tried everything under the sun and I can’t get syncer to go faster
> that about 15Mbit/sec. Any hints would be greatly appreciated as these
> devices are greater than 300G and initial sync is taking forever at
> ~10-15M/sec.
>
>
>
> I’m running drbd82 and kmod-drbd82 (v8.2.6) on CentOS 5. Here’s the
> cleansed version of my drbd.conf:
>
>
>
> global {
>
>   usage-count no;
>
> }
>
> common {
>
>   protocol C;
>
> }
>
> resource mysql-01 {
>
>   syncer {
>
>   al-extents         3833;
>
>   rate 500M;
>
>   }
>
>   net       {
>
>                 max-buffers 8192;
>
>                 }
>
>   disk {
>
>   no-disk-flushes;
>
>   no-md-flushes;
>
>   }
>
>   on mysql1 {
>
>     device    /dev/drbd1;
>
>     disk      /dev/data1/mysql-01;
>
>     address   <IP>;
>
>     meta-disk internal;
>
>   }
>
>   on mysql2 {
>
>     device    /dev/drbd1;
>
>     disk      /dev/data1/mysql-01;
>
>     address  <IP>;
>
>     meta-disk internal;
>
>   }
>
> }
>
> resource mysql -02 {
>
>   syncer {
>
>   al-extents         3833;
>
>   rate 100M;
>
>   }
>
>   net       {
>
>                 max-buffers 8192;
>
>                 }
>
>   disk {
>
>   no-disk-flushes;
>
>   no-md-flushes;
>
>   }
>
>   on mysql1 {
>
>     device    /dev/drbd2;
>
>     disk      /dev/data1/mysql-02;
>
>     address  <IP>;
>
>     meta-disk internal;
>
>   }
>
>   on mysql2 {
>
>     device    /dev/drbd2;
>
>     disk      /dev/data1/mysql-02;
>
>     address   <IP>;
>
>     meta-disk internal;
>
>   }
>
> }
>
> resource mysql3 {
>
>     syncer {
>
>     al-extents       3833;
>
>     rate 100M;
>
>     }
>
>   net       {
>
>                 max-buffers 8192;
>
>                 }
>
>   disk {
>
>   no-disk-flushes;
>
>   no-md-flushes;
>
>   }
>
>   on mysql1 {
>
>     device              /dev/drbd3;
>
>     disk    /dev/data1/mysql-3;
>
>     address            <IP>;
>
>     meta-disk       internal;
>
>     }
>
>   on mysql2 {
>
>     device              /dev/drbd3;
>
>     disk    /dev/data1/mysql-3;
>
>     address            <IP>;
>
>     meta-disk       internal;
>
>     }
>
> }
>
>
>
> Thanks,
>
> Sylvain Niles
>
>
>
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>
>


-- 
Dwight Hubbard
Owner Effective Automation Solutions
Website: http://effectiveautomationsolutions.com
Blog: http://computing.dwighthubbard.info
Email: dwight at dwighthubbard.com
Phone: (503) 616-4493
Redhat Certified Engineer - RHCE #804007137224095
VMware Certified Professional - VCP #18529
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