[DRBD-user] RE: How to do partial re-sync?

Vic Berdin vic at digi.com.ph
Mon Aug 15 14:13:25 CEST 2005

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

Hi Paul,

My test with drbd is very basic: I simply populate my Primary with new files
just right after a full-sync. I repeated the full sync process by:

a. doing a `drbdsetup /dev/drbd/0 invalidate`) on the secondary node
b. then populated the (already mounted) primary source device with
additional data (note that I did not do anything with the Secondary Node
c. then did a `sync` on the Primary

While doing the above, I was hoping that there will (should) be some
activity on Secondary's HDD LED, as (I hoped) new data gets
auto-replicated/copied. But there was none.
Then after populating the Primary, I unmounted the source device, then
shifted status for both nodes (Primary bacame Secondary, abd vise-versa),
then mounted the device of the Secondary. Lo and behold... the changes
indeed, did not take effect.

I was able to try drbd-0.6.13 way back, and a test somewhat similar to the
above, resulted to my expected results: Data got auto-replicated on the
Secondary. However, this isn't what I saw on 0.7.11.

Here is my config for both nodes:

global {
    minor-count 1;
    dialog-refresh 1;

resource r0 {
  protocol C;
  incon-degr-cmd "/bin/echo '!DRBD! pri on incon-degr: Do something!'";

  startup { wfc-timeout 1; degr-wfc-timeout 1; }
  disk    { on-io-error detach; }
  net     { timeout 60; connect-int 10; ping-int 10; sndbuf-size 1M; }
  syncer  { rate 4M; group 1; al-extents 127; }
  on node1 {
    device /dev/drbd/0; disk /dev/hdc2; meta-disk /dev/hdc3[0];
  on node2 {
    device /dev/drbd/0; disk /dev/hdc2; meta-disk /dev/hdc3[0];

And here are the states after full-sync and when I populate the Primary:

version: 0.7.11 (api:77/proto:74)
SVN Revision: 1807 build by root at linuxmachine, 2005-08-12 10:20:57
 0: cs:Connected st:Primary/Secondary ld:Consistent
    ns:0 nr:19357632 dw:19357632 dr:0 al:0 bm:1182 lo:0 pe:0 ua:0 ap:0

version: 0.7.11 (api:77/proto:74)
SVN Revision: 1807 build by root at linuxmachine, 2005-08-12 10:20:57
 0: cs:Connected st:Secondary/Primary ld:Consistent
    ns:19357632 nr:0 dw:0 dr:19357632 al:0 bm:2364 lo:0 pe:0 ua:0 ap:0

> ------------------------------
> Message: 2
> Date: Mon, 15 Aug 2005 01:09:43 -0400
> From: "Paul Bennett" <paul-bennett at nc.rr.com>
> Subject: Re: [DRBD-user] How to do partial re-sync?
> To: "drbd-user at linbit.com" <drbd-user at linbit.com>
> Message-ID: <op.svi9yhmcx5hs1e at spacey>
> Content-Type: text/plain; format=flowed; delsp=yes;
> 	charset=iso-8859-15
> On Mon, 15 Aug 2005 01:00:44 -0400, Vic Berdin 
> <vic at digi.com.ph> wrote:
> > I just want drbd to
> > auto-update the secondary with the new chunks of data created on the
> > Primary. How do I do this?
> This is what DRBD does, automatically and all the time. It's 
> the whole  purpose of the program.
> Are you seeing something that makes you think the data *isn't* being  
> updated? (e.g. TCP/IP trace data showing no data was transferred)
> What else are you expecting DRBD to do?

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