[DRBD-user] Question on drbdadm verify

Dominik Klein dominik.klein at googlemail.com
Sun Jul 3 08:54:37 CEST 2011

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

On 07/02/2011 03:37 PM, Lars Ellenberg wrote:
> On Fri, Jul 01, 2011 at 11:00:32PM +0200, Lionel Sausin wrote:
>> Hi,
>> My understanding is that "verify" has a source and a target - and then
>> when you resync, blocks will flow from the source to the target, so if
>> the source is corrupt you'll replicate that corruption.
>> Anyone please correct me if I'm wrong.
> Nope.
> The direction of the resync, once it happens,
> has nothing to do with the "direction" of the verify.
> The "diretion" of the verify is mostly an internal detail only,
> of not much practical relevance.
> Verify just compares checksums of blocks,
> and marks blocks as being "different": out-of-sync.
> Resync bases the decision on the direction on the UUIDs,
> so if you have a "classic" Primary/Secondary setup,
> with disk state "UpToDate" on the Primary,
> then the resync direction caused by disconnect/reconnect
> is always from Primary to Secondary.

Thanks a lot for this explanation. Makes sense. I couldn't find this 
information on the net, might be worth documenting.


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