[DRBD-user] out-of-sync based on AL

[Cristian Zamfir]

Hi,

I just figured out that this is happening only when I am detaching two 
primaries.
Switching from primary to secondary before detach does not produce any 
resync.

 From the man, "In case a primary node leaves the cluster unexpectedly  
the  areas  covered  by
the active set must be resynced upon rejoin of the failed node"

But in this case I am manually detaching so it is not an unexpected 
leave from a primary node.
Is this a bug or is it the intended behaviour?

Cheers,

Cristian


Cristian Zamfir wrote:
>
>
> Ross S. W. Walker wrote:
>>> -----Original Message-----
>>> From: drbd-user-bounces at lists.linbit.com 
>>> [mailto:drbd-user-bounces at lists.linbit.com] On Behalf Of Cristian 
>>> Zamfir
>>> Sent: Wednesday, February 14, 2007 12:52 PM
>>> To: drbd-user at lists.linbit.com
>>> Subject: [DRBD-user] out-of-sync based on AL
>>>
>>>
>>> Hi,
>>>
>>> I am trying to understand why the AL is marking 196MB as out of sync.
>>> I have two connected primaries A and B. After they are synced I 
>>> detach B. In the mean time, the disk on A is not used. I reconnect B 
>>> and the on disk bit map sees that no bytes are out-of-sync, but AL 
>>> marks 196MB as out-of-sync.
>>>
>>> In case I am misunderstandings something, can you please explain a 
>>> bit how the AL works?
>>>
>>> This is what dmesg says on node B:
>>>
>>>
>>> [11989.600828] drbd1: disk( UpToDate -> Diskless )
>>> [11994.007899] drbd1: disk( Diskless -> Attaching )
>>> [11994.040025] drbd1: Found 6 transactions (50 active extents) in 
>>> activity log.
>>> [11994.040067] drbd1: max_segment_size ( = BIO size ) = 32768
>>> [11994.050505] drbd1: reading of bitmap took 1 jiffies
>>> [11994.050759] drbd1: recounting of set bits took additional 0 jiffies
>>> [11994.050780] drbd1: 0 KB marked out-of-sync by on disk bit-map.
>>> [11994.050819] drbd1: Marked additional 196 MB as out-of-sync based 
>>> on AL.
>>> [11994.066857] drbd1: disk( Attaching -> Negotiating )
>>> [11994.066942] drbd1: Writing meta data super block now.
>>> [11994.067332] drbd1: conn( Connected -> WFBitMapT )
>>> [11994.067358] drbd1: Writing meta data super block now.
>>> [11994.079356] drbd1: conn( WFBitMapT -> WFSyncUUID )
>>> [11994.090853] drbd1: conn( WFSyncUUID -> SyncTarget ) disk( 
>>> Negotiating -> Inconsistent )
>>> [11994.090895] drbd1: Began resync as SyncTarget (will sync 200704 
>>> KB [50176 bits set]).
>>> [11994.090926] drbd1: Writing meta data super block now.
>>> [12014.611505] drbd1: Resync done (total 20 sec; paused 0 sec; 10032 
>>> K/sec)
>>> [12014.611562] drbd1: conn( SyncTarget -> Connected ) disk( 
>>> Inconsistent -> UpToDate )
>>> [12014.611601] drbd1: Writing meta data super block now.
>>>     
>>
>> Interesting, what method did you use to detach and which version are you
>> running?
>>
>> -Ross
>>
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>>   
> I use drbdadmin detach and drbdadmin attach.
> I checked out the latest svn trunk on Mon, 11 Dec 2006 and my kernel 
> is 2.6.16.29.
> I am using drbd on top of a 4GB LVM partition with an internal 
> metadata disk.
>
> resource "r1" {
>  protocol C;
>  startup {
>    wfc-timeout         0;  ## Infinite!
>    degr-wfc-timeout  120;  ## 2 minutes.
>  }
>  disk {
>    on-io-error detach;
>  }
>  net {
>    # timeout           60;
>    # connect-int       10;
>    # ping-int          10;
>    # max-buffers     2048;
>    # max-epoch-size  2048;
>   allow-two-primaries ;
>  }
>  syncer {
>    rate 10M;
>    al-extents 257;
>  }
>
>  on ramree {
>    device     /dev/drbd1;
>    disk       /dev/vgn/vm;
>    address    130.209.253.128:7789;
>    meta-disk  internal;
>  }
>
>  on rangatira {
>    device    /dev/drbd1;
>    disk      /dev/vgn/vm;
>    address   130.209.253.129:7789;
>    meta-disk internal;
>  }
> }
>
>
> Cheers,
>
> Cristian
>
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