[DRBD-user] DRBD State Confusion

Milind Dumbare milind at linsyssoft.com
Wed Sep 20 09:22:40 CEST 2006

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


On Tue, 2006-09-19 at 13:03 +0200, Usman Ahmad wrote:
> Hi,
> When does the drbd at both machines decide to sync?
AFAIK in two cases 
	- when remote/local data needs to be invalidated
	- after network failure
> Is it always syncing in background?
	- Thats what DRBD is for
> Does it sync on change of metadisk?
Metadisk? If metadisk is changed you will have a new setup. So again
choice is yours wheather you want to invalidate remote/local data or
not?
> Does it sync when a shift of state occurs? Secondary->Primary etc. 
No. Why would it sync when secondary -> primary change? 
> 
> I read about the DRBD+ for more than two nodes operaiton, is it open
> source, free to use?
> 
> Usman 
> 
> On 9/18/06, Milind Dumbare <milind at linsyssoft.com> wrote:
>         On Mon, 2006-09-18 at 15:21 +0200, Usman Ahmad wrote:
>         > Hi,
>         >
>         > Thanx for the explanation. Just curious what "halt -f" does?
>         related
>         > to DRBD or is it a system command?
>         >
>         its halt command, nothing to do with DRBD. 
>         
>         > Regards
>         > Usman
>         >
>         > On 9/16/06, Tim Jackson <lists at timj.co.uk> wrote:
>         >         Usman Ahmad wrote:
>         >
>         >         Hi, it would be easier if you didn't top-post.
>         Thanks. 
>         >
>         >         > No, there is no firewall setup, but same question
>         again, it
>         >         may be
>         >         > stupid. How long does a drbd node wait for
>         changing the
>         >         other node to
>         >         > unknown state ( i guess this is done through
>         different
>         >         timeout
>         >         > parameters etc.), and if the other server comes
>         back up
>         >         again, is it
>         >         > changed normally or not? 
>         >
>         >         First, just in case it wasn't clear, DRBD doesn't
>         change the
>         >         status of
>         >         the *local* node; only an external program (e.g.
>         Heartbeat)
>         >         does that.
>         >         As for what it shows for the status of the *remote*
>         node, 
>         >         well, I
>         >         haven't read the code but it normally seems to me to
>         be pretty
>         >         fast.
>         >         Again, read the logs: if the local node is primary
>         (and writes
>         >         are 
>         >         taking place, I think), then you should start seeing
>         "ko"
>         >         warnings
>         >         quickly, and how long before the other node is
>         declared dead
>         >         depends on
>         >         the "ko-count" configuration option. You will see
>         all kinds of 
>         >         warnings
>         >         from DRBD when the nodes can't communicate. See also
>         my bug
>         >         report on
>         >         this list the other day though, about DRBD not
>         reporting a
>         >         transition of 
>         >         the remote node to "Unknown" status in the logs.
>         >
>         >         > on-degr-cmd "echo '!DRBD! pri on incon-degr' |
>         wall ; sleep
>         >         60 ; halt -f";
>         >         > halt -f? 
>         >
>         >         That's not directly related. This is what happens if
>         the
>         >         machine is
>         >         inconsistent and the cluster is degraded when DRBD
>         starts
>         >         (i.e. the
>         >         machine should be becoming primary, but it doesn't
>         have a full 
>         >         copy of
>         >         the data).
>         >
>         >         Tim
>         >         _______________________________________________
>         >         drbd-user mailing list
>         >         drbd-user at lists.linbit.com
>         >         http://lists.linbit.com/mailman/listinfo/drbd-user
>         >
>         >
>         >
>         > --
>         > Usman Ahmad Malik 
>         > _______________________________________________
>         > drbd-user mailing list
>         > drbd-user at lists.linbit.com
>         > http://lists.linbit.com/mailman/listinfo/drbd-user
>         --
>         "The world is divided into one group: those who start counting
>         at 0,
>         and those who don't."
>         
> 
> 
> 
> -- 
> Usman Ahmad Malik
-- 
Milind
"The world is divided into one group: those who start counting at 0,
and those who don't."




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