[DRBD-user] active-active over long distance (split-brains)

Arnold Krille arnold at arnoldarts.de
Thu Feb 9 22:20:43 CET 2012

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


Hi,

On Thursday 09 February 2012 19:39:02 José Román Bilbao wrote:
> We have this scenario:
> - A datacenter
>  - 1 Server running kvm VMs:
>     * 1 Openfiler to distribute hard disk to other VMs (stores VMs and
> VMs's data) and other uses
>     * Other VMs...
>  - DRBD configured to replicate Openfiler's volumes as primary
> - B datacenter
>   - 1 Server running kvm as backup for center A failure events
>   - DRBD configured to serve as backup of Openfiler so VMs can be restarted
> in case of failure with updated data. It also works as primary.
> 
> Both centers are connected through wireless connections (500 Mb/s) which is
> good for our requirements. Nevertheless, there is a ping of 300 ms because
> of multiple routers in whithin...
> 
> We have been experiencing multiple split-brain situations and we don't know
> why... perhaps the link is down for a while but I don't understand the
> source of the problem as although they are primary-primary, one of the
> servers should never write to disk as all machines are kept on datacenter
> A, is this assumption right?, is this split-brain just "conceptual" telling
> that network was lost but no real uncoherences have appeared?. Under such
> asumption.. would it be ok to apply autorecover?.

If the second machine is completely passive and failover of the vms happens 
manually, why is the drbd in dual-primary (and thus C-sync)?
Would be much easier to have single-primary which resolves many of the split-
brain headaches, especially when the slave is only promoted by hand. And using 
B or even A sync will reduce your disks latency by 600ms (two times the 
300ms).

Good luck,

Arnold
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20120209/77218a9d/attachment.pgp>


More information about the drbd-user mailing list