[Linux-cluster] Split-brain with DRBD active-active + RHCS

[jayesh.shinde]

Hi All ,

Just want mention one point. I am using Ext3 filesystem in below setup.

Regards
Jayesh Shinde


On 03/15/2011 05:43 PM, jayesh.shinde wrote:
> Hi All ,
>
> I don't have SAN with me , so I want to build the 2 node DRBD active 
> active for mysql & http  resource ( i.e /dev/drbd2 & /dev/drbd3 in my 
> case) with RHCS .
>
> I configured the require setup from 
> http://sourceware.org/cluster/wiki/DRBD_Cookbook and from DRDB links.
>
> From last 1 week I am testing the same scenario in 2 XEN vms with 
> kenel  2.6.18-128.el5xen , Every thing is working fine , like mysql 
> and http services move from one server to other etc... But not working 
> correctly when it get fence ( i.e when n/w fail on of the node).
>
> *I am facing the split-brain problem. * I search a lot in google and 
> mailling list but don't found the proper correct solution and suggestion.
>
> For Fence testing  I am doing following.
> ================================
> 1) On node1 http service is running with /dev/drbd2
> 2) On node2 mysql service is runing with /dev/drbd3
>     At this movement the DRBD primary-primary status is working correctly.
> 3) Now On node2 When I stop n/w service manually by "service network 
> stop"  then within 3-5 sec.  node2 get fence properly and mysql 
> service get switch on node1 properly.
> 4) After fencing when node2 come up , then I am facing the DRBD 
> split-brain issue with node1 and node2.
>
> My questions :--
> ==========
> 1) Why DRBD Split brain is not coming when I reboot or shutdown or 
> destroy the machine by xm command
>     i.e  "xm reboot <node1/node2>"   OR         xm shutdown 
> <node1/node2>  OR      xm destroy <node/node2>
>
> 2) Why the DRBD split brain issue come at the time of fencing node only ?
>
> 3) Is the combination of DRBD active-active + RHCS is stable ? and 
> workable solution
>     Because one of the below mailling list I found it's workable solution
> http://www.gossamer-threads.com/lists/drbd/users/20467#20467
>
> 4) In fencing Is there any extra setting require for such combination  ?
> 5) Do I need to use any custom fencing logic ?
>
> 6) Any one using such "*DRBD active-active + RHCS*"  setup in Live 
> without split brain issue ?
>
> Please guide and suggest on the same.
>
> Regards
> Jayesh Shinde
>
>

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