How to automate (after a given SNMP event) the activation of a vfiler DR without facing a duplicate IP address issue ?
I'm looking for any solution or method to automate the the activation of a vfiler DR when an event occur ? The objective is to automatically activate a VFILER DR when the CIFS client or NFS client cannot access the source VFILER ?
it is not easy because if the source vfiler is not stopped, a duplicate IP adress will occur on the network. Besides even if the source filer is not reachable on the network we cannot stop the source VFILER, we can activate the VFILER DR. But in case, the source VFILER come back on the network we may have a duplicate IP adress which may induce an application downtime (ex: Oracle on NFS).
Part of activating the dr vfiler is to stop the primary vfiler. This is for more than your duplicate IP issue, this is also to avoid split-brain (i.e. both sides are accepting writes). It is a very bad practive to try and activate the secondary vfiler without shutting the primary vfiler down. I can not recommend doing this.
I agree with Adam... An edge case or test case for a d.r site though... we have a customer who wants to do this for D.R. testing without shutting down the source system... the D.R. site is behind a firewall and secured so no split brain issue... the options we came up with.. but Adam's point is the first thing to think of...no split brain and design the testing carefully..
1. vfiler dr allows you to have a different IP, nis and dns at the dr site... so setup the d.r. site with the different ips... the only issue here is if you really need the same ips on failover... then you have use "vfiler run vfilername setup -e"...for the interface change to the test addresses, then change back to the actual failover addresses. The only little issue there is that setup wacks the exports, hosts.equiv, and other files...but the /etc mirror will fix that... except the different ip, nis, dns which is updated with vfiler dr activate.
2. create flexclones of each vfiler volume, then manually create the vfiler using all the clone volumes... not too hard to do and source mirrors keep working..even though more typing...create the test vfiler with a different ip.
i found this option "« no-vfiler-ips » it is a parameter to set to the value "true" in maintenance mode.It should allow to avoid IP adress conflict when the filer starts up and try to start the source VFILER.
si whi thtis option, in case of a disaster or an HW failure of the filer, you can activate vfiler DR on the secondary site. When the filer is repaired, you can enter in maintenance mode and set this parameter to avoid IP conflict.