There was a request from Rizwan to explain how NetBackup for VMware works. Several votes and comments later, I came to know about it from a technical support engineer who had pointed me to that post. We hear you loud and clear, we are looking into getting more details in NetBackup for VMware System Administrator’s Guide. While we wait for a formal documentation update, I thought I better write a set of blogs on what was requested by the community. So here it goes.
Let me not repeat what is already there in the manual. If you are new to NetBackup for VMware, I would strongly recommend going through NetBackup for VMware System Administrator's Guide for an introduction.
For this discussion let us assume that the NetBackup master server, media server and VMware backup host are three different systems. Also let us assume that the VMware backup host and VMware discovery host are the same system. The request was to provide a flow of communications for backups and restores. In order to get there, first we need to discuss virtual machine discovery as well.
NetBackup for VMware features two kinds of virtual machine discovery. The newer VMware Intelligent Policy (VIP) discovery and original browse and select discovery. The former creates a discovery job in activity monitor; hence let us discuss its process flow before getting into backup.
VMware Intelligent Policy Discovery: This game changing discovery method is part of Symantec’s V-Ray vision; a set of technologies to provide unique visibility into virtual machines. Your virtual machine protection strategy enters auto pilot mode with VIP. In the policy you are simply specifying selection criteria for what needs to be protected (e.g. all the virtual machines in data center X, all virtual machines in cluster Y, all virtual machines with RedHat Linux etc.). NetBackup automatically discovers the VMs matching the criteria and runs backups. How cool is that! Visibility matters! Let us go through a high level overview of the process flow for VIP discovery job in this blog.
- When backup window opens, NetBackup Policy Execution Manager (nbpem) on master server looks to see if there is a VM list xml file in its policy database (we will explain this later) to see if it can use the pre-existing list of virtual machines. If the xml file is present, it examines its age to see if a new one needs to be generated. Let us assume that the xml file is not present or it is older than the time interval specified in the policy attribute named “Reuse VM selection query results for”. Then a discovery job shows up in Activity Monitor.
- nbpem on master contacts NetBackup Client Service (nbcs) on media server*.
- nbcs on media server starts NetBackup Client Service (nbcs) on VMware backup host*.
- nbcs has a plug-in for VMware which gets loaded. VMware APIs for Data Protection (vADP) calls are implemented in this plug-in. NetBackup has credentials to access the vSphere host (vCenter or ESX/ESXi), it logs into the vSphere host and runs VM discovery based on the selection query given in the policy. The vSphere host returns an xml file with the results. This file may or may not be processed further by the plug-in based on the kind of query.
- nbcs returns the VM list xml file to master server through nbcs on media server*.
- nbpem on master server uses the xml file to generate the client list. The discovery job in Activity monitor moves to Done state.
- If the backup is due it is started by nbpem. The xml file persists in NetBackup database until its age exceeds the time specified in the policy attribute named “Reuse VM selection query results for”
*We assumed here that media server and VMware backup host are separate hosts. As NetBackup is an enterprise platform, there could be a firewall between NetBackup master server and VMware backup/discovery host. The nbcs on media server starts nbcs on VMware backup host on behalf of master server in this case. If the VMware backup host and media server are the same, NetBackup is smart enough to use a singe nbcs process.
VMware Intellgent Policy is availble in NetBackup 7.1 and NetBackup 5200 series appliances with software version 2.0.
Nuts and Bolts in NetBackup for VMware series continues here: