vCenter is a business critical service that when it goes down can cause substantial chaos, although VMs will happily keep running while it is down. Using VDI? Forget spinning up new VMs, or rebooting VMs. Using vCD? Forget doing anything while it’s down. HA? Yes that will keep working (for one failure in 4.x, and indefinitely in 5.0). So this session focused on various means to make vCenter highly available since it has no built-in means to be HA, so a little help is needed.
- Linked mode does NOTHING for HA. A little data is replicated between the various instances, but if one of the vCenters goes offline you can’t manage the hosts it was servicing.
- You really need to establish RTO and RPOs for vCenter so you know what to design for.
- Other infrastructure like AD, DNS and SQL are critical and must be available. Also remember that network connectivity must be maintained.
- The main options the speaker offered up as HA solutions are:
- Traditional backup and restore: Does your backup solution need vCenter to do restores? This is a manual recovery process and doesn’t help with planned downtime like OS patching. You need a DR plan in place. See VMware KB 1023985 for some tips.
- Cold Standby: Easy if SQL DB is local, RTO can be shorter, but a manual recovery process. Harder to do if physical.
- Windows Clustering: Not supported by VMware as vCenter is not cluster aware.
- VMware HA and APIs: Neverfail and Symantec offer clustering/HA products. These are incomplete as their process monitoring is very basic and does not cover all scenarios. Better than nothing, but far from complete. Fairly automated, compliments HA, and fairly easy.
- VMware vCenter heartbeat:
- Not the cheapest solution, but it is the most comprehensive
- Active/passive configuration, share nothing model
- Protects against OS, HW, application and network failures
- Can be triggered on performance degradation of vCenter
- Protects against planned and unplanned downtime
- Protects vCenter plug-ins, SQL databases (even if on separate server) and VUM
- Works across the LAN or WAN
- Limited to a 1:1 topology
The bottom line is if you want an automated and comprehensive vCenter protection mechanism you are really left with one option, vCenter Heartbeat. I did a quick evaluation of it a couple of years ago before it supported 64-bit operating systems and the GUI/installation had a lot of room for improvement. I haven’t tried newer releases, so I hope it feels more like an integrated product than the Neverfail engine bolted on to some VMware customizations.
