How to Upgrade vSphere without PCF Downtime
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This topic describes how to upgrade the vSphere components that host your Pivotal Cloud Foundry (PCF) installation without service disruption.
At a bare minimum, vSphere contains the following components:
- vCenter Server
- one or more ESXi hosts
You cannot perform an in-place upgrade of vSphere without at least two ESXi hosts in your cluster.
If you do not meet this requirement (in other words, you have insufficient resources to evacuate an entire host), then you may experience PCF downtime during the upgrade.
To upgrade vSphere with only one ESXi host or without sufficient headroom capacity, you must reduce your PCF installation size. In other words, you can either reduce the number of Diego cells in your deployment or pause PCF VMs to make more capacity available. These actions can result in PCF downtime.
If you are running a PCF deployment as recommended by the base reference architecture for PCF on vSphere (recommended), then your vSphere installation should have the following components:
- One vCenter Server
- Three ESXi hosts per cluster
- Three or more clusters
- One (or HA pair) NSX Edge appliances
Note: Pivotal recommends having at least three ESXi hosts in your cluster to maintain PCF high availability during your upgrade.
For more information, see the Reference Architecture for Pivotal Cloud Foundry on vSphere.
To upgrade the vSphere management layer underneath PCF, perform the following steps:
For example, you might be upgrading vCenter 6.0 to vCenter 6.5.
For more information about how to upgrade vCenter, see Overview of the vCenter Server Upgrade Process in VMware documentation.
After a successful vCenter upgrade, upgrade your ESXi hosts one at a time.
Starting with the first ESXi host, perform the following steps:
Verify that your ESXi hosts have sufficient resources and headroom to evacuate the VM workload of a single ESXi host to the two remaining hosts.
Note: If you have enabled vSphere HA on your ESXi host, then each ESXi host should have sufficient headroom capacity since HA reserves 66% of available memory.
Use vMotion to move all the PCF VMs on the host you want to upgrade to the other ESXi hosts. vMotion places the VMs on the other hosts based on available capacity. For more information, see Migration with vMotion in VMware documentation.
Upgrade the evacuated ESXi host. For example, you may be upgrading from ESXi v6.0 to ESX v6.5. For instructions, see Upgrading ESXi Hosts in VMware documentation.
After successfully upgrading the first ESXi host, repeat the above steps for each remaining host one at a time. vSphere automatically rebalances all PCF VMs back onto the upgraded hosts via DRS after all the hosts are done.
If your PCF deployment lives on a network behind an Edge Services Gateway (ESG) as recommended by the reference architecture, then upgrade each ESG only after completing the upgrade of vCenter and your ESXi hosts.
When you upgrade an ESG on VMware NSX, you upgrade the NSX Manager software. This upgrade can cause some slight downtime, the amount of which depends on the number of ESGs you are using.
- If your deployment only has one ESG, you can expect a downtime of 5 minutes for network reconvergence.
- If your ESGs are deployed in HA, upgrade the first ESG. Then upgrade the second ESG. This upgrade results only in 15-20 seconds of downtime.
For more information, see the NSX Upgrade Guide in VMware documentation.