Restarting VMware vCenter Server causes loss of vSphere Flash Cache reservation values

Products

• VMware vSphere ESXi

Issue/Introduction

When running a VMware vSphere Flash Read Cache (VFRC) configuration in VMware vCenter Server 5.5 or 6.0, you experience one or more of these symptoms:

• When vCenter Server is restarted, vSphere Flash Read Cache reservation host configuration values are lost.
• Capacity for VFRC shows 0.00 GB free out of 0.00 GB.
• Missing VFRC host configurations can result in failures of some vCenter Server provisioning operations, such as DRS, user-initiated power on operations, or vMotion migration operations.
• In certain configurations, when attempting to power on a virtual machine, you see an error in the vSphere Web client similar to:
  
  DRS cannot find a host to power on or migrate the Virtual Machine. The available virtual flash resource ('0' bytes) is not sufficient
  
  
  

Environment

VMware vSphere ESXi 6.0
VMware vSphere ESXi 5.5

Cause

vCenter Server does not currently persist VFRC runtime information in the vCenter Server Database, hence this information is not available when the vCenter Server service starts. This information can be retrieved through a host sync from the host.

Resolution

To resolve this issue, upgrade to vCenter Server 6.0 Update 2 and configure the advanced option config.vpxd.PersistVFlashRuntimeInfo value True.

1. Download and upgrade to VMware vCenter Server 6.0 Update 2a, available at Support Documents and Downloads (broadcom.com).
   
   
2. Configure the advanced option config.vpxd.PersistVFlashRuntimeInfo value True:
   
   
   1. Login into the vSphere Web client.
      
      
   2. Right-click vCenter and click Manage.
      
      
   3. Select Advance Settings and click Edit.
      
      
   4. Add config.vpxd.PersistVFlashRuntimeInfo value True.
      
      
   Note: After upgrading to vCenter Server 6.0 Update 2a, if you are configuring vFRC for the first time in your environment, you need not restart any management agents.
   
   
3. Restart the host management agents (hostd followed by vpxa) by running this command:
   
   /etc/init.d/hostd restart
   /etc/init.d/vpxa restart

To work around this issue if you do not want to upgrade, ensure that the vSphere Flash Read Cache reservation values for the ESXi host(s) are synchronized with vCenter Server using one of these options:

1. Disconnect the ESXi host(s) that are configured for vSphere Flash Read Cache, from vCenter Server and then reconnect the host.
   
   
2. Restart the management agents on the affected ESXi host(s).
   
   /etc/init.d/hostd restart
   /etc/init.d/vpxa restart
   
   For more information, see Restarting the Management Agents on an ESXi or ESX host (1003490).