I/O Filter Guidelines and Best Practices

When you use I/O filters in your environment, follow specific guidelines and best practices.

• Because I/O filters are datastore-agnostic, all types of datastores, including VMFS, NFS, Virtual Volumes, and vSAN, are compatible with I/O filters.
• I/O filters support RDMs in virtual compatibility mode. No support is provided to RDMs in physical compatibility mode.
• Flash Read Cache and caching I/O filters are mutually exclusive because both functionalities use the virtual flash resource on the host. You cannot enable Flash Read Cache on a virtual disk with the cache I/O filters. Similarly, if a virtual machine has Flash Read Cache configured, it cannot use the cache I/O filters.
• You cannot change or assign the I/O filter policy while migrating or cloning a virtual machine. You can change the policy after you complete the migration or cloning.
• When you clone or migrate a virtual machine with I/O filter policy from one host to another, make sure that the destination host has a compatible filter installed. This requirement applies to migrations initiated by an administrator or by such functionalities as HA or DRS.
• When you convert a template to a virtual machine, and the template is configured with I/O filter policy, the destination host must have the compatible I/O filter installed.
• If you use vCenter Site Recovery Manager to replicate virtual disks, the resulting disks on the recovery site do not have the I/O filter policies. You must create the I/O filter policies in the recovery site and reattach them to the replicated disks.
• You can attach an encryption I/O filter to a new virtual disk when you create a virtual machine. You cannot attach the encryption filter to an existing virtual disk.
• If your virtual machine has a snapshot tree associated with it, you cannot add, change, or remove the I/O filter policy for the virtual machine.

For information about troubleshooting I/O filters, see the vSphere Troubleshooting documentation.