This document describes how Symantec supports Veritas Cluster File System when used inside a VMware guest OS.
Scope and Application
- Veritas Cluster File System by Symantec, versions 6.0 and higher
- Guest Operating Systems: Redhat and SUSE Linux versions supported by VMware
- Supported versions of VMware: vSphere 5.1 and higher
Veritas Cluster File System has two supported modes of operation when used inside a guest OS that is running on a VMware hypervisor.
Mode 1: CFS connected to external storage via RDM-P
When CFS is running in a guest OS and use of highly reliable SCSI-3 PGR keys for split-brain protection and data fencing is desired, CFS must be connected to a physical LUN that has been mapped to a virtual machine disk (vmdk) using the VMware raw disk mapping physical (RDMP) compatibility mode. This option provides full CFS high availability support for fast failover, split brain protection, and data fencing, but does not allow use of VMware snapshots, vMotion, or other VMware HA features. CFS snapshots, clones, deduplication, and other storage optimization features are fully supported in this configuration.
Mode 2: CFS connected to VMFS with the VMFS multi-writer flag enabled.
When CFS is running in a guest OS and you desire guest OS mobility via VMware vMotion, the guest OS must use a VMFS virtual machine disk (vmdk). Normally, VMFS prohibits multiple guest OSes from connecting to the same virtual disk, thus precluding use of that vmdk with a parallel file system such as CFS. However, by enabling a new VMFS option, multi-writer (VMware k/b article 1034165), an administrator can create a vmdk that can be read/written to by multiple guest OSes simultaneously.
Because VMFS does not allow CFS to see the SCSI-3 persistent group reservation (PGR) bit on the LUN, SCSI-based I/O fencing will not work. In order to use CFS with the VMFS multi-writer option, Coordination Point Servers (CPS) must be used for split-brain protection (See Symantec Storage Foundation Support documentation). However, it must be noted that (CPS) does not support data protection via fencing, so care must be taken to prevent inadvertent data corruption caused by a non-CFS guest OS writing to a vmdk. CFS snapshots, clones, deduplication, and other storage optimization features are fully supported in this configuration.
An array support library (ASL) is required to recognize the disk as VMware Virtual Disk. ASLs can be downloaded here: https://sort.symantec.com/asl