More companies are now deploying VMware with IP based shared storage (NAS). NAS storage is cheaper than Fiber Channel (SAN) storage because there is no separate Fiber Channel (FC) based network to maintain. More importantly, IP based storage performance and stability are now comparable with FC based storage.
Other advantages of using IP based storage, specifically NFS, are thin provisioning, de-duplication, and the ease-of-backup-and-restore of virtual machines and files on a virtual disk via array based snapshots. In addition, IP based storage is easier to maintain.
VMware published a whitepaper on the best practices for running VMware vSphere on Network Attached Storage (NAS) using NFS. Following the best practices in deploying an NFS based storage is very important to obtain a stable and optimized VMware environment. Here are the important things to consider:
On the network side, the local area network (LAN) on which the NFS traffic will run needs to be designed with availability, downtime-avoidance, isolation, and failover:
1. NFS traffic should be on a separate physical LAN, or at least on a separate VLAN.
2. Use private (non-routable) IP addresses. This will also address a security concern since NFS traffic is not encrypted and NFS is mounted with root privileges on the VMware host.
3. Use redundancy by teaming the NICs on the VMware host, configuring LACP protocol, and using two LAN switches.
4. Use jumbo frames.
5. Use 10GB Ethernet.
On the storage array side, the storage controller must be redundant, in case the primary one fails. In addition,
1. Configure the NFS exports to be persistent. (e.g. exportfs –p)
2. Install the VAAI and other plug-in tools from the storage vendor. For instance, NetApp has the Virtual Storage Console (VSC) plug-in that can be installed on the vCenter.
3. Refer to the storage vendor best practices guide. For instance, NetApp and EMC published their own best practice whitepapers for using NFS on VMware.
On the VMware hosts, the following configuration should be implemented:
1. Use the same datastore name across all hosts.
2. Select “No” for NIC Teaming failback option. If there is some intermittent behavior in the network, this will prevent the flip-flopping of NIC cards being used.
3. If you increase the maximum number of concurrent mount points (from the default of 8), also increase Net.TcpipHeapSize as well. For instance, if 32 mount points are used, increase tcpip.Heapsize to 30MB.
4. Set the following VMware High Availability options: (NFS heartbeats are used to determine if an NFS volume is still available.)
NFS. Hearbeat.Frequency=12
NFS.Hearbeat.Timeout=5
NFS.Hearbeat.MaxFailure=10
When configured properly, IP based storage, specifically NFS, provides a very solid storage platform for VMware.