Information Technology Reference
In-Depth Information
Troubleshooting NFS Connectivity
If you're having problems getting an NFS datastore to mount, the following list can help you trouble-
shoot the problem:
Can you ping the IP address of the NFS export from the ESXi host? (Use the Direct Console
User Interface [DCUI] to test connectivity from the ESXi host, or enable the ESXi shell and
use the vmkping command.)
◆
Is the physical cabling correct? Are the link lights showing a connected state on the physical
interfaces on the ESXi host, the Ethernet switches, and the NFS server?
◆
Are your VLANs confi gured correctly? If you've confi gured VLANs, have you properly confi g-
ured the same VLAN on the host, the switch, and the interface(s) that will be used on your
NFS server?
◆
Is your IP routing correct and functional? Have you properly confi gured the IP addresses of the
VMkernel port and the interface(s) that will be used on the NFS server? Are they on the same
subnet? If not, they should be. Although you can route NFS tra c, it's not a good idea because
routing adds signifi cant latency and isn't involved in a bet-the-business storage Ethernet net-
work. In addition, it's generally not recommended in vSphere environments.
◆
Is the NFS tra c being allowed through any fi rewalls? If the ping succeeds but you can't mount
the NFS export, check to see if NFS is being blocked by a fi rewall somewhere in the path. Again,
the general recommendation is to avoid fi rewalls in the midst of the data path wherever pos-
sible to avoid introducing additional latency.
◆
Are jumbo frames confi gured correctly? If you're using jumbo frames, have you confi gured
jumbo frames on the VMkernel port, the vSwitch or distributed vSwitch, all physical switches
along the data path, and the NFS server?
◆
Are you allowing the ESXi host root access to the NFS export?
◆
Unlike VMFS datastores in vSphere, you need to add the NFS datastore on each host in the
vSphere environment. Also, it's important to use consistent NFS properties (for example, a
consistent IP/domain name) as well as common datastore names; this is not enforced. VMware
provides a helpful reminder on the Name And Coni guration screen, which you can see in
Figure 6.50. In the vSphere 5.5 Web Client you now have the ability to add additional hosts to an
existing NFS datastore without needing the NFS server IP and folder. Simply right-click an NFS
datastore and select All vCenter Actions
➢
Mount Datastore To Additional Host.
After the NFS datastore is mounted, you can use it as you would any other datastore—you
can select it as a Storage vMotion source or destination, you can create virtual disks on it, or you
can map ISO images stored on an NFS datastore into a VM as a virtual CD/DVD drive.
As you can see, using NFS requires a simple series of steps, several fewer than using VMFS.
And yet, with the same level of care, planning, and attention to detail, you can create robust
NFS infrastructures that provide the same level of support as traditional block-based storage
infrastructures.
So far we've examined both block-based storage and NFS-based storage at the hypervisor
level. But what if you need a storage device presented directly to a VM, not a shared container,
as is the case with VMFS and NFS datastores? The next sections discuss some common VM-level
storage coni guration options.
