Tag Archive for NFS

Troubleshooting NFS Mounting and Permission issues

February 13, 2013 Objective 6 Advanced Troubleshooting No comments

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What is NFS?

ESXi hosts can access a designated NFS volume located on a NAS (Network Attached Storage) server, can mount the volume, and can use it for its storage needs. You can use NFS volumes to store and boot virtual machines in the same way that you use VMFS datastores.

NAS stores virtual machine files on remote file servers that are accessed over a standard TCP/IP network. The NFS client built into the ESXi system uses NFS version 3 to communicate with NAS/NFS servers. For network connectivity, the host requires a standard network adapter.

Mounting

To use NFS as a shared repository, you create a directory on the NFS server and then mount the directory as a datastore on all hosts. If you use the datastore for ISO images, you can connect the virtual machineʹs CD‐ROM device to an ISO file on the datastore and install a guest operating system from the ISO file.

ESXCLI Command Set

NFS

Troubleshooting

  • Check the MTU size configuration on the port group which is designated as the NFS VMkernel port group. If it is set to anything other than 1500 or 9000, test the connectivity using the vmkping command

NFS3

  • See table below for command explanation

NFS4

  • Verify connectivity to the NFS server and ensure that it is accessible through the firewalls
  • Use netcat (nc) to see if you can reach the NFS server nfsd TCP/UDP port (default 2049) on the storage array from the host:

NFS2

  • Verify that the ESX host can vmkping the NFS server
  • Verify that the virtual switch being used for storage is configured correctly
  • Ensure that there are enough available ports on the virtual switch.
  • Verify that the storage array is listed in the Hardware Compatibility Guide
  • Verify that the physical hardware functions correctly.
  • If this is a Windows server, verify that it is correctly configured for NFS.
  • Verify that the permissions of the NFS server have not been set to read-only for this ESX host.
  • Verify that the NFS share was not mounted with the read-only box selected.
  • Ensure the access on the NFS server is set to Anonymous user, Root Access (no_root_squash), and Read/Write
  • If you cannot connect to an NFS Share there may be a misconfiguration on the Switch port. In this case, try using a different vmnic (or move NICs to Unused/Standby in the NIC teaming tab of the vSwitch or Portgroup properties).
  • The name of the NAS server is not resolved from the host side or vice versa. In this case, ensure that the DNS server and host-side entries are set properly.

Apply VMware storage Best Practices

January 10, 2013 Objective 1 Storage No comments

best-practice

Datastore supported features

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VMware supported storage related functionality

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Storage Best Practices

  • Always use the Vendors recommendations whether it be EMC, NetApp or HP etc
  • Document all configurations
  • In a well-planned virtual infrastructure implementation, a descriptive naming convention aids in identification and mapping through the multiple layers of virtualization from storage to the virtual machines. A simple and efficient naming convention also facilitates configuration of replication and disaster recovery processes.
  • Make sure your SAN fabric is redundant (Multi Path I/O)
  • Separate networks for storage array management and storage I/O. This concept applies to all storage protocols but is very pertinent to Ethernet-based deployments (NFS, iSCSI, FCoE). The separation can be physical (subnets) or logical (VLANs), but must exist.
  • If leveraging an IP-based storage protocol I/O (NFS or iSCSI), you might require more than a single IP address for the storage target. The determination is based on the capabilities of your networking hardware.
  • With IP-based storage protocols (NFS and iSCSI) you channel multiple Ethernet ports together. NetApp refers to this function as a VIF. It is recommended that you create LACP VIFs over multimode VIFs whenever possible.
  • Use CAT 6 cabling rather than CAT 5
  • Enable Flow-Control (should be set to receive on switches and
    transmit on iSCSI targets)
  • Enable spanning tree protocol with either RSTP or portfast
    enabled. Spanning Tree Protocol (STP) is a network protocol that makes sure of a loop-free topology for any bridged LAN
  • Configure jumbo frames end-to-end. 9000 rather than 1500 MTU
  • Ensure Ethernet switches have the proper amount of port
    buffers and other internals to support iSCSI and NFS traffic
    optimally
  • Use Link Aggregation for NFS
  • Maximum of 2 TCP sessions per Datastore for NFS (1 Control Session and 1 Data Session)
  • Ensure that each HBA is zoned correctly to both SPs if using FC
  • Create RAID LUNs according to the Applications vendors recommendation
  • Use Tiered storage to separate High Performance VMs from Lower performing VMs
  • Choose Virtual Disk formats as required. Eager Zeroed, Thick and Thin etc
  • Choose RDMs or VMFS formatted Datastores dependent on supportability and Aplication vendor and virtualisation vendor recommendation
  • Utilise VAAI (vStorage APIs for Array Integration) Supported by vSphere 5
  • No more than 15 VMs per Datastore
  • Extents are not generally recommended
  • Use De-duplication if you have the option. This will manage storage and maintain one copy of a file on the system
  • Choose the fastest storage ethernet or FC adaptor (Dependent on cost/budget etc)
  • Enable Storage I/O Control
  • VMware highly recommend that customers implement “single-initiator, multiple storage target” zones. This design offers an ideal balance of simplicity and availability with FC and FCoE deployments.
  • Whenever possible, it is recommended that you configure storage networks as a single network that does not route. This model helps to make sure of performance and provides a layer of data security.
  • Each VM creates a swap or pagefile that is typically 1.5 to 2 times the size of the amount of memory configured for each VM. Because this data is transient in nature, we can save a fair amount of storage and/or bandwidth capacity by removing this data from the datastore, which contains the production data. In order to accomplish this design, the VM’s swap or pagefile must be relocated to a second virtual disk stored in a separate datastore
  • It is the recommendation of NetApp, VMware, other storage vendors, and VMware partners that the partitions of VMs and the partitions of VMFS datastores are to be aligned to the blocks of the underlying storage array. You can find more information around VMFS and GOS file system alignment in the following documents from various vendors
  • Failure to align the file systems results in a significant increase in storage array I/O in order to meet the I/O requirements of the hosted VMs