Administrator Guide
19 Dell FS8600 with VMware vSphere Deployment and Configuration Best practices
7 Datastores Configuration
NFS Datastores in vSphere represent ESX host mounts, each accessing an NFS export over an IP address. Note that an
ESX host creates a single I/O connection to the FS8600 for every individual datastore. Regardless of the teaming or load
sharing method, this connection is given (and limited to) a single physical path to the FS8600, composed of one physical
link from the ESX host to the switch and one from the switch to the FS8600 controller. As described in this section,
creating a minimum number of datastores allows you to fully utilize the paths between ESX hosts and the FS8600,
maximize the aggregated throughput and add an additional level of throughput management across the physical links.
7.1 Determining the Number of Datastores in the Environment
The recommended number of datastores in an environment varies, and depends on several considerations:
1. Number of physical links between the ESX host and the switch: Creating at least one datastore per link ensures
full utilization of the maximum aggregate throughput. Their configuration depends on the load sharing method
in use (See NFS Datastore Traffic Load Sharing14). For subnet-based load sharing, configure at
least one datastore per subnet.
2. Link speed distribution among the ESX host links: Two or more datastores in the same subnet will maintain
their connections over the same physical link; hence their aggregated throughput will be limited by the link
speed. This mode of operation adds an additional level of throughput management that, if leveraged, can also
impact the number of datastores. For example, on an ESX host with a two physical link connection, an
administrator can grant maximum link speed to a single datastore by creating it in the first subnet and all others
in the second.
7.2 Increasing the Maximum Number of NFS Datastores per ESX Host
The parameter that defines the maximum number of NFS mounts (datastores) on each ESX host is set to 8 by default. In
environments where more than 8 NFS datastores are needed, this parameter can be increased (up to 256). When
increasing this number, VMware recommends increasing the TCP/IP heap size, which is the amount of memory in
megabytes allocated up front by the VMkernel to TCP/IP as heap.
The maximum number of NFS mounts an ESX host can have is determined by the NFS.MaxVolumes parameter.