This article will answer the following questions:
- What limitations are there in the different ESX or VirtualCenter (VC) versions for storage information?
- Why is IOPS or Latency storage information missing from some VMs in my environment?
- Why can't I see NFS statistics for my ESX 4.0 hosted VMs?
- Why do my VMs hosted on NFS return identical statistics on ESX 4.1?
VMWare progressively introduced support for storage statistics as they progressed from ESX 4.0 through to ESX 5.0+.
Earlier versions of ESX did not support the full range of statistics, and so VirtualCenter (and, VMTurbo, which uses the VC collection mechanism via the API) cannot report on those that are missing.
In addition, there is a known issue with ESX4.1, where VMs residing on the same NFS datastore incorrectly report identical IOPS and Latency values. This can be observed within the VirtualCenter views, independently of VMTurbo too. Note that this only affects VMs on the same NFS datastore. If you are affected by this, VMTurbo recommends contacting VMware support to add your name to the list of customers reporting this problem.*
The following table summarises the above information, and provides further detail:
To help interpret the above table, remember that there are NFS and other storage types, and, for each of those we have StorageAmount (capacity consumption), StorageProvisioned (Amount of storage allocated/provisioned for the VMs), Latency and IOPS.
*If you are affected by the VMware 4.1 ESX NFS performance bug, as a workaround to this VMWare data problem (which only affects NFS datastores, in ESX 4.1), VMTurbo also recommends that you increase the "IOPS Capacity" values for the affected datastores to a very large number, this will then take the IOPS out of consideration, and the algorithm will rely instead on Latency (and, the constraint of space) to indicate performance constraints.
Storage Move recommendations will then be made to redistribute the workload and maintain the optimal operating zone.
You can configure the IOPS Capacity using the "Policy" tab in VMTurbo, selecting "Storage" and choosing the affected cluster, as shown below: