Pluggable Storage Architecture (PSA) Deep-Dive – Part 2

As I highlighted in the PSA part 1 post, NMP, short for Native Multipath Plugin, is the default Multipath Plugin shipped with ESXi hosts. Once the PSA has associated the NMP with particular paths, it uses a number of sub-plugins to handle load balancing and path fail-over. In this post, I will look at the NMP in more detail. I will pay specific attention to the activity of the Storage Array Type Plugin (SATP) which is responsible for handling path fail-over for a given storage array and also the Path Selection Plugin (PSP), which determines which physical path is used…

Pluggable Storage Architecture (PSA) Deep-Dive – Part 1

In this next series of blog articles, I am going to take a look at VMware’s Pluggable Storage Architecture, more commonly referred to as the PSA. The PSA was first introduced with ESX 4.0 and can be thought of as a set of APIs that allows third-party code to be inserted directly into the storage I/O path. Why would VMware want to allow this? The reason is straight forward. This allows 3rd party software developers (typically storage hardware vendors) to design their own load balancing techniques and fail-over mechanisms for their own storage arrays. It also means that 3rd party…

Heads Up! Nutanix NOS v2.6.4 now available

Nutanix have informed me that they have a new release available – Nutanix OS 2.6.4 (NOS is the new name for the previously named Nutanix Complete Cluster). They are looking for all their customers to proactively move to this new release. Although Nutanix also have NOS 3.0 release on the cards, existing customers will first need to move to version 2.6.4 in order to be in a position to migrate to 3.0. If that is not reason enough, the 2.6.4 release also includes the following new features:

Does Software iSCSI on vSphere support IPsec?

This came up in a conversation today. Does VMware’s Software iSCSI implementation support Internet Protocol Security (IPsec) in vSphere 5.1? Internet Protocol Security (IPsec) secures IP communications coming from and arriving at an ESXi host. Although KB article 1021769 states that IPv6 is compatible with Software iSCSI, it doesn’t state whether or not IPsec is supported with Software iSCSI. To find this information, you have to reach for the vSphere Security Guide. Under the section ‘Securing iSCSI Devices Through Authentication’, it states: ESXi does not support Kerberos, Secure Remote Protocol (SRP), or public-key authentication methods for iSCSI. Additionally, it does not…

Adaptive Queueing vs. Storage I/O Control

This post is to look at two different technologies available in vSphere to manage the queue depth on your ESXi host(s). A queue determines how many outstanding I/Os can be sent to a disk. In the case of vSphere environments, where many hosts can be doing I/O to the same shared disk device, it can be helpful to throttle the LUN queue depth from time to time when congestion arises. In this post, we will compare and contrast Adaptive Queues with Storage I/O Control (SIOC).

QLogic Mt. Rainier Technology Preview

I was fortunate enough yesterday to get an introduction to QLogic’s new Mt. Rainier technology. Although Mt. Rainier allows for different configurations of SSD/Flash to be used, the one that caught my eye was the QLogic QLE10000 Series SSD HBAs. These have not started to ship as yet, but considering that the announcement was last September, one suspects that GA is not far off. As the name suggests, this is a PCIe Flash card, but QLogic have one added advantage – the flash is combined with the Host Bus Adapter, meaning that you get your storage connectivity and cache accelerator…