Continuing on my set of posts related to Virtual SAN (VSAN) interoperability, let’s take a look at how vCenter Operations Manager (vC Ops for short) integrates with Virtual SAN. vC Ops version 5.8, which was released in December 2013, recognizes the VSAN datastore and can report various characteristics, as you might expect. Although vC Ops 5.8 was released around 3 months before VSAN GA’ed, this release works with ESXi 5.5U1 and vCenter 5.5U1, the vSphere release which introduced VSAN. However, this release of vC Ops does not present all the ‘storage’ metrics for VSAN like it does for datastores based on other storage types. But, having said that, there are still a number of useful vC Ops views and metrics that you might find useful which this post will cover.
I’ve been having lots of fun lately in my new role in Integration Engineering. It is also good to have someone local once again to bounce ideas off. Right now, that person is Paudie O’Riordan (although sometimes I bet he wishes I was in a different timezone ). One of the things we are currently looking at is a VSAN implementation using Fusion-io ioDrive2 cards (which our friends over at Fusion-io kindly lent us). The purpose of this post is to show the steps involved in configuring these cards on ESXi and adding them as nodes to a VSAN cluster. However, even though I am posting about it, Paudie did most of the work, so please consider following him on twitter as he’s got a lot of good vSphere/Storage knowledge to share.
I was going to make this part 11 of my vSphere 5.5 Storage Enhancements series, but I thought that since this is such a major enhancement to storage in vSphere 5.5, I’d put a little more focus on it. vFRC, short for vSphere Flash Read Cache, is a mechanism whereby the read operations of your virtual machine are accelerated by using an SSD or a PCIe flash device to cache the disk blocks of the application running in the Guest OS of your virtual machine. Now, rather than going to magnetic disk to read a block of data, the data can be retrieved from a flash cache layer to improve performance and lower latency. This is commonly known as write-through cache, as opposed to write-back cache, where the write operation is acknowledged when the block of data enters the cache layer.
This is an interesting announcement for those of you following emerging storage technologies. We’ve been talking about flash technologies for some time now, but for the most part flash has been either an SSD or PCIe device. Well, we now have another format – DIMM-based flash storage device. And VMware now supports it.
For those of you participating in the VMware Virtual SAN (VSAN) beta, this is a reminder that there is a VSAN Design & Sizing Guide available on the community forum. It is part of the Virtual SAN (VSAN) Proof of Concept (POC) Kit, and can be found by clicking this link here. The guide has recently been updated to include some Host Memory Requirements as we got this query from a number of customers participating in the beta. The actual host memory requirement directly related to the number of physical disks in the host and the number of disk groups configured on the host. If you want to know more about disk groups, have a read of an article that I wrote about disk groups on the vSphere storage blog. Note that these are minimum host memory requirements but VSAN will not actually consume all of this memory.
I had a customer reach out to me recently to discuss VMware’s Storage I/O Control behavior and Adaptive Queuing behavior and how it works with QLogic’s Execution Throttle feature. To be honest, I didn’t have a good understanding of the Execution Throttle mechanism from QLogic so I did a little research to see if this feature inter-operates with VMware’s own I/O congestion management features.
This is a topic which has been discussed time and time again. It relates to an advanced storage parameter called Disk.SchedNumReqOutstanding, or DSNRO for short. There are a number of postings out there on the topic, without me getting into the details once again. If you wish to learn more about what this parameter does for you, I recommend reading this post on DSNRO from my good pal Duncan Epping. Suffice to say that this parameter is related to virtual machine I/O fairness. In this post, I’ll talk about changes to DSNRO in vSphere 5.5.