VSAN Part 16 – Reclaiming disks for other uses

A number of customers have raised this question. How do you reclaim disks which were once used by VSAN but you now wish to use these disks for other purposes? Well, first off, if you are using some of the later builds of VSAN and you place the host into maintenance mode and remove the disk group from the host, this will automatically remove the partitions from the disks and you are good to go with reusing these disks for some other purpose. However, if you do something such as reinstall ESXi on the host but do not go through…

A closer look at vSphere Flash Read Cache – vFRC

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…

A closer look at Fusion-io ioControl 3.0

Last week I had the opportunity to catch up with Mike Koponen and Dean Steadman of Fusion-io. I had met with Mike and Dean at VMworld 2013, and spoke to them about the Fusion-io acquisition of NexGen storage earlier last year, and what plans Fusion-io had for this acquisition. Well, the result is ioControl Hybrid Storage, and we discussed some of the architecture of ioControl as well as a number of vSphere integration points.

VSAN Part 15 – Multicast Requirement for networking – Misconfiguration detected

This is an issue which has caught a number of customers out during the Virtual SAN beta, so will probably catch some folks out when the product goes live too. One of the requirements for Virtual SAN (VSAN) is to allow multicast traffic on the VSAN network between the ESXi host participating in the VSAN Cluster. However, as per our engineering lead on VSAN, multicast is only used for relatively infrequent metadata operations. For example, object creation, change in object status after a failure and publication of statistics such as a significant change of free disk space (the publication of…

QLogic – Execution Throttle Feature Concerns

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.

vSphere 5.5 Storage Enhancements Part 8 – DSNRO Changes

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.