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Posts in Virtualization
Using the vSphere flash read cache feature to speed up sequential reads
Duncan Epping gave a great overview of vSphere's flash read cache feature and I wanted to take it for a ride. This feature reminds me of the ZFS level-2 ARC which allows SSD drives to be used as read and write caches. The vSphere vcache only provides read caching but that is still super useful for read-intensive workloads. To see how it performed I broke out my trusty old sequential read script to get a baseline: Not too shabby for my old rusty NFS datastore…
$ read more →The power of locality in VMware vSphere environments
I was doing some network throughput testing last weekend and wanted to see how much locality played into virtual machine deployments. The VMware virtual vmxnet3 network adapter is capable of 10Gb/s+ speeds and was designed to be extremely performant. To see what kind of throughput I could get over a 1Gb/s link I fired up my old trusty friend iperf and streamed 6GB of data between VMs located on different ESXI hosts: This was about what I expected given the theoretical maximums of 1Gb/s copper l inks. To see how things performed when both VMs were co-located I vmotioned one of the servers and re-ran the test: The vmxnet3 adapter is not just capable of pushing 10Gb/s it is capable of pushing data as fast as the motherboard and chip set allow…
$ read more →Troubleshooting vSphere NSX manager issues
This week I installed VMWare NSX and created a new NSX manager instance. After deploying the OVF and prepping my cluster members I went to create the three recommended controller nodes. This resulted in a "Failed to power on VM NSX Controller" error which didn't make sense. The package was installed correctly, the configuration parameters were correct and I double and tripled checked that the controllers could communicate with my NSX manager…
$ read more →Scalable storage for QEMU/KVM
While reading up on various scalable file systems I came across the sheepdog project. For those new to sheepdog, their website describes it as: "Sheepdog is a distributed storage system for QEMU/KVM. It provides highly available block level storage volumes that can be attached to QEMU/KVM virtual machines. Sheepdog scales to several hundreds nodes, and supports advanced volume management features such as snapshot, cloning, and thin provisioning." This looks really cool, and I'm hoping to play around with it this weekend…
$ read more →Centos 6 Linux VMs running inside vSphere 4.1 appear to dynamically discover new LUNs
I came across an interesting discovery yesterday while working on a CentOS 6 gluster node. The node was virtualized inside vSphere 4.1 and needed some additional storage added to it. I went into the VI client and added a new disk while the server was running, expecting to have to reboot or rescan the storage devices in the server. Well, I was pleasantly surprised when the following messages popped up on the console: Nice, it looks like the device was added to the system dynamically…
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