Taking snapshots with vSAN with failures in the cluster

I was discussing the following situation with some of our field staff today. We are aware that snapshots inherit the same policies as the base VMDK, so if I deployed a VM as a RAID-6, RAID-5, or a RAID-1, snapshots inherit the same configuration. However if I have a host failure in a 6-node vSAN running RAID-6 VMs, or a failure in a 4-node vSAN running RAID-5, or a 3-node vSAN running RAID-1, and I try to take a snapshot, then vSAN does not allow me to take the snapshot as there are not enough hosts in the cluster to…

ATS Miscompare revisited in vSphere 6.5

Does anyone remember the ATS Miscompare issue? This blog post from 2 years ago might jog your memory. It is basically an issue that arose when we began using ATS, the VAAI Atomic Test and Set primitive, for maintaining the ‘liveness’ of a heartbeat in vSphere 5.5U2.  After making this change, a number of customers started to see “ATS Miscompare detected between test and set HB images” messages after upgrading to vSphere 5.5U2 or later. The HB reference in the message is shorthand for heartbeat. In previous releases, we did not use ATS for maintaining the ‘liveness’ of a heartbeat.…

A closer look at Portworx

Last month I had the opportunity to attend DockerCon17. One of the break-out sessions that I attended was from a company called Portworx. Portworx provide a solution for stateful docker container storage, which is what caught my interest. There are lots of companies who have already created docker volume plugins for their existing storage solutions, including VMware. However Portworx seem to be approaching this a bit differently, and are providing a layer of abstraction from the underlying host storage. So you might be using cloud (e.g. EBS from AWS), or SAN or NAS or indeed you might only have local…

A closer look at Cohesity 4.0

Last week, I had a chance to catch up with my pal, Rawlinson Rivera. Rawlinson and I worked closely on a lot of storage related stuff at VMware, but he has since moved on to pastures new, and is currently the CTO for the Global Field over at Cohesity. I’ve written about Cohesity a number of times on this blog. I think the first time I wrote about them was during VMworld 2015, just before the 1.0 product launched, and they were still pitching the idea of secondary storage and how they would take care of things like snaps, clones,…

Debunking some behavior “myths” in 3 node vSAN cluster

I recently noticed a blog post describing some very strange behaviors in 2-node and 3-node vSAN clusters. I was especially concerned to read that when they introduced a failure and then fixed that failure, they did not experience any auto-recovery. I have reached out to the authors of the post, just to check out some things such as version of vSAN, type of failure, etc. Unfortunately I haven’t had a response as yet, but I did feel compelled to put the record straight. In the following post, I am going to introduce a variety of operations and failures in my…

vSphere 6.0 Update 3 – Important Update for vSAN

ESXi 6.0 Update 3 is now available. This update is significant for vSAN customers as there are a number of performance related issues addressed. The KB article detailing vSAN performance improvements can be found here, and the ESXi 6.0 U3 release notes can be found here. I wouldn’t necessarily write a blog post to highlight a KB or update release, but I think the improvements that have been made to vSAN performance in this update are very significant. Improvements include enhancements to the way that we do logging. In vSAN, every I/O operation is logged before being processed. We have…

vSphere 6.5 Core Storage White Paper Now Available

I’m delighted to announce the availability of a new vSphere 6.5 core storage white paper. The paper covers new features such as VMFS-6 enhancements, policy driven Storage I/O Control, policy driven VM Encryption, NFS and iSCSI improvements and of course new limit increases in vSphere 6.5. There are too many VMware folks to thank for putting this paper together, but you’ll find them all listed in the acknowledgements section. I do want to mention one person however; a very special thanks to Cody Hosterman of Pure Storage who spent a lot of time testing many of these new features, and…