vSAN Erasure Coding Failure Handling

I had a very interesting question recently about how vSAN handles a failure in an object that is running with an erasure coding configuration. In the case of vSAN this is either a RAID-5 or a RAID-6. On vSAN, a RAID-5 is implemented with 3 data segments and 1 parity segment (3+1), with parity striped across all four components. RAID-6 is implemented as 4 data segments and 2 parity segments (4+2), again with the parity striped across all of the six components. Now, on vSAN, RAID-5 requires 4 physical ESXi hosts for implementation, with each host backing one set of…

Sizing for large VMDKs on vSAN

I’ve recently been involved in some design and sizing for very large VMDKs on vSAN. There are a couple of things to keep in mind when doing this, not just the overhead when deciding to go with RAID1, RAID5 or RAID6, but also what this means for component counts. In the following post, I have done a few tests with some rather large RAID-5 and RAID-6 VMDKs, just to show you how we deal with it in vSAN. If you are involved in designing and sizing vSANs for large virtual machines, you might find this interesting.

VSAN 6.2 Part 2 – RAID-5 and RAID-6 configurations

Those of you familiar with VSAN will be aware that when it comes to virtual machine deployments, historically, objects on the VSAN datastore were deployed either as a RAID-0 (stripe) or a RAID-1 (mirror) or a combination of both. From a capacity perspective, this was quite an overhead. For instance, if I wanted my VM to tolerate 1 failure, I need two copies of the data. If I wanted my VM to tolerate 2 failures, I needed three copies of the data and if I wanted my VM to tolerate the maximum number of failures, which is 3, then I…

An overview of the new Virtual SAN 6.2 features

If you were wondering why my blogging has dropped off in recent months, wonder no more. I’ve been fully immersed in the next release of VSAN. Today VMware has just announced the launch of VSAN 6.2, the next version of VMware’s Virtual SAN product. It is almost 2.5 years since we launched the VSAN beta at VMworld 2013, and almost 2 years to the day since we officially GA’ed our first release of VSAN way back in March 2014. A lot has happened since then, with 3 distinct releases in that 2 year period (6.0, 6.1 and now 6.2). For…