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…
Now that VSAN 6.2 is officially launched, it is time to start discussing some of the new features that we have introduced into our latest version of Virtual SAN. Possibly one of the most eagerly anticipated feature is the introduction of deduplication and compression, two space efficiency techniques that will reduce the overall storage consumption of the applications running in virtual machines on Virtual SAN. Of course, this also lowers the economics of running an all-flash VSAN, and opens up all-flash VSAN to multiple use cases.
I had a query recently from a partner who was deploying VMware Horizon View 6.1 on top of an all-flash VSAN 6.0. They had done all the due diligence with configuring the AF-VSAN appropriately, marking certain flash devices as capacity devices, and so on. The configuration looked something like this: The they went ahead and deployed Horizon View 6.1, which they had done many times before on hybrid configurations. They were able to successfully deploy full clone pools on the AF-VSAN, but hit a strange issue when deploying linked clone pools (floating/dedicated). The clone virtual machine operation would fail with…
With the release of VSAN 6.0, and the new all-flash configuration (AF-VSAN), I have received a number of queries around our 10% cache recommendation. The main query is, since AF-VSAN no longer requires a read cache, can we get away with a smaller write cache/buffer size? Before getting into the cache sizing, it is probably worth beginning this post with an explanation about the caching algorithm changes between version 5.5 and 6.0. In VSAN 5.5, which came as a hybrid configuration only with a mixture of flash and spinning disk, cache behaved as both a write buffer (30%) and read…
In Virtual SAN version 6.0, VMware introduced support for an all-flash VSAN. In other words, both the caching layer and the capacity layer could be made up of flash-based devices such as SSDs. However, the mechanism for marking some flash devices as being designated for the capacity layer, while leaving other flash devices as designated for the caching layer, is not at all intuitive at first glance. For that reason, I’ve included some steps here on how to do it.