I posted the Site Maintenance demo, so I figured I would also do a post for the Site Takeover feature. I described those features in a few posts. So make sure to read that if you don’t know what it is about. If you already know, but haven’t seen a demo yet, here you go:
VMware
vSAN 9.0 Site Maintenance Mode demo!
I had a few questions about this, so I figured I would record a quick demo showing Site Maintenance. In the demo, I have a stretched cluster configured in vSAN 9.0, and I am going to place the Preferred Site into maintenance mode. First a pre-check will occur to verify all workloads are replicated between locations, and then the site is placed into maintenance while maintaining data consistency across hosts. Next demo I will record will show the Manual Site Takeover command that was also introduced in 9.0 for OSA, but will be also available soon for ESA.
vSAN Stretched Cluster vs Fault Domains in a “campus” setting?
I got this question internally recently: Should we create a vSAN Stretched Cluster configuration or create a vSAN Fault Domains configuration when we have multiple datacenters within close proximity on our campus? In this case, we are talking about less than 1ms latency RTT between buildings, maybe a few hundred meters at most. I think it is a very valid question, and I guess it kind of depends on what you are looking to get out of the infrastructure. I wrote down the pros and cons, and wanted to share those with the rest of the world as well, as it may be useful for some of you out there. If anyone has additional pros and cons, feel free to share those in the comments!
vSAN Stretched Clusters:
- Pro: You can replicate across fault domains AND protect additionally within a fault domain with R1/R5/R6 if required.
- Pro: You can decide whether VMs should be stretched across Fault Domains or not, or just protected within a fault domain/site
- Pro: Requires less than 5MS RTT latency, which is easily achievable in this scenario
- Con/pro: you probably also need to think about DRS/HA groups (VM-to-Host)
- Con: From an operational perspective, it also introduces a witness host, and sites, which may complicate things, and at the various least requires a bit more thinking
- Con: Witness needs to be hosted somewhere
- Con: Limited to 3 Fault Domains (2x data + 1x witness)
- Con: Limited to 20+20+1 configuration
vSAN Fault Domains:
- Pro: No real considerations around VM-to-host rules usually, although you can still use it to ensure certain VMs are spread across buildings
- Pro: No Witness Appliance to manage, update or upgrade. No overhead of running a witness somewhere
- Pro: No design considerations around “dedicated” witness sites and “data site”, each site has the same function
- Pro: Can also be used with more than 3 Fault Domains or Datacenters, so could even be 6 Fault Domains, for instance
- Pro: Theoretically can go up to 64 hosts
- Con: No ability to protect additionally within a fault domain
- Con: No ability to specify that you don’t want to replicate VMs across Fault Domains
- Con/Pro: Requires sub-1ms RTT latency at all times, which is low, but will be achievable in a campus cluster, usually
#101 – Discussing VCF 9.0 and Private AI Foundation with NVIDIA enhancements with Frank Denneman!
It was time to get Frank Denneman back on the show to discuss the enhancements introduced in VCF 9 and Private AI Foundation with NVIDIA. Frank goes over all new functionality and all the enhancements like Agent Builder etc. Frank also mentioned various must-attend sessions at Explore, register now, as these will fill up fast:
- Chris Wolf, keynote and breakout
- Shawn Kelly and Justin Murray: Accelerating AI Workloads
- Frank’s AI/ML sessions!
You can listen to the episode on Apple Podcasts, Spotify, or anywhere else you find your podcasts! Of course, you can also simply use the embedded player below.
Does vSAN support a Franken cluster configuration?
It is funny that this has come up a few times now, actually for the third time in a month. I had a question if you can mix AMD and Intel hosts in the same cluster. Although nothing stops you from doing this, and vSAN supports this configuration, you need to remember that you cannot live migrate (vMotion) between those hosts, which means that if you have DRS enabled you are seriously crippling the cluster as it makes balance resource much more complex.
You are creating a Franken cluster when mixing AMD and Intel. You may ask yourself, why would anyone want to do this in the first place? Well, you could do this for migration purposes for instance. If you use vSAN iSCSI Services for instance, this could be a way to migrate those iSCSI LUNs from old hosts to new host. How? Well, simply add the new hosts to the cluster, place the old hosts into maintenance, and make sure to migrate storage. Do note, all the VMs (or containers) will have to be powered off, and powered on again manually on the new hosts, as a result of moving from Intel to AMD (or the other way around).
If you do end up doing this for migration purposes, please ensure it is for the shortest time possible. Please avoid running with a Franken cluster for multiple days, weeks, or, god forbid, months. Nothing good will come out of it, and your VMs may become little monsters!
