vSAN The Case for Single Socket
I had previously discussed in a rather click bait title of an article how falling storage prices were making vSAN cheaper. As the economics of flash + perpetual socket licensing made the cost per GB for vSAN (and cost per VM) go down over time. It’s 2019 and I wanted to example what those old hosts that need to be replaced might look like.
- 2 x 8 core processors (Intel Xeon v3)
- 3.6TB to 6TB RAW capacity (3 or 5 x 1.2TB 10K RPM drives) with 400-800GB of SATA/SAS SSD Cache.
- 128 GB RAM.
- 4 host cluster
Now, this host would require two sockets of vSAN and vSphere licensing for a total of 8 sockets.
Now going into 2019, we are ready to replace these nodes and deploy new ReadyNodes.
Moving forward to 2019 a host might look something like this:
- 1 x 16 core processors (Xeon Scalable, or AMD EYPC now as a very viable option).
- 256 GB of RAM
- 32TB of RAW NVMe with 2 x 800GB of NVMe Cache.
- 8 host cluster
Let’s look at a few improved density capabilities:
- Single Socket, because realistically this system should be able to run more than twice the workloads as the older processor.
- Less overhead. The overhead for CPU as a % of the cluster for N+1 capacity planning drops from 25% for a four-host cluster, to a 12.5% for an 8 host cluster.
- AMD EPYC allows for use of all memory channels and PCI lanes so for workloads that will fit within a processor scaling out has some natural efficiency.
- Single socket cuts the licensing count in half for hosts, allowing me to run twice the hosts for the same licensing cost.
- All Flash lets me use Erasure Codes along with Deduplication and compression and the 5-8x more RAW capacity mean I can store a LOT more data. RAID 6 vs FTT=2 mirroring cuts overhead in half.
- Performance Improvements as a result of the all NVMe configuration along with code improvements going from older to newer vSAN IO path code.
A couple other big wins here:
1. Unlike a storage array or appliance I didn’t have to re-buy licensing. Nothing was “thrown away” in this transition. No sales guy came out and scared me with a scary renewal before offering me some insane trade in play to some new platform I’m not familiar with. At no point in the purchase of new hardware did I feel the process should be described as a “Barking Carnival” or a “Goat Rodeo”. I might upgrade some license versions, but the existing value and that delta cost remained the same and no one was trying to force me to make a transaction.
2. I doubled my host count without doubling my licensing or support renewals. Say it with me “I should expect MORE VALUE from my HCI solution as the investment ages, not less!”.
3. I increased my compute capabilities with the same socket count by 4x or more. Inversely if I was a large shop not growing, I might even consolidate my fleet, shift some licenses to cover DR, or other environments to expand on my vSAN success. I can even split up these nodes to do this. A traditional storage frame unfortunately can’t be cut into three pieces and reused at 3 sites.
4. I massively increased by storage performance and capacity footprint. The old hardware may get phased out for a lab, used for DR, or sent to recycling but my vSAN investment carried forward through this growth. No one at VMware “tax’d” me for adding hosts, cores, performance, or capacity to expand my environment.