It seems Virtual SAN is on fire… I’ve been getting emails about VSAN configurations on a daily basis from partners, VMware field and customers. More and more customers seem to be looking at deploying Virtual SAN with a high number of disks and this week I ran in to something that I wanted to share with you. I thought it was common knowledge, but I guess I was wrong. If you are planning to have more than 8 disks / devices in your Virtual SAN host then it is good to know that you will either need a second disk controller (Check the HCL!) or use a SAS Expander! This design / sizing principle is listed in the VSAN Ready Node PDF, and should also make its way to the Design / Sizing Guide soon. The following is mentioned in the VSAN Ready Node PDF:
No more than 8 disks (SSD + HDD) supported behind a single controller. In case you need to add more than 8 disks, please add an additional controller.
I met up with the product manager for the compatibility guide and asked him which SAS Expanders are supported, he mentioned that support is done per platform and that the following vendors and platforms have just been update. Note that the HCL will still need to be updated for these:
- Dell SAS Expanders 5.5 and 6.0 hybrid. Supported on a specific configuration: H730 on 730d platform with 24 drives.
- Lenovo SAS Expanders 5.5. Supported on a specific configuration: Lenovo 720ix, RD650 platform with 12 drives.
We also are working on support for HP and Cisco (and others over time), and you can also expect an update on those soon. For now, keep in mind that when designing / planning for Virtual SAN the number of virtual disks may mean you need to change the configuration of your host.