Hi everyone, I need to install a vSAN on a PowerEdge R740XD equipped with 1 SSD for caching and 2 HDD for capacity. Now I am considering to use a USB to boot ESX or to add a new HDD. My question is: if I use an entire HDD, can I share the same controller with the other capacity disk? Is there any best practices? HDD or USB?
"Now I am considering to use a USB to boot ESX or to add a new HDD."
By USB, do you mean SD-card via USB-controller?
If so then this is (generally) a cost-effective option but shouldn't be also used for persistent logging as it will burn out relatively quickly.
"My question is: if I use an entire HDD, can I share the same controller with the other capacity disk?"
This depends - this is supported if it is in the same mode as the vSAN devices (e.g. passthrough) and the drive is not used for any VMs (e.g. only logging/dump etc.) then this is supported except on H730 where you have to remove every trace of VMFS after install is complete (and no logging in this case). However I would advise something inside the box e.g. SD-card/SATADOM as it can depend on the controller and there are some new provisions in 6.7 which may change what is supported.
Some useful articles relevant to your question:
We are using a dual SD card (with RAID1) in our Dell R630 servers.
In the newer Dell Rx40er Servers this feature is called BOSS (Boot optimized storage solution) and consists of two M.2 SATA SSDs (RAID1, too).
Even better method than running your ESXi installation from USB or harddrives.
Please check the below link addressing the same concern:
Dell offer Dual SD Card (16-64GB in size) or BOSS which mean 2x 120GB M.2 SSD as RAID 1. Both are supportet under vSphere and the DUAL SD is in use for years in our Hosts. We now have odered a couple of R740 with BOSS.
here my summary:
Concerning the costs is DUAL SD the cheapest, followed by BOSS...
Hm ok. We've ordered them in this configuration with VMware on it direct at Dell.
Until now no problems with VMware support cases on this machines ...