Redundancy in your storage system which is
the main selling point of ZFS. I want all my storage to survive the failure of at least one component. So my VM storage is 2 NVMe disks in a mirror configuration. But then I do not export that to ESXi but run the VMs on top of that pool in TrueNAS.
But yes, that's my main point. Never ever have anything on just a single drive. Drives fail.
So in your case my line of thinking is:
- It's still just a single drive.
- Sharing over iSCSI wastes half of the capacity.
- At lower performance because of the iSCSI and network overhead (I don't have an idea how much precisely for this one).
- So just put the NVMe drive in ESXi and do regular snapshots and backups with GhettoVCB.
- Essentially: iSCSI in this case is a waste of ressources/money.
Now if you build a hundred terabyte pool for an enterprise VMware cluster, that's a different story.
There were some proper figures for the performance degradation when you fill a pool that serves as an iSCSI VM backend. And yes, the figures were dramatic somewhere between the 40% and the 60% mark. For a home setup that might still be ok above 60% ... noone can tell unless you measure.
Does anyone of the other regulars have the link to those benchmarks handy?
So my main motivation is "don't lose data" (obviously) but also "if possible keep availability as high as possible in a home setup". I run private yet productive services on these systems and I don't want my family Nextcloud nor my parent/teacher assoc wiki to be offline because of a single disk failure while I am on vacation.
So (ever had a look at my signature?)
- all my systems have IPMI
- I have VPN access to my home network from anywhere
- main NAS:
- mirrored boot pool - two Transcend 32 G SATA SSDs
- mirrored VM pool: two Samsung NVMe SSDs
- storage pool: RAIDZ2 spinning disks
- snapshots and replication of the VMs from the SSD pool to the storage pool (RAIDZ2 > mirror in terms of redundancy)
- snapshots and replication of the VMs and everything else on the storage pool to a second system at my office
Now ... what are
your main concerns and which are the applications you absolutely cannot do without?