I've been meaning to write some follow-up on that question specifically (block storage on RAIDZ using SSDs)
I'd love to give you a short Yes/No answer but as with so many things ZFS, there really isn't one.
Obviously, SSDs don't have the same random I/O penalty of an HDD when it comes to things like fragmentation or having to "work in sync." You can still be subject to a single drive hitting its garbage collection or TRIM process, and stalling out the vdev, but it's not as cripplingly bad as having to make a quartet of HDD spindles all move their arms together.
What you do still have to deal with is poor space utilization and write amplification. With small recordsizes, you're still having to write the parity information. Assuming your Z1 setup, if you write a record that compresses to 4K or smaller (or starts at 4K to begin with) you'll still be writing (one data + one parity) and using two drive's worth of space. Most VM I/O is 4K and 8K in size; however, with your Z1 being quite narrow you'll probably be able to eke out better utilization.
With SSDs you can also push the "usable storage" up a bit higher, as you don't have the random-seek penalty on reads. You will still have to deal with garbage collection/TRIM and keeping a certain percentage of your pool free. How far you can push it will likely depend more on your SSD's ability to clean its NAND pages, how much overprovisioning you have, and what exactly your tolerance for "good performance" is.
Mirrored SSD will still perform better, but RAIDZ SSD is starting to be the 320kbps MP3 of storage - it's often "good enough."
Edit, some further thoughts:
1. "NVMe SSD" doesn't necessarily mean "good for SLOG" - check the signature link for SLOG benchmarking. Needs to be high-endurance with low latency. Optane is excellent for this, but trying to truly saturate 10Gbps with regular I/O may require exotic solutions eg: NVRAM/NVDIMMs.
2. Hyper-V doesn't seem to understand how to throttle TRIM/UNMAP commands to iSCSI devices. This could cause high latencies under live migrations or deletes. See thread below for a minor discussion with a user who was in a similar scenario.
Hi All, Long time lurker here running the following configuration: Dell R720 with 256GB RAM FreeNAS-11.3-U4.1 Dual controller 8 Gbps link to enclosure containing pool disks I am finding an issue where I migrate virtual machine storage off of the platform and onto another (presented via iSCSI...
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