I have a very old 2 disk MacZFS mirror (so pool version 8). The only nonstandard thing with this pool is I used the zpool_ashift binary linked in the maczfs wiki to set ashift=12. I also set compression = gzip-9 when I created it.
Anyway, I used maczfs for years until it hit a point where I couldn't upgrade os versions anymore so I switched to O3X. I don't remember when now but it's been a few years (I think around when spotlight support was added?)
Out of general paranoia I have not upgraded the pool. I just moved to sierra last week and 1.6.1 worked without any hitches after the upgrade, even though I forgot to export the pool beforehand. (This freaked me out during the last upgrade when the pool wouldn't show up at first )
Anyway, I'm finally sort of ready to upgrade the pool, primarily to get access to zil/cache SSD drives to help performance (the 4tb drives I have are slow green drives and can be somewhat painful) and a couple other features. If it makes any difference the pool is almost full (in fact I had to struggle to delete some things a couple years ago when it accidentally got filled up and didn't act very nicely...)
I'm wondering if there are best practices for doing the upgrade?
I've thought about just doing it and hoping , or trying something like removing one of the mirror drives and doing the upgrade with a single drive, then if it works OK adding that drive back in (I assume I'll have to wipe it first?) I mainly want to not have to completely rebuild it if the upgrade just "fails." Is there some 'test' upgrade mode where it doesn't upgrade it but does upgrade operations with integrity tests or something?
Are there any tests, etc I should run first?
Has anyone tested upgrading from pool version 8 before (I assume so) or recently (maybe not)?
thanks