Hey
I've created a zpool on an external drive with gzip-9 compression and dedup enabled because I'm trying to sort out about a decade worth of backups-with-backups-in-em-that-got-backups-in-em-and-there-was-something-i-added-but-i-cant-remember-what. So, basically multi-terabytes of data with lots of duplication, so I thought, "a 2TB ZFS with dedup oughta do!" And I'm pretty sure it will
Thing is, it's really really slow when writing. It's on a 3.5" USB3 external drive. Some Lacie thing with triple-digit-MB/s performance when just using something standard like HFS+. I first started copying a 250GB set of data to the empty pool using my MacBook Air 2015 with an i7 and 8GB of RAM. After a couple of hours, it estimated 9 more days to complete the copy, so I thought I might try my 2017 MBP with 16 GB of RAM instead. Here, it completed in less than two days. Still awfully slow, though :/
I'm wondering if there's something I need to tweak to get better write performance. 16 GB of RAM is *plenty* for a 2TB dedupped pool, and considering the performance increase from going from my Air to my MBP with twice the RAM, I'm thinking it might very well be memory related?
But then I'm looking at zpool get all, which says, "ashift 0", and I'm wondering if I either forgot to create it with ashift=12, or if "ashift 0" means "default", which is "12" nowadays, or what? Perhaps this is just me being retarded and now stuck with a pool that is suffering from me having forgotten all that old stuff about transitioning to modern drives some years back?
Any ideas greatly appreciated
Thanks!