A couple of questions (SMR and features compared to ZoL)
Posted: Fri May 10, 2019 6:27 am
Hey
I hope it's okay that I ask two unrelated questions here. The forum is pretty quiet, so...
The first one is the quicker one to answer, I guess. I've been trying to use a mac Mini as a NAS basically, with a bunch of 4TB drives in a RAIDZ-3 configuration. I created the pool on macOS with encryption enabled, but I've had a lot of problems getting stability on macOS, with the pool eventually not even being importable without crashing the Mac unless I import it read-only, so I've now switched back to Linux. That's not my question directly, but I've put Ubuntu Server on an older MacBook Air, and when I tried to import the pool, I couldn't use the -l flag, since to my surprise, encryption wasn't in the stable ZoL 0.7.x branch. I compiled the 0.8.0 RC4 binaries (which was a bit of a hassle, as the instructions provided are for 0.7 and below, and in addition the shared libs needed for the compiled binaries are not where the binaries expect them to be, but so far I'm hacking my way to getting the pool up also, not the question). Sorry. The question is: How has O3X been offering encryption for almost half a year now when the ZoL repo, which I'm assuming is the source of O3X, hasn't pulled it out of beta yet? Have I been unknowingly running beta here, or is there some kind of git cherry-picking going on here WRT features, or something entirely different?
Second question: This is an open one. The drives I'm using are 11 4TB 2.5" USB drives, all SMR (clearly no other way to get 4TB in that small of a space). Firstly, I've read a lot of people online suggesting that the COW nature of ZFS ought to be perfect for SMR drives, but in my experience, this is definitely not the case (at least with O3X). I actually recreated this pool from a previous one that wasn't compatible with macOS (OMG, also not the question, but WTF is the default not to NOT enable any OS-exclusive features when creating a pool? OMG, the pain, the months of pain), and it was completely empty. I've been adding back backups, 2TB at a time, just writes, no reads, and every time the writes quickly dipped in transfer speeds to around 4 MB/s. This all while individual drives tested with dd are capable of about 50 MB/s I/O each — which is pretty lame, too, but seems to be the performance of these sub-par WD SMR drives. But I just don't get how ZFS triggers this behavior. Some kind of sync operations forced often that forces some SMR-related firmware operation? Something else? I'm not trying to bash ZFS here, I'm just looking for some way to get around this issue. Oh, and somewhere in my adventure, I added an SLOG device on an SSD in attempt to alleviate the problem, but to no avail.
I know I have a tendency to be a bit ranty when I write like this, so sorry about that. Hope I'm making sense. Also, thank you so much, anyone involved with bringing this beautiful filesystem to my almost every OS. Lundman, I've noticed while watching YouTube and seeing the ZoL commit logs that you're a natural force here, and I'm really grateful.
Oh, and even if these drives I'm using suck, I just replaced two dying ones at the store where I bought them (Elgiganten). The procedure: "So, you're saying they do what?" "Well, I wrote it here, but basically, I cannot read or write to them, even format them, they're just causing USB hubs to reset and throw I/O errors." "Okay, so you take this piece of paper, go back in the store and pick up two new drives, then show it to the lady at the checkout." Yeah, I like that sort of RMA. 5-minute RMA.
I hope it's okay that I ask two unrelated questions here. The forum is pretty quiet, so...
The first one is the quicker one to answer, I guess. I've been trying to use a mac Mini as a NAS basically, with a bunch of 4TB drives in a RAIDZ-3 configuration. I created the pool on macOS with encryption enabled, but I've had a lot of problems getting stability on macOS, with the pool eventually not even being importable without crashing the Mac unless I import it read-only, so I've now switched back to Linux. That's not my question directly, but I've put Ubuntu Server on an older MacBook Air, and when I tried to import the pool, I couldn't use the -l flag, since to my surprise, encryption wasn't in the stable ZoL 0.7.x branch. I compiled the 0.8.0 RC4 binaries (which was a bit of a hassle, as the instructions provided are for 0.7 and below, and in addition the shared libs needed for the compiled binaries are not where the binaries expect them to be, but so far I'm hacking my way to getting the pool up also, not the question). Sorry. The question is: How has O3X been offering encryption for almost half a year now when the ZoL repo, which I'm assuming is the source of O3X, hasn't pulled it out of beta yet? Have I been unknowingly running beta here, or is there some kind of git cherry-picking going on here WRT features, or something entirely different?
Second question: This is an open one. The drives I'm using are 11 4TB 2.5" USB drives, all SMR (clearly no other way to get 4TB in that small of a space). Firstly, I've read a lot of people online suggesting that the COW nature of ZFS ought to be perfect for SMR drives, but in my experience, this is definitely not the case (at least with O3X). I actually recreated this pool from a previous one that wasn't compatible with macOS (OMG, also not the question, but WTF is the default not to NOT enable any OS-exclusive features when creating a pool? OMG, the pain, the months of pain), and it was completely empty. I've been adding back backups, 2TB at a time, just writes, no reads, and every time the writes quickly dipped in transfer speeds to around 4 MB/s. This all while individual drives tested with dd are capable of about 50 MB/s I/O each — which is pretty lame, too, but seems to be the performance of these sub-par WD SMR drives. But I just don't get how ZFS triggers this behavior. Some kind of sync operations forced often that forces some SMR-related firmware operation? Something else? I'm not trying to bash ZFS here, I'm just looking for some way to get around this issue. Oh, and somewhere in my adventure, I added an SLOG device on an SSD in attempt to alleviate the problem, but to no avail.
I know I have a tendency to be a bit ranty when I write like this, so sorry about that. Hope I'm making sense. Also, thank you so much, anyone involved with bringing this beautiful filesystem to my almost every OS. Lundman, I've noticed while watching YouTube and seeing the ZoL commit logs that you're a natural force here, and I'm really grateful.
Oh, and even if these drives I'm using suck, I just replaced two dying ones at the store where I bought them (Elgiganten). The procedure: "So, you're saying they do what?" "Well, I wrote it here, but basically, I cannot read or write to them, even format them, they're just causing USB hubs to reset and throw I/O errors." "Okay, so you take this piece of paper, go back in the store and pick up two new drives, then show it to the lady at the checkout." Yeah, I like that sort of RMA. 5-minute RMA.