3 ms·

So you are using SMR drives. Wow, good luck with that. All the flash front-end caching in the world won't improve the miserable performance of those drives. I g

by scurvy 11y ago

So you are using SMR drives. Wow, good luck with that. All the flash front-end caching in the world won't improve the miserable performance of those drives. I guess that's the only way to justify moving out of AWS? I'd really like to see some usage stats on your SMR clusters because so far the universal verdict is that they're terrible for anything other than WORM.

olavgg 11y ago
SMR drives may have poor write performance, but still good enough). Read performance is good. Anyway I believe the network is the bottleneck anyway, not the drives.
- scurvy 11y ago
  That fits the WORM profile that I suggested. During normal operation, the disk IOPS is the bottleneck. The network only becomes the bottleneck during repair/failure states. Even scrubbing falls under disk IOPS and not network. At least that's what I've found in EC clusters. Replicated clusters might be different.
jamwt 11y ago
Host Managed (or Host Aware) SMR disks are fine. You need to do your own zone management using ZAC/ZBC, and throw out your filesystem. The disks all have a conventional section near LBA 0 for metadata management (e.g. indices). Usual tradeoff--more work in software, but far less $.
- codemac 11y ago
  Ah good, now we're talking specifics. Does REPORT ZONES not point to this conventional section always? I cannot wait for a FORMAT ALL ZONES or something command to control the number/amount of conventional sections at the sacrifice of capacity, though it looks like it's not coming. The power guarantees in the zbc spec (as of r03) seem to not be held by some drives. Writing less than a full zone seems to be a bad idea.
  - jamwt 11y ago
    > Ah good, now we're talking specifics. Well, specifics within a hypothetical. Hypotheticals are always game to to discuss. :-) > Does REPORT ZONES not point to this conventional section always? Yep, REPORT ZONES includes the conventional zone. > I cannot wait for a FORMAT ALL ZONES I agree that would be nice, but there are no indications that anyone but the vendor will control conventional vs. sequential layout, sequential sizes, or maximum # of explicitly open zones, anytime soon (absent asking for special favors for a large batch order).

by scurvy 11y ago

olavgg 11y ago

SMR drives may have poor write performance, but still good enough). Read performance is good. Anyway I believe the network is the bottleneck anyway, not the drives.

scurvy 11y ago
That fits the WORM profile that I suggested. During normal operation, the disk IOPS is the bottleneck. The network only becomes the bottleneck during repair/failure states. Even scrubbing falls under disk IOPS and not network. At least that's what I've found in EC clusters. Replicated clusters might be different.

jamwt 11y ago

Host Managed (or Host Aware) SMR disks are fine. You need to do your own zone management using ZAC/ZBC, and throw out your filesystem. The disks all have a conventional section near LBA 0 for metadata management (e.g. indices). Usual tradeoff--more work in software, but far less $.

codemac 11y ago
Ah good, now we're talking specifics. Does REPORT ZONES not point to this conventional section always? I cannot wait for a FORMAT ALL ZONES or something command to control the number/amount of conventional sections at the sacrifice of capacity, though it looks like it's not coming. The power guarantees in the zbc spec (as of r03) seem to not be held by some drives. Writing less than a full zone seems to be a bad idea.
- jamwt 11y ago
  > Ah good, now we're talking specifics. Well, specifics within a hypothetical. Hypotheticals are always game to to discuss. :-) > Does REPORT ZONES not point to this conventional section always? Yep, REPORT ZONES includes the conventional zone. > I cannot wait for a FORMAT ALL ZONES I agree that would be nice, but there are no indications that anyone but the vendor will control conventional vs. sequential layout, sequential sizes, or maximum # of explicitly open zones, anytime soon (absent asking for special favors for a large batch order).