Re:Demystifying OpenZFS 2.0
by magicalhippo on Thursday November 18, 2021 @05:46PM
(#29271581)
Fair enough, I should have just called it cache.
The point remains though. The ZIL is not meant to be a cache. The SLOG (which is a "ZIL on a separate device") could be viewed as a cache, but it's a cache for the ZIL. Thus being a cache for writes is incidental, not the primary purpose.
Certainly, if your workload aligns with those conditions, then you will experience a performance boost. For other workloads it it won't help and for certain workloads it can even be detrimental[1].
The point remains though. The ZIL is not meant to be a cache. The SLOG (which is a "ZIL on a separate device") could be viewed as a cache, but it's a cache for the ZIL. Thus being a cache for writes is incidental, not the primary purpose.
Certainly, if your workload aligns with those conditions, then you will experience a performance boost. For other workloads it it won't help and for certain workloads it can even be detrimental[1].
[1]: https://www.reddit.com/r/zfs/comments/m6ydfv/performance_eff...