| freebsd.zfs |
Tuning is often evil and should rarely be done.
First, consider that the default values are set by the people who know the most about the effects of the tuning on the software that they supply. If a better value exists, it should be the default. While alternative values might help a given workload, it could quite possibly degrade some other aspects of performance. Occasionally, catastrophically so.
Over time, tuning recommendations might become stale at best or might lead to performance degradations. Customers are leery of changing a tuning that is in place and the net effect is a worse product than what it could be. Moreover, tuning enabled on a given system might spread to other systems, where it might not be warranted at all.
Nevertheless, it is understood that customers who carefully observe their own system may understand aspects of their workloads that cannot be anticipated by the defaults. In such cases, the tuning information below may be applied, provided that one works to carefully understand its effects.
If you must implement a ZFS tuning parameter, please reference the URL of this document: