On Jan 18, 2010, at 3:25 PM, Erik Trimble wrote: > Given my (imperfect) understanding of the internals of ZFS, the non-ZIL > portions of the reserved space are there mostly to insure that there is > sufficient (reasonably) contiguous space for doing COW. Hopefully, once BP > rewrite materializes (I know, I'm treating this much to much as a Holy Grail, > here to save us from all the ZFS limitations, but really...), we can > implement defragmentation which will seriously reduce the amount of reserved > space required to keep up performance.
[Richard pauses to remember the first garbage collection presentation by a bunch of engineers dressed as garbage men... they're probably still working at the same job :-)] There is still some work being done on the allocation front. From my experience with other allocators (and garbage collectors) I'm sure the technology will change right after it gets near perfect and we'll have to adapt again. For example, b129 includes a fix for CR6869229, zfs should switch to shiny new metaslabs more frequently. http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6869229 I think the CR is worth reading if you have an interest in allocators and performance. > Once all this gets done, I'd think we seldom would need more than a GB or two > as reserve space... I hope :-) -- richard _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
