On Tue, 24 Apr 2012, Tim Connors <tconnors@rather.puzzling.org> wrote:
ZFS is fragmentation city, pretty much by design - that's what you get with COW and variable block sizes.
Yeah, that's what I feared. Why can't someone invent a perfect filesystem (that's why I didn't invent ZFS[1] :), dagnamit?
I have the impression that ZFS is like NetApp WAFL in that it streams out contiguous writes for separate files. So it makes writes contiguous at the expense of making later reads fragmented. For situations where write performance is more of a bottleneck than read performance (which means every mail server, most database servers, and a significant portion of all other servers) this is a good thing! You can improve read performance in most cases by adding more cache, ZFS has new caching methods and RAM is constantly dropping in price (32G for a personal workstation isn't impossible nowadays). Write performance has been a serious problem for years.
you close a bunch of tabs. You can't shrink unless brk() takes a negative number and all your allocations were at the start of your heap. I wouldn't have invented *THAT* API!
That's why modern systems have malloc() calling mmap() not brk(). -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/