On Sat, Oct 27, 2012 at 9:21 AM, Edward Ned Harvey (opensolarisisdeadlongliveopensolaris) < opensolarisisdeadlongliveopensola...@nedharvey.com> wrote:
> > From: Edward Ned Harvey (opensolarisisdeadlongliveopensolaris) > > > > Performance is much better if you use mirrors instead of raid. > (Sequential > > performance is just as good either way, but sequential IO is unusual for > most > > use cases. Random IO is much better with mirrors, and that includes > scrubs & > > resilvers.) > > Even if you think you use sequential IO... If you use snapshots... > Thanks to the nature of snapshot creation & deletion & the nature of COW, > you probably don't have much sequential IO in your system, after a couple > months of actual usage. Some people use raidzN, but I always use mirrors. > This may be the case if you often rewrite portions of files, so especially database usage, but if you generally write entire new files rather than modifying old ones, I wouldn't expect fragmentation to be that bad. The particular workload I have is like this, if a file is changed, it is overwritten entirely, so I went with raidz2 vdevs for more capacity. However, I'm not exactly pushing the limits of the pool performance, as my bottleneck is network. Tim
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