Oh, and one other thing ...
--- On Fri, 9/21/12, Jason Usher <jushe...@yahoo.com> wrote: > > It shows the allocated number of bytes used by the > > filesystem, i.e. > > after compression. To get the uncompressed size, > multiply > > "used" by > > "compressratio" (so for example if used=65G and > > compressratio=2.00x, > > then your decompressed size is 2.00 x 65G = 130G). > > > Ok, thank you. The problem with this is, the > compressratio only goes to two significant digits, which > means if I do the math, I'm only getting an > approximation. Since we may use these numbers to > compute billing, it is important to get it right. > > Is there any way at all to get the real *exact* number ? I'm hoping the answer is yes - I've been looking but do not see it ... > Ok. So the dedupratio I see for the entire pool is > "dedupe ratio for filesystems in this pool that have dedupe > enabled" ... yes ? > > > > > Also, why do I not see any dedupe stats for the > > individual filesystem ? I see compressratio, and I > see > > dedup=on, but I don't see any dedupratio for the > filesystem > > itself... > > > Ok, getting back to precise accounting ... if I turn on > dedupe for a particular filesystem, and then I multiply the > "used" property by the compressratio property, and calculate > the real usage, do I need to do another calculation to > account for the deduplication ? Or does the "used" > property not take into account deduping ? So if the answer to this is "yes, the used property is not only a compressed figure, but a deduped figure" then I think we have a bigger problem ... You described dedupe as operating not only within the filesystem with dedup=on, but between all filesystems with dedupe enabled. Doesn't that mean that if I enabled dedupe on more than one filesystem, I can never know how much total, raw space each of those is using ? Because if the dedupe ratio is calculated across all of them, it's not the actual ratio for any one of them ... so even if I do the math, I can't decide what the total raw usage for one of them is ... right ? Again, if "used" does not reflect dedupe, and I don't need to do any math to get the "raw" storage figure, then it doesn't matter... > > > Did turning on dedupe for a single filesystem turn > it > > on for the entire pool ? > > > > In a sense, yes. The dedup machinery is pool-wide, but > only > > writes from > > filesystems which have dedup enabled enter it. The > rest > > simply pass it > > by and work as usual. > > > Ok - but from a performance point of view, I am only using > ram/cpu resources for the deduping of just the individual > filesystems I enabled dedupe on, right ? I hope that > turning on dedupe for just one filesystem did not incur > ram/cpu costs across the entire pool... I also wonder about this performance question... Thanks. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
