On 17.06.2014 22:37, Dave Chinner wrote: > On Tue, Jun 17, 2014 at 10:26:51AM +0200, Matthias Schniedermeyer wrote: > > Hi > > > > How seriously meant is "V5 isn't experimental anymore"? > > "Fully supported" isn't a clear enough statement? I guess that was a "selective memory"-bug on my side. > > I ask because the man-page only mentions the syntax to enable it by > > accident. A.k.a. the backport of ftype to V4. > > (man-page of xfsprogs 3.2.0 in Debian-SID) > > That's intentional. V5 superblocks are an implementation detail that > most users don't even need to know about. They care about the name > of the features they are enabling at mkfs time, not the details of > the on-disk implementation of those features. The question still stands. The crc-option is only mentioned "by accident". Without the ftype backport there would be no mention of the "feature crc". Furthermore i suspect that the ftype-feature also wouldn't be mentionted without the V4 backport. Which beggs the question, what other features are "burried" in V5 that aren't mentioned in the man-page. And are there any other "-m" options, because "-m" (asside from the ftype accident) is completly undocumented. > > And you still have to know that crc means V5. > > Why do you care about the format mkfs.xfs chooses for you - it's > based on the features you requested. V5 isn't magically faster than I find the crc feature relativly important. I personally had exprienced an USB enclosure(-model. As in i had several of those) that under rare circumstances flipped or cleared a single bit in a specific bit-pattern). Such corruption most likely ends up inside a data-file because most times there is more data than meta-data. But COULD happend inside the meta-data. Since that day i have nearly everything MD5(or SHA256)ed so i can at least detect if i have a data-corruption. Fortunatly that never happend again after i replaced that enclosure model. Which i can say with pretty high confidence. > V4 - there are many cases where it is slower due to CRC overhead > or the overhead of the larger inode it requires. So unless you > request a feature that requires it at mkfs time, you don't get that > format. Are there any feature besides crc/ftype in V5? But i guess for "-n type=1" i would get a V4 + feature_bit. And "-m crc=1" chooses V5 and i get ftype as a bonus (If i understand correctly). > In a year or so we'll change the mkfs default so that CRCs are > enabled by default, but we can't do that until all the distro's have > had time to pick up a kernel that fully supports the CRC feature.... OK. So V5 will be the future default. -- Matthias _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
