On Tue, Mar 19, 2019 at 9:43 AM Erwin Bogaard <erwin.boga...@gmail.com> wrote: > > Hi, > > > > For a number of application we use, there is a lot of file duplication. This > wastes precious storage space, which I would like to avoid. > > When using a local disk, I can use a hard link to let all duplicate files > point to the same inode (use “rdfind”, for example). > > > > As there isn’t any deduplication in Ceph(FS) I’m wondering if I can use hard > links on CephFS in the same way as I use for ‘regular’ file systems like ext4 > and xfs. > > 1. Is it advisible to use hard links on CephFS? (It isn’t in the ‘best > practices’: http://docs.ceph.com/docs/master/cephfs/app-best-practices/) > > 2. Is there any performance (dis)advantage? > > 3. When using hard links, is there an actual space savings, or is there some > trickery happening? > > 4. Are there any issues (other than the regular hard link ‘gotcha’s’) I need > to keep in mind combining hard links with CephFS?
The only issue we've seen is if you hardlink b to a, then rm a, then never stat b, the inode is added to the "stray" directory. By default there is a limit of 1 million stray entries -- so if you accumulate files in this state eventually users will be unable to rm any files, until you stat the `b` files. -- dan -- dan > > > > Thanks > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
