On Wed, Mar 20, 2019 at 6:06 PM Dan van der Ster <d...@vanderster.com> wrote:
> 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. > Eek. Do you know if we have any tickets about that issue? It's easy to see how that happens but definitely isn't a good user experience! -Greg > > -- 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 >
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