On 11/18/2014 02:47 PM, John Andersen wrote:
On 11/18/2014 05:22 AM, Anton Aylward wrote:
You can set up a relation -- that is a HARD LINK -- between a file in the subvolume and elsewhere on the FS, possibly in another subvolume.
Are you sure of this?
http://comments.gmane.org/gmane.comp.file-systems.btrfs/7031
That thread is from 2010. It is now the end of 2014 and a lot more work has been done on BtrFS since then. Hardlinks did when I tried it back when I had a btrFS as everything all on the one disk and nothing else and a number of subvolumes. Lined from something under subvolume /home to subvolume /tmp. The 'causes bugs' doesn't make sense. If I had a single FS ext4Fs system I could hard link as in the example above, so why not on BtrFS? It does say in the docs that subvolumes are like directories :-) The last post at your reference says
If btrfs is to support deduplication one day, it has to work across subvolumes - otherwise, it won't be very useful.
I agree with that. Right now we do have tools, I forget the name, which walks a FS and looks for identical files to hardlink so as to reduce space used. Are you saying those tools won't work on BtrFS? I say they do. I say hard links do work. Here's my evidence. Right now I have BtrFS as ROOT and it has zypper snapshotting enabled so I have the following # btrfs subvolume list / ID 269 gen 343531 top level 5 path .snapshots ID 541 gen 341419 top level 269 path .snapshots/1/snapshot ID 542 gen 341419 top level 269 path .snapshots/2/snapshot ID 544 gen 341419 top level 269 path .snapshots/3/snapshot ID 545 gen 341419 top level 269 path .snapshots/4/snapshot ID 546 gen 343373 top level 269 path .snapshots/5/snapshot ID 547 gen 343378 top level 269 path .snapshots/6/snapshot Mainbox:~ # # ls -li /etc/hosts /.snapshots/6/snapshot/etc/hosts 863349 -rw-r--r-- 1 root root 1268 Jun 13 18:37 /etc/hosts 863349 -rw-r--r-- 1 root root 1268 Jun 13 18:37 /.snapshots/6/snapshot/etc/hosts # sum /etc/hosts /.snapshots/6/snapshot/etc/hosts 57395 2 /etc/hosts 57395 2 /.snapshots/6/snapshot/etc/hosts # cksum /etc/hosts /.snapshots/6/snapshot/etc/hosts 1962092743 1268 /etc/hosts 1962092743 1268 /.snapshots/6/snapshot/etc/hosts See, same size, same inode. I believe that constitutes a hard link. -- A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting frowned upon? -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org