similar to: hard links across snapshots/subvolumes are actually a bad idea.

It seems that the BTRFS_IOC_CLONE ioctl fails when trying to do a cross-subvolume clone of a file. Chris Mason suggested in the past ([1]) that this should be possible. Am I missing something? [1] http://kerneltrap.org/mailarchive/linux-btrfs/2010/6/10/6884911 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to

Hi, There''s been discussion before on this list on the very small number of hard links supported by btrfs.[1][2] In those threads, an often asked question has been if there''s a real world use case the limit breaks. Also it has been pointed out that a fix for this would need a disk format change. As discussed in bug #15762 [3], there are certainly real-world use cases this

Glück Auf! I know its been discussed more then ones, but as a user I really would like to see the patch for allowing this in the kernel. Some users tested this patch successfully for weeks or months in 2 or 3 kernel versions since then, true? I''d say by creating a snapshot, it''s nothing else in the end. More then one file or tree sharing the same data on disc, or am I wrong?

I realise that the hard link limit is in the queue to fix, and I read the recent thread as well as the older (october I think) thread. I just wanted to note that BackupPC *does* in fact run into the hard link limit, and its due to the dpkg configuration scripts. BackupPC hard links files with the same content together by scanning new files and linking them together, whether or not they started

Here are patches to do offline deduplication for Btrfs. It works well for the cases it''s expected to, I''m looking for feedback on the ioctl interface and such, I''m well aware there are missing features for the userspace app (like being able to set a different blocksize). If this interface is acceptable I will flesh out the userspace app a little more, but I believe the

----- Forwarded Message ----- From: "Stefan Hajnoczi" <stefanha@redhat.com> To: "Eric Sandeen" <sandeen@redhat.com> Cc: virt-devel@redhat.com, "Kevin Wolf" <kwolf@redhat.com> Sent: Friday, November 22, 2013 9:20:51 AM Subject: [virt-devel] btrfs NOCOW for VM disk images Hi, In upstream QEMU we''re discussing patches that set the NOCOW flag

I''m looking to try BTRFS on a SSD, and I would like to know what SSD optimizations it applies. Is there a comprehensive list of what ssd mount option does? How are the blocks and metadata arranged? Are there options available comparable to ext2/ext3 to help reduce wear and improve performance? Specifically, on ext2 (journal means more writes, so I don''t use ext3 on SSDs,

Hi all, Just a quick question but can''t find an obvious answer. Can I create/convert a existing (btrfs) directory into a subvolume? It would be very helpful when transferring ''partitions'' into btrfs. I found a similar question way back in google, but that site is down now generally. Thanks in advance. -- To unsubscribe from this list: send the line

I''m wondering is space really freed after deleting large subvolume? Will space be immediately available to other data like other subvolumes? -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html

Hi, I have 4 machines, all converted to BTRFS about 6 months ago, now all running Ubuntu Quantal with kernel 3.5.0-17 The matter is that all these machines are now getting slower and slower everyday, every disk access causing the disk to be 100% busy for long periods, to the point that I''m now seriously considering migrating everything back to ext4... From the start BTRFS was "not

Hi, I have a box with / and /home being subvolumes from the same btrfs filesystem. /etc/fstab: UUID=c0686... / btrfs subvol=root,x-systemd.device-timeout=0 1 1 UUID=c0686... /home btrfs subvol=home,x-systemd.device-timeout=0 1 1 ... / is initially mounted readonly by the initramfs, and then after switching to the real system, /home is attempted to be mounted in parallel with /

Hello, I''d like to know if there has been any discussion about adding a new feature to write (add) data at an offset, but without overwriting existing data, or re-writing the existing data. Essentially, in-place addition/removal of data to a file at a place other than the end of the file. Some possible use-cases of such a feature would be: (a) Databases (currently hack around this by

What happens if you set an individual file inside a subvolume as nocow (chattr +C) and then take a snapshot of that subvolume and modify the file in both? Will btrfs now ignore the nocow attribute completely or will it do "as few copies as possible"? (I''d love to know if it''s possible to visualize the fragmentation of a single file.) -- To unsubscribe from this list:

NFS needs a unique identifier for a filesystem to be able to export it. This can be set by the admin (fsid= in /etc/exports) but that is a hassle and it is best to set it automatically. nfs-utils currently uses the UUID returned by libblkid if that works, or the fsid returned by statfs64 if libblkid finds nothings and fsid is non-zero. Otherwise it uses device major/minor. This

Is there a way to mix RAID 1 and 0 in different subvolumes? I am a new user to btrfs and would like to protect the important files with mirroring, but have a bulk area that is striped for speed and size. For example I want / and /home to be mirrored, but /media can just be striped as it is all data I can easily recreate. I see an item in the Project_ideas wiki entry called "Online raid

Setting subvolume/snapshot readonly has been missing for a long time. With this patch, we can set a subvolume/snapshot readonly via: o btrfs subvolume set-ro <path> Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com> --- cmds-subvolume.c | 40 ++++++++++++++++++++++++++++++++++++++++ ioctl.h | 7 +++++++ 2 files changed, 47 insertions(+), 0 deletions(-) diff --git

As I''ve been using btrfs with an external USB drive, I wonder how to handle efficiently the compression setting. When I plug a drive in to ubuntu, it is automatically mounted. Its mounted without the compression option as its not in fstab. I don''t see it as desirable to install each usb drive in fstab on each computer that it may be used just so that compression is

Not sure if it''s anything interesting - I had the following entry in dmesg a few days ago, on a server with 32 GB RAM. The system is still working fine. [1878432.675210] btrfs-qgroup-re: page allocation failure: order:5, mode:0x104050 [1878432.675319] CPU: 5 PID: 22251 Comm: btrfs-qgroup-re Not tainted 3.11.0-rc7 #2 [1878432.675417] Hardware name: System manufacturer System Product

If we change our default subvolume, btrfs receive will fail to find subvolume. To fix this problem, i have two ideas. 1.make btrfs snapshot ioctl support passing source subvolume''s objectid 2.when we want to using interval subvolume path, we mount it other place that use subvolume 5 as its default subvolume. We''d better use the second approach because it won''t bother

Hi All, the following patches implement the recursively snapshotting and deleting of a subvolume. To snapshot recursively you must pass the -R switch: # btrfs subvolume create sub1 Create subvolume ''./sub1'' # btrfs subvolume create sub1/sub2 Create subvolume ''sub1/sub2'' # btrfs subvolume snapshot -R sub1 sub1-snap Create a snapshot of