similar to: chattr +C vs. btrfs subvolume snapshot

----- 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 have a 3 disk raid1 filesystem mounted with nodatacow. I have a folder in said filesystem with the ''C'' NOCOW & ''Z'' Not_Compressed flags set for good measure. I then copy in a large file and proceed to make random modifications. Filefrag shows no additional extents created, good so far. A big thank you to the those devs who got that working. However, after

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

Hello, some time ago we discussed on #btrfs that the nocow attribute for files wasn''t working (around 3.3 or 3.4 kernels). That was evident by files fragmenting even with the attribute set. Chris mentioned to find a fix quickly for that, and posted some lines of change into irc. But recently someone mentioned that 3.6-rc looks like still not respecting nocow for files. Is there really

Hi, how can I do the following in a shell script: - check whether my file system supports cp --reflink? - check whether two files share the same data on disk, i.e. one has been created by cp --reflink of the other? Thank you! Thomas Koch -- 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

Add ''-C'' (nocow) option to vhd-util create. Btrfs has terrible performance when hosting VM images, even more when the guest in those VM are also using btrfs as file system. One way to mitigate this bad performance is to turn off COW attributes on VM files (since having copy on write for this kind of data is not useful). According to ''chattr'' manpage, NOCOW

While exploring some btrfs maintenance with respect to defragmenting I ran the following commands: # filefrag /path/to/34G.file /path/to/5.7G.file /path/to/34G.file: 2406 extents found /path/to/5.7G.file: 572 extents found Thinking those mostly static files could be less fragmented I ran: # btrfs filesystem defragment -c /path/to/34G.file # btrfs filesystem defragment -c /path/to/5.7G.file and

Enabling compression via chattr +c works with ZLIB (default method) only, right? Since there is no way to specify a compression method. Cannot I use LZO this way? Thanks in advance, -- w -- 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

Hello, This is the second attempt to bring in cross subvolume reflinks into btrfs. The first attempt was NAKed due to missing vfs mount checks and a clear description of what btrfs subvolumes are and probably also why cross subvolume reflinks are ok in the case of btrfs. This version of the patch comes from David and is in SUSE kernels since a long time, so it is tested and working. The patch

This testscript creates reflinks to files on different subvolumes, overwrites the original files and reflinks, and moves reflinked files between subvolumes. Originally submitted as testcase 302, changes are made based on comments from Eric: http://oss.sgi.com/archives/xfs/2013-03/msg00231.html Two new common/rc functions used in this script (_require_cp_reflink and _verify_reflink) have been

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?

It''s been nearly a year since the patches needed to implement a reflinked copy between subvolumes have been posted (http://permalink.gmane.org/gmane.comp.file-systems.btrfs/9865 ) and I still get "Invalid cross-device link" error with Linux 3.2.4 while I try to do a cp --reflink between subvolumes. This is a *very* useful feature to have (think offline file-level

The rule originally comes from nocow writing, but snapshot-aware defrag is a different case, the extent has been writen and we''re not going to change the extent but add a reference on the data. So we''re able to allow such compressed extents to be merged into one bigger extent if they''re pointing to the same data. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> ---

Hello, is it possible to set nodatacow on a per-file basis? I couldn''t find anything. If not, wouldn''t that be a great feature to get around the performance issues with VM and database storage? Of course cloning should still cause COW. Thanks, Ralf-Peter -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to

I want to eliminate the COW feature on all of my OS files. It is a nice feature for user files, but I don''t see a clear benefit for the actual OS files. And I suspect that COW induced fragmentation is causing or aggravating problems with my system including the boot open_ctree problem. I had planned to recursively chattr these files to "nodatacow" status but then I ran

What are the recommendations for running KVM images on BTRFS systems using kernel 3.4?  I saw older posts on the web complaining about poor performance, but I know a lot of work has gone into btrfs since then.  There also seemed to be the nocow option, but I didn''t find anything that said it actualy helped. Anybody have ideas? Thanks, Matt -- To unsubscribe from this list: send the line

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

WayneD's clone-dest patch seems to be working for me, it's available here: https://github.com/WayneD/rsync-patches/blob/master/clone-dest.diff I've written some very basic tests, which I've attached to this email, in case they are of use to anyone else. They're also available here: https://github.com/josephmaher/rsync Notes: Tests need to be run as root.

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

Hi list, I have a few large image files (VMware workstation VMDKs and TrueCrypt containers) which I routinely back up over the network to a btrfs raid10 volume via bigsync (https://code.google.com/p/bigsync/). The VM images in particular get really fragmented due to CoW, which is expected. I haven''t yet switched off CoW on the backups directory mainly to experiment and see what