similar to: /var/lib/libvirt/images on BTRFS (it works!)

Hello, I habe the problems described in here https://btrfs.wiki.kernel.org/index.php/Gotchas: Files with a lot of random writes can become heavily fragmented (10000+ extents) causing trashing on HDDs and excessive multi-second spikes of CPU load on systems with an SSD or large amount a RAM. On servers and workstations this affects databases and virtual machine images. The nodatacow mount option

As of the latest updates to anaconda and grub2 for Fedora 18, it is now possible to install with /boot as a btrfs subvolume. The way that grub2 is handling this is the "reach down" to the files it needs as if the subvolume was a directory. Is this OK? At this point I am not worried about snapshots or any other complexities. If the subvolume name is known. should grub2 be able to

Although for most time, int is enough for subvolid, we should ensure safety in theory. Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com> Reviewed-by: Miao Xie <miaox@cn.fujitsu.com> --- fs/btrfs/super.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index cc00295..d82391d 100644 --- a/fs/btrfs/super.c

Allows to specify one or multiple device=/dev/foo options during mount so that ioctls on the control device can be avoided. Especially useful when trying to mount a multi-device setup as root. Signed-off-by: Christoph Hellwig <hch@lst.de> Index: btrfs-unstable/super.c =================================================================== --- btrfs-unstable.orig/super.c 2008-06-10

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:

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

Hi Seto, please could you update also the man page too ? Why it was not provided a way to clear a *single* flag ? To me it seems a bit too long to clear all the flag (btrfs mount-option clear) and then set the right one. As user interface I suggest something like chmod: btrfs mount-option set +ssd,skip_balance -nodatacow /dev/sdX or btrfs mount-option set =ssd,skip_balance,nodatacow

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

I am a relative newcomer to using extlinux. I am running Fedora 20 which means I am using syslinux 4.05. When I noticied that all of your documentation said that booting off ext234 and btrfs was supported, I gave it a try. Indeed, this does work with the boot files and the extlinux directory installed into the btrfs (root) volume. Has any thought been given to supporting supporting

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

Hi! Today I converted my /home from Ext4 to BTRFS by reformatting and copying all over again. I created the filesystem with -l 16384 -n 16384 -d single -m single on an logical volume Intel SSD 320 and mount with compress=lzo,spacecache. Current state: merkaba:~> btrfs filesystem show failed to read /dev/sr0 Label: ''home'' uuid: […] Total devices 1 FS bytes used

The code to parse btrfs subvol entries in /etc/fstab failed if the entry had more than one comma-separated option, for example: /dev/sda4 /home btrfs rw,user,subvol=foo 0 0 This commit fixes that code to use Augeas correctly. Fixes commit 7ba0e10501f23358c38939930d613bf2393d744d. Reported by: Zhongfu Li https://bugs.launchpad.net/ubuntu/+source/libguestfs/+bug/1615337 ---

On Fri, Oct 10, 2014 at 01:47:01PM +0200, Olaf Hering wrote: > > Is btrfs subvol support failing just for me? Looks like nothing adds the > required '@/' string. virt-ls uses the first variant of the command: > > ><rescue> mount -vo subvol=var/spool,ro /dev/sda2 /sysroot/ > [ 113.852047] BTRFS info (device sda2): disk space caching is enabled > [

I'm experimenting with btrfs-send. Previously (2014-09-26), I did my first btrfs-send on a subvol, and that worked fine. Today, I tried to send a new snapshot. Unfortunately, I realized part way through that I forgot to specify the parent to only send a delta, and killed the send with ^C. On the destination, I'm left with: ~$ sudo btrfs subvol list /var/media/backups/venus/home/ ID 2820

To reproduce the bug: # mount -o nodatacow /dev/sda7 /mnt/ # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB) copied, 0.000136115 s, 30.1 MB/s # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 conv=notrunc oflag=direct dd: writing `/mnt/tmp'': Input/output error 1+0 records in 0+0 records out btrfs_ordered_update_i_size() may return

>From 03115f064be2e074d84f4e2105d2cdebde10f6ba Mon Sep 17 00:00:00 2001 From: Yi Yang <yi.y.yang at intel.com> Date: Tue, 12 Jul 2011 14:53:50 +0800 Subject: [PATCH] Use a general way to get the default subvolume for btrfs --- extlinux/btrfs.h | 105 +++++++++++++++++++ extlinux/main.c | 304 ++++++++++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 377 insertions(+),

I was Googling around for ways to check fragmentation on Btrfs, and I came across the ''filefrag'' command. Even though it is a ext2/3 command, it seems to work on Btrfs files since it uses the FIEMAP ioctl to determine the number of extents. From a bash prompt, I found I could examine large sections with something like: # for file in $(find <PATH/TO/BTRFS/VOL/> -type f);

Right now inode cache inode is treated as the same as space cache inode, ie. keep inode in memory till putting super. But this leads to an awkward situation. If we''re going to delete a snapshot/subvolume, btrfs will not actually delete it and return free space, but will add it to dead roots list until the last inode on this snap/subvol being destroyed. Then we''ll fetch deleted

This commit adds a command line option to enable sending streams which make use of the new end-cmd semantic if multiple snapshots are sent back-to-back. The goal is to use the <end cmd> as an indication to stop reading the input stream. So far, the receiver could only use EOF to recognize the end. If the new command line option ''-e'' is set, this commit requires a kernel

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