similar to: Samba strict allocate = yes stops btrfs compression working

I set the C (NOCOW) and z (Not_Compressed) flags on a folder but the extent counts of files contained there keep increasing. Said files are large and frequently modified but not changing in size. This does not happen when the filesystem is mounted with nodatacow. I''m using this as a workaround since subvolumes can''t be mounted with different options simultaneously. ie. one with

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

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

I need everybody to go over this with a fine toothed comb since it is a pretty big change. I think it is right and it seems to come out right, but if it''s not it will mean we screw up O_DIRECT on snapshotted files with preallocated extents, so please, make sure it is correct :). --- Subject: [PATCH] Btrfs: rework can_nocow_odirect We are always doing the file extent lookup in here

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, I''ve been using btrfs for my root partition for about a month on archlinux and recently Ive started using the i3 window manager and starting X manually and I now boot to run level 3 (multi-user.target for systemd) and Ive noticed that booting archlinux on a btrfs root, there is a lot off hdd chatter after the login prompts are displayed, which doesnt happen with ext4 on root, so I

Hello, Trying to put together a list of TODO items for btrfs so we can update the wiki page fully. So far these things are on the list * Proper ENOSPC handling * O_DIRECT support (without checksumming) * AIO support * Subvolume quotas and inherited space usage information * Snapshot removal * QA Suite for automated regression testing * Reserved space for online fsck and the ability to add

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

Hi, I am using 2.6.36.3 kernel with btrfs, 512MB memory and a very slow disk, no special options for mounting btrfs except noatime. Now I found it very slow. When I rm a 5GB movie, it took 20 secs. -- 竹密岂妨流水过 山高哪阻野云飞 -- 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

After running ceph on XFS for some time, I decided to try btrfs again. Performance with the current "for-linux-min" branch and big metadata is much better. The only problem (?) I''m still seeing is a warning that seems to occur from time to time: [87703.784552] ------------[ cut here ]------------ [87703.789759] WARNING: at fs/btrfs/inode.c:2103

----- 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

Greetings all, I see the following issue during snap creation under IO: Transaction commit calls btrfs_start_delalloc_inodes() that locks the delalloc_inodes list, fetches the first inode, unlocks the list, triggers btrfs_alloc_delalloc_work/btrfs_queue_worker for this inode and then locks the list again. Then it checks the head of the list again. In my case, this is always exactly the same

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

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

Hi, I''ve noticed many files have blocks of plain nulls up to a few kb long, even files you wouldn''t normally expect to, like ELF executables. I know that with compression enabled these will compress very small, but that will have a reasonable hit on performance. How much of an overhead would it be to check all checksummed file extents to see if they match the checksum for a

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, this shown up today. I had to do a hard reboot as graceful hanged on sync(). ------------[ cut here ]------------ kernel BUG at fs/btrfs/delayed-inode.c:1466! invalid opcode: 0000 [#1] SMP CPU 10 Modules linked in: btrfs zlib_deflate lzo_compress ipmi_devintf autofs4 be2iscsi iscsi_boot_sysfs ib_iser rdma_cm ib_cm iw_cm ib_sa ib_mad ib_addr iscsi_tcp bnx2i cnic uio ipv6 cxgb3i libcxgbi

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

Hello, This is updated version of nodatacow patch. To check whether a given file extent is referenced by multiple snapshots, the checker walks down the fs tree through dead root and checks all tree blocks in the path. We can easily detect whether a given tree block is directly referenced by other snapshot. We can also detect any indirect reference from other snapshot by checking

Christoph Hellwig wrote: > There are a lot of variables when using qemu. > > The most important one are: > > - the cache mode on the device. The default is cache=writethrough, > which is not quite optimal. You generally do want to use cache=none > which uses O_DIRECT in qemu. > - if the backing image is sparse or not. > - if you use barrier - both in the host