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horiba
29-Nov-2012, 12:27
Is there any documentation as to what features of BTRFS are implemented and supported in SLES11-SP2? Or is it identical to the kernel version (3.0?)
Is it planned to backport specific BTRFS-Features from more recent kernels into SLES11-SP2? I'm specifically looking at quota support and/or qgroups.


I'm starting to set up a new server and if BTRFS won't support any sort of quotas (via quotad or subvolume) in any plannable time, then I need to reconsider (distribution or just the filesystem).

I found a featurelist in /usr/src/linux/Documentation/filesystems/btrfs.txt but I have no idea if this is in sync with the actual btrfs kernel module.

Additionally, YAST partitioner lets you activate quotas but then fails mounting the volume (because btrfs doesn't understand quota mount options) - a subsequent call to yast partitioner resulted in a kernel panic.

Automatic reply
06-Dec-2012, 14:30
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KBOYLE
06-Dec-2012, 18:33
horiba wrote:

>
> - Is there any documentation as to what features of BTRFS are
> implemented and supported in SLES11-SP2? Or is it identical to the
> kernel version (3.0?)
> - Is it planned to backport specific BTRFS-Features from more recent
> kernels into SLES11-SP2? I'm specifically looking at quota support
> and/or qgroups.

Have you seen:
Release Notes for SUSE Linux Enterprise Server 11 Service Pack 2

http://www.novell.com/linux/releasenotes/x86_64/SUSE-SLES/11-SP2/#fate-306585-1


> 3.1.1. Support for the btrfs File System
>
> Btrfs is a copy-on-write (CoW) general purpose file system. Based on
> the CoW functionality, btrfs provides snapshoting. Beyond that data
> and metadata checksums improve the reliability of the file system.
> btrfs is highly scalable, but also supports online shrinking to adopt
> to real-life environments. On appropriate storage devices btrfs also
> supports the TRIM command.
>
> Support
>
> With SUSE Linux Enterprise 11 SP2, the btrfs file system joins ext3,
> reiserfs, xfs and ocfs2 as commercially supported file systems. Each
> file system offers disctinct advantages. While the installation
> default is ext3, we recommend xfs when maximizing data performance is
> desired, and btrfs as a root file system when snapshotting and
> rollback capabilities are required. Btrfs is supported as a root file
> system (i.e. the file system for the operating system) across all
> architectures of SUSE Linux Enterprise 11 SP2. Customers are advised
> to use the YaST partitioner (or AutoYaST) to build their systems:
> YaST will prepare the btrfs file system for use with subvolumes and
> snapshots. Snapshots will be automatically enabled for the root file
> system using SUSE's snapper infrastructure. For more information
> about snapper, its integration into ZYpp and YaST, and the YaST
> snapper module, see the SUSE Linux Enterprise documentation.
>
> Migration from "ext" File Systems to btrfs
>
> Migration from existing "ext" file systems (ext2, ext3, ext4) is
> supported "offline" and "in place". Calling "btrfs-convert [device]"
> will convert the file system. This is an offline process, which needs
> at least 15% free space on the device, but is applied in place. Roll
> back: calling "btrfs-convert -r [device]" will roll back. Caveat:
> when rolling back, all data will be lost that has been added after
> the conversion into btrfs; in other words: the roll back is complete,
> not partial.
>
> RAID
>
> Btrfs is supported on top of MD (multiple devices) and DM (device
> mapper) configurations. Please use the YaST partitioner to achieve a
> proper setup. Multivolume/RAID with btrfs is not supported yet and
> will be enabled with a future maintenance update.
>
> Future Plans
>
> We are planning to announce support for btrfs' built-in multi
> volume handling and RAID in a later version of SUSE Linux Enterprise.
>
> Starting with SUSE Linux Enterprise 12, we are planning to
> implement bootloader support for /boot on btrfs.
>
> Transparent compression is implemented and mature. We are
> planning to support this functionality in the YaST partitioner in a
> future release.
>
> We are commited to actively work on the btrfs file system with
> the community, and we keep customers and partners informed about
> progress and experience in terms of scalability and performance. This
> may also apply to cloud and cloud storage infrastructures.
>
> Online Check and Repair Functionality
>
> Check and repair functionality ("scrub") is available as part of the
> btrfs command line tools. "Scrub" is aimed to verify data and
> metadata assuming the tree structures are fine. "Scrub" can (and
> should) be run periodically on a mounted file system: it runs as a
> background process during normal operation.
>
> The tool "fsck.btrfs" tool will soon be available in the SUSE Linux
> Enterprise update repositories.
>
> Capacity Planning
>
> If you are planning to use btrfs with its snapshot capability, it is
> advisable to reserve twice as much disk space than the standard
> storage proposal. This is automatically done by the YaST2 partitioner
> for the root file system.
>
> Hard Link Limitation
>
> In order to provide a more robust file system, btrfs incorporates
> back references for all file names, eliminating the classic
> "lost+found" directory added during recovery. A temporary limitation
> of this approach affects the number of hard links in a single
> directory that link to the same file. The limitation is dynamic based
> on the length of the file names used. A realistic average is
> approximately 150 hard links. When using 255 character file names,
> the limit is 14 links. We intend to raise the limitation to a more
> usable limit of 65535 links in a future maintenance update.
>
> For more information about btrfs, see the SUSE Linux Enterprise 11
> documentation.


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horiba
20-Dec-2012, 09:31
Hello Mr. Boyle,

Yes, I read through the release Notes. That's why I came here and asked. Maybe I overestimated "actively working with the community". I'm sorry for that.

So according to this answer, I just assume this means "No".

But please consider updating the YaST partitioner to not let the user enable quotas on btrfs. It's an impossible combination (yet) and could leave (under some circumstances) the system in an unbootable state.

KBOYLE
20-Dec-2012, 20:01
horiba wrote:

>
> Hello Mr. Boyle,
>
> Yes, I read through the release Notes. That's why I came here and
> asked. Maybe I overestimated "actively working with the community".
> I'm sorry for that.
>
> So according to this answer, I just assume this means "No".

When people ask questions here, we don't always know how much research
they may have already done. That is why I referred you to the
documentation.

You must remember that we are volunteers and while we may be active in
the Suse, Novell, and NetIQ forums, we don't work for these
organisations and therefore don't always know the internal workings of
a product or what product enhancements may be forthcoming.

>
> But please consider updating the YaST partitioner to not let the user
> enable quotas on btrfs. It's an impossible combination (yet) and could
> leave (under some circumstances) the system in an unbootable state.

I will pass on your comments and try to have a bug opened. If you
encounter a program defect or a security issue you can open a service
request yourself to have the issue corrected.


--
Kevin Boyle - Knowledge Partner
If you find this post helpful and are using the web interface,
show your appreciation and click on the star below...

horiba
21-Dec-2012, 07:57
horiba wrote:

You must remember that we are volunteers and while we may be active in
the Suse, Novell, and NetIQ forums, we don't work for these
organisations and therefore don't always know the internal workings of
a product or what product enhancements may be forthcoming.


I'm sorry again - I didn't mean to sound aggressive. As btrfs is a moving target, I hoped someone could specify what snapshot is in SLES11SP2 and if that snapshot is going to move in the lifetime of SLES11 (like the kernel did in SP2).




>
> But please consider updating the YaST partitioner to not let the user
> enable quotas on btrfs. It's an impossible combination (yet) and could
> leave (under some circumstances) the system in an unbootable state.

I will pass on your comments and try to have a bug opened. If you
encounter a program defect or a security issue you can open a service
request yourself to have the issue corrected.


I would love to send bug reports to SuSE, as service requests are not available for basic subscriptions. But that's a different discussion. (But please inform me if I overlooked a way to submit bugs outside of service requests)

jmozdzen
21-Dec-2012, 15:38
Hi horiba,

have you checked out http://support.novell.com/additional/bugreport.html?sourceidint=suplnav4a_bug ? It feels like kind of a black hole, but trust me, I've had responses when submitting there, without a support contract nor any special status. It just isn't guaranteed that somebody will get in touch with you. And yes, that's only for *defects*, not for feature requests.

Regards,
Jens

horiba
21-Dec-2012, 15:52
Hello Jens,

thank for the URL - no I wasn't aware of that. I'll bookmark that and will try and submit a bug after the holidays.

KBOYLE
21-Dec-2012, 18:11
horiba wrote:

> I'm sorry again - I didn't mean to sound aggressive.

No need to apologise. I didn't consider your comments to be at all
aggressive.

> As btrfs is a
> moving target, I hoped someone could specify what snapshot is in
> SLES11SP2 and if that snapshot is going to move in the lifetime of
> SLES11 (like the kernel did in SP2).

Suse doesn't normally comment on what enhancements will or will not be
included in future versions. Very often, when a new version is soon to
be released and they have committed to a specific feature set, they
will discuss some of the features in the upcoming release.

BrainShare is only a few weeks away. I would expect to hear some news
about what's coming in the next release. If you are able to attend,
that would be a great place to get answers to many of your questions.

If you can't make it, you can find many of the presentations online
shortly after the conference ends and others who have attended will be
able to share what they have learned.


--
Kevin Boyle - Knowledge Partner
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KBOYLE
24-Dec-2012, 19:25
horiba wrote:

> Additionally, YAST partitioner lets you activate quotas but then fails
> mounting the volume

I passed on this information and it appears to be a bug. Thank you for
bringing it to our attention.

I was given this link to pass on. It is the only other information
currently available.

https://www.suse.com/products/server/technical-information/#FileSystem

--
Kevin Boyle - Knowledge Partner
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KBOYLE
09-Jan-2013, 18:37
YAST partitioner lets you activate quotas but then fails mounting the volume (because btrfs doesn't understand quota mount options) - a subsequent call to yast partitioner resulted in a kernel panic.
A bug was opened:
https://bugzilla.novell.com/show_bug.cgi?id=797499

Quotas should be working in SLES11 SP3.