[Ocfs2-users] Versions and features

[Werner Flamme]

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Sunil Mushran [01.03.2011 01:59]:
> On 02/28/2011 09:10 AM, Joel Becker wrote:
>> On Mon, Feb 28, 2011 at 02:07:16PM +0100, Werner Flamme wrote:
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>>> 
>>> Hi all,
>>> 
>>> last Friday my colleague (using Oracle's Linux 5) und me tried to
>>> get access to a shared OCFS2 volume. Since he claimed that he now
>>> has OCFS2 1.6, and I only have 1.4.3 (list below), we decided
>>> that I create the filesystem with
>>> --fs-feature-level=max-features.
>> If you want to share among differing versions, you want 
>> --fs-feature-level=max-compat.  max-features means "select the
>> newest features", which will be incompatible with ocfs2 1.4.
> 
> mkfs.ocfs2 manpage includes two sections titled feature
> compatibility and feature values. The former lists the features and
> when they were made available. You can use the feature values section
> to determine the feature the fs is missing in your distro version.
> 
> As Joel mentioned, that max-features is mostly meant for mainline. 
> Distros are always a step or two behind.

Sunil,

I see the compatibility list on the mkfs.ocfs2 manpage. But I still do
not see what features are available for any of us.

I this list, the kernel my colleague uses (2.6.18) is not mentioned, the
list starts with 2.6.20. So he has no OCFS2 at all? Nonsense, he has.
He uses OCFS2 1.4.8 as a kernel module, and the tools show version 1.6.
So he can use what features? Because of his kernel module it was local,
sparse, unwritten, and inline-data. But from the tools version he should
be able to use block64, xattr, and refcount also.

My kernel (2.6.32) does show up, but the version of my kernel module
(1.5) does not. My tools are version 1.4. So I should not be able to use
any feature that he can't. But this is not the case, some attribute that
my mkfs.ocfs2 introduced to the filesystem was the reason that he could
not mount it.

What might this attribute have been? How will we ever find out? Only
trial and error?

What about a %F in the query string of tunefs.ocfs2 telleing all
possible features for the installed combination of OCFS2 kernel module
and tools? %H and %M are nice, but they only show the flags that are
already applied. %F might show the features that are possible to handle.

Werner



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