Ext3 users - Mar 2006 - FC5: "ext_attr" and "large_file" features for ext3 file systems ???

Hi,

 Fedora Core ext3 file systems newbie questions:

 Just interested in the Linux ext3 features but got
confused with "large_file" and "ext_attr".

 First, what's the "large_file" feature REALLY means?
For file systems created with same commands and
options some file systems have it on while some not.
It is said that the feature is automatic -- If there
is a large file then it is lit on otherwise it is off.
Then, what's the size of "large file" to light this
feature on? 2GB, or 2TB? or varies with the kernel
version?

 Second, the "ext_attr" feature seems another
automatic one: it only appears after the first
"setfacl" command runs on the file system and then the
feature will keep on there forever even ACL is
removed. What's the indication of "ext_attr" feature
and what are the reasons behind to have this feature?

Thanks a lot.


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ext_attr , is for extendended attributes , things like access control
are not part of an ext3 FS by default ,if you want acl ,then the
ext_attr feature will tell you.

large_file is for files beyond 2TB ,but when it swtiches on
automatically , i have no idea..

Digz


On Tue, 2006-03-28 at 13:52 -0800, Robinson Tiemuqinke
wrote:
> Hi,
> 
>  Fedora Core ext3 file systems newbie questions:
> 
>  Just interested in the Linux ext3 features but got
> confused with "large_file" and "ext_attr".
> 
>  First, what's the "large_file" feature REALLY means?
> For file systems created with same commands and
> options some file systems have it on while some not.
> It is said that the feature is automatic -- If there
> is a large file then it is lit on otherwise it is off.
> Then, what's the size of "large file" to light this
> feature on? 2GB, or 2TB? or varies with the kernel
> version?
> 
>  Second, the "ext_attr" feature seems another
> automatic one: it only appears after the first
> "setfacl" command runs on the file system and then the
> feature will keep on there forever even ACL is
> removed. What's the indication of "ext_attr" feature
> and what are the reasons behind to have this feature?
> 
> Thanks a lot.
> 
> 
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around 
> http://mail.yahoo.com 
> 
> _______________________________________________
> Ext3-users mailing list
> Ext3-users at redhat.com
> https://www.redhat.com/mailman/listinfo/ext3-users

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Hi,

On Tue, 2006-03-28 at 13:52 -0800, Robinson Tiemuqinke wrote:
>  First, what's the "large_file" feature REALLY means?
> Then, what's the size of "large file" to light this
> feature on? 2GB, or 2TB? 
2GB.
>  Second, the "ext_attr" feature seems another
> automatic one: it only appears after the first
> "setfacl" command runs on the file system and then the
> feature will keep on there forever even ACL is
> removed. What's the indication of "ext_attr" feature
> and what are the reasons behind to have this feature?
They are there simply to indicate that a given feature is present on the
filesystem.  They prevent old versions of the kernel and/or e2fsck tools
from mistakenly operating on a filesystem with newer features,
potentially corrupting things on disk or returning incorrect file
contents.

All remotely recent kernels have large file support for ext3, and all
2.6 ones (and many vendor-supplied 2.4 ones) have ext_attr, so you have
to be running something pretty old to run into compatibility problems
with either of those features.

--Stephen