[Pvfs2-developers] question/help on extended attributes immutable, append, noatime AND pvfs2-xattr

[Sam Lang]

Hi Becky,

You're exactly right, both of the artifacts (bugs really) are just in  
the pfs2-xattr program.  We should fix that tool, but in general,  
you're probably better off doing testing with the lsattr and chattr  
linux utilities.  Those will let you set the append and noatime attrs  
on the same file.

The lsattr and chattr utils can only be run as root.  Also, keep in  
mind that once the immutable or append attributes are placed on a  
file, they can't be removed.  At this point it looks like its not  
possible to upgrade a file from append to immutable (perhaps a bug on  
the PVFS server).  In order to remove the attributes, the entire file  
must be deleted.  The noatime attr can be removed at any point.

-sam

On Nov 10, 2008, at 8:59 AM, Becky Ligon wrote:

>
> Hello to all:
>
> I am adding a "mirror" capability to PVFS2 and am using the setting  
> of the
> immutable flag as the event in which a copy(ies) of the file is
> created...just as a start.  I am new at this game and need some help!
>
> I have been using the pvfs2-xattr program to understand how the  
> immutable
> flag behaves and would like someone to confirm or clarify the behavior
> that I am seeing.  My observations:
>
> 1.  immutable, append, and noatime appear to be mutually exclusive
> characteristics.  This makes sense to me with the exception that  
> noatime
> would seem to apply to either immutable or append files.  Thus, if you
> turn on one characteristic, the other two are turned off.  Is this
> behavior expected?  Or, is this behavior simply a product of the
> pvfs2-xattr program?
>
> 2.  When you turn off ANY of the three characteristics, then NONE of  
> the
> three characteristics are turned on.  For example, if you have  
> immutable
> turned on and then you turn off append, then the result is that  
> immutable
> is turned off.  Is this a defect with pvfs2-xattr?  Shouldn't  
> immutable
> only be turned off IFF the immutable option was turned off?
>
> If someone can clarify what I'm seeing, I would appreciate it.
>
> Thanks,
>
> Becky Ligon
>
> -- 
> Becky Ligon
> PVFS Developer
> Clemson University
> 864-656-3865
>
>
>
> -- 
> Becky Ligon
> PVFS Developer
> Clemson University
> 864-656-3865
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