[Linux-cluster] gfs_tool gettune

[Robert S Peterson]

On Fri, 2006-06-09 at 14:26 +0200, Olivier Thibault wrote: 
> Hello,
> 
> I am testing GFS 6.1 and have a question about the gettune command of 
> gfs_tool.
> If I do
> gfs_tool setflag inherit_directio my_directory
> then
> gfs_ttol gettune my_directory
> It displays :
> new_files_directio = 0
> 
> It is the same thing with the inherit_jdata flag and new_files_jdata
> 
> So my question is : is there any relation between these flags and what 
> gettune displays. Should'nt it display "new_files_directio = 1" ?
> 
> However, it seems that it impacts on the filesystem as my tests behave 
> differently depending on these flags.
> So, what are the tuneable options new_files_directio and new_files_jdata ?
> Is there somewhere any doc about all the tuneable parameters ?
> 
> Best regards,
> 
> Olivier

Hi Olivier,

Here's what's going on:
inherit_directio and new_files_directio are two separate things.
If you look at the man page, inherit_directio operates on a single
directory whereas new_files_directio is a filesystem-wide "settune"
value.  

If you do:

gfs_tool setflag inherit_directio my_directory

You're telling the fs that ONLY your directory and all new files
within that directory should have this attribute, which is why your
tests are acting as expected, as long as you're within that directory.
It basically sets an attribute on an in-memory inode for the directory.

If instead you were to do:

gfs_tool settune <mount point> new_files_directio 1

The value new_files_directio value would change for the whole
mount point, not just that directory.  Of course, you're seeing what
gfs_tool gettune my_directory is reporting for the global flag.

Regards,

Bob Peterson
Red Hat Cluster Suite