changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[Raz Ben-Jehuda(caro)]

I want to change the sunit,swidth of a file system which
was already created with a different tunnings, or at least
mount it with a different values.
Is it possible ?

thank you
-- 
Raz

Re: changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[Nathan Scott]

On Mon, 2007-03-26 at 22:25 +0200, Raz Ben-Jehuda(caro) wrote:
> I want to change the sunit,swidth of a file system which
> was already created with a different tunnings, or at least
> mount it with a different values.
> Is it possible ?

>From the XFS section in mount(8) ...

   sunit=value and swidth=value
       Used to specify the stripe unit and width for a RAID device or a
       stripe volume.  value must be specified in 512-byte block units.
       If this option is not specified and the filesystem was made on a
       stripe volume or the stripe width or unit were specified for the
       RAID device at mkfs  time,  then  the  mount  system  call  will
       restore the value from the superblock.  For filesystems that are
       made directly on RAID devices, these  options  can  be  used  to
       override  the  information  in  the superblock if the underlying
       disk layout changes after the filesystem has been created.   The
       swidth  option  is  required if the sunit option has been speci‐
       fied, and must be a multiple of the sunit value.


cheers.

-- 
Nathan

Re: changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[Raz Ben-Jehuda(caro)]

ahha...
but did you ever tried to set an sunit value bigger than the one
set during the mkfs.xfs ?

On 3/27/07, Nathan Scott <nscott@aconex.com> wrote:
> On Mon, 2007-03-26 at 22:25 +0200, Raz Ben-Jehuda(caro) wrote:
> > I want to change the sunit,swidth of a file system which
> > was already created with a different tunnings, or at least
> > mount it with a different values.
> > Is it possible ?
>
> >From the XFS section in mount(8) ...
>
>    sunit=value and swidth=value
>        Used to specify the stripe unit and width for a RAID device or a
>        stripe volume.  value must be specified in 512-byte block units.
>        If this option is not specified and the filesystem was made on a
>        stripe volume or the stripe width or unit were specified for the
>        RAID device at mkfs  time,  then  the  mount  system  call  will
>        restore the value from the superblock.  For filesystems that are
>        made directly on RAID devices, these  options  can  be  used  to
>        override  the  information  in  the superblock if the underlying
>        disk layout changes after the filesystem has been created.   The
>        swidth  option  is  required if the sunit option has been speci‐
>        fied, and must be a multiple of the sunit value.
>
>
> cheers.
>
> --
> Nathan
>
>


-- 
Raz

Re: changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[Shailendra Tripathi]

Raz Ben-Jehuda(caro) wrote:

> ahha...
> but did you ever tried to set an sunit value bigger than the one
> set during the mkfs.xfs ?
>
Yes, I do it many times and I have always got it right.

Re: changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[David Chinner]

On Tue, Mar 27, 2007 at 09:04:33AM +0200, Raz Ben-Jehuda(caro) wrote:
> ahha...
> but did you ever tried to set an sunit value bigger than the one
> set during the mkfs.xfs ?

Sure - but you've got to satisfy a whole heap of alignment
and size considerations when changing sunit e.g. AGs must be
stripe unit aligned and their size must be a whole multiple
of the stripe unit.

Hence any new value generally needs to be a multiple so
that filesystem alignment remains valid.

You might want to get a recent kernel, too, as it will
tell more about the reason why the mount with the new
sunit is failing (in dmesg).

Cheers,

dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group

Re: changing xfs file system tunnings(sunit,swidth) after mkfs.xfs

[Nathan Scott]

On Tue, 2007-03-27 at 09:04 +0200, Raz Ben-Jehuda(caro) wrote:
> EST)
> 
> 
> ahha...
> but did you ever tried to set an sunit value bigger than the one
> set during the mkfs.xfs ? 

I've not tried it, no - is that a trick question?  :)

cheers.

-- 
Nathan