[Gluster-users] thoughts on disk usage (df) output

[Krishna Srinivas]

Keith,

On Sun, Aug 3, 2008 at 8:32 AM, Keith Freedman <freedman at freeformit.com> wrote:
> This probably is better posed in the gluster-devel mailing list, and
> it's not a big deal and probably not something that needs to be
> solved, but I felt i should share the situation, just in case anyone
> else needs to do the same thing.
>
>
> So, I have 2 servers AFRing eachother.  They had the same amount of
> disk space but on different sized drives.
> Since gluster just sits on top of the underlying filesystem, what I did was:
>
> /dev/disk1 mounts to /gluster
> /dev/disk2 mount to /gluster/extra
>
> in the gluster translator, I specify the source path as /gluster and
> mount it to /home
>
> so in home I now see /home/extra and /home/(all the other dirs)
> This works fine AFR seems to be happy.
>
> When I do a df, however, /home is reported as the same as /dev/disk1
> rather than the combined values of /dev/disk1 and /dev/disk2
> I certainly understand why, and realize it'd be quite difficult to
> resolve this issue.
>
> It's not very full, so my concern is..  might gluster
> overfill  /home/extra because it thinks it has more space than it
> does, or might it think the disk is full when it's not and there's
> still room to write files (if they're being written in /home/extra).

Yes this can happen as glusterfs wont have any idea that another
disk partition has been mounted in one of the sub directories.

You could use LVM and combine the two disks.

Regards
Krishna

>
> As a testament to gluster.. this non-standard configuration does seem
> to work just fine, and the  underlying file systems are actually even
> different..  one is xfs the other is ext3 (mounted with user_xattr option).
>
> Ultimately, I'll sanitize this configuration, but the fact that it
> works so well now is impressive.
>
> Keith
>
>
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