[Gluster-users] xattr and ZFS

[Franco Broi]

On Mon, 2014-01-13 at 23:48 +0530, Vijay Bellur wrote: 
> On 01/13/2014 01:54 PM, Franco Broi wrote:
> > Hi all
> >
> > I have about 400TB of storage running dht on ZFS and want to change the
> > way the extended attributes are stored, assuming it's safe to do this in
> > ZFS version 0.6.2? I discovered by experimentation that if I remove the
> > attributes on the server, Gluster will remake them when a file is first
> > accessed. So the question is, would it be safe to simply delete all the
> > attributes from all files and just let Gluster remake them?
> >
> 
> GlusterFS does maintain state in extended attributes and manually 
> altering this state information has to be done very carefully.Removing 
> extended attributes for directories is not recommended as this can 
> potentially result in gfid split brains.
> 
> As far as files go in a distributed cluster (with no replication), the 
> gfid attribute can be removed and it gets re-created on access. What 
> other attributes do you intend removing?

I thought I might need to remove trusted.glusterfs.dht as well.

Which attributes get access when reading a directory? Does a stat on a
file need to read attributes?

I just did a test where I made 1000 directories over 8 bricks. I removed
trusted.gfid and trusted.glusterfs.dht and gluster remade them when I
did an ls -l from the client.

Currently an ls on a directory with a less than 100 files can take
minutes on our production storage system.

> 
> -Vijay