Re: [vserver] vhashify not working? - 2.6.27.14-vs2.3.0.36.4

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Thu 02 Apr 2009 - 22:47:33 BST
Message-ID: <20090402214732.GA26520@MAIL.13thfloor.at>

On Thu, Apr 02, 2009 at 08:36:40AM -0400, John A. Sullivan III wrote:
>
>
> On Thu, 2009-04-02 at 13:04 +0200, Herbert Poetzl wrote:
> > On Tue, Mar 31, 2009 at 09:41:06AM -0400, John A. Sullivan III wrote:
> > > On Tue, 2009-03-31 at 08:40 +0000, Christoph Lukas wrote:
> >
> > [stuff zapped]
> >
> > > Yes, the numbers match and they also match the size of the space
> > > consumed on the thinly provisioned ZFS zvol on which they reside
> > > (28.1 GB):
> >
> > there is no attribute support for ZFS, and thus
> > there is no barrier and no CoW-link breaking
> > available either ... your options are:
> >
> > - sponsor development for ZFS/xattrs
> > - have immutable hardlinks without CoW link breaking
> > - move to a supported filesystem
> >
> > best,
> > Herbert
> <snip>

> Thanks, Herbert, but the files aren't sitting on ZFS.
> I wasn't as clear as I should be.

> ZFS is the underlying file store on the SAN but it exporting
> block devices to VServer which are formatted as ext3 - sort
> of like a block image file in KVM.

okay, so you are using ZFS (on the SAN) to store a
file, which gets exported (via ??) as block device
to the host, which in turn, uses an ext3 filesystem
to contain guest data ...

> All the vservers are sitting in the same pseudo block device
> and all as ext3.

they are created in the same filesystem, which
is linked from the hash store?

> I wouldn't think that would ZFS would come into play but,
> as I said, I know little of the internals

no, in this case the ZFS and its features are not
really used and thus not relevant ... the way the
space arrives at the host might be relevant, but
doesn't matter for the unification case

double check that files which _should_ definitely
be shared and identical (stat /path/to/guest/bin/bash)
are indeed identical in all aspects, and see if they
are shared (link count ~ #guests) after hashification

HTH,
Herbert

> - John
> --
> John A. Sullivan III
> Open Source Development Corporation
> +1 207-985-7880
> jsullivan@opensourcedevel.com
>
> http://www.spiritualoutreach.com
> Making Christianity intelligible to secular society
Received on Thu Apr 2 22:47:44 2009

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