Re: Unionmount status?

From: Ric Wheeler
Date: Fri Apr 15 2011 - 12:31:54 EST

On 04/14/2011 10:54 AM, Michal Suchanek wrote:
On 14 April 2011 15:21, Ric Wheeler<ricwheeler@xxxxxxxxx> wrote:
On 04/14/2011 05:40 AM, Miklos Szeredi wrote:
On Thu, Apr 14, 2011 at 11:32 AM, Michal Suchanek<hramrach@xxxxxxxxxx>
I guess overlayfs includes the better part of unionmount and achieves
similar level of functionality in much smaller code size and is
actively developed.

This might make it the best candidate for inclusion so far.

It does not (yet?) support NFS which is one of the options commonly
used with union solutions, though.
NFS is supported as a lower (read-only) layer, but not as an upper
(read-write) layer.

I am not that concerned with the state of Val's repo, her intention was to
hand off the project cleanly to others and have them drive the code (that
hand off was the posting of the patch set). Several people (Ian, David
Howells and Al Viro) had been involved with union mounts recently, so we do
have reasonable candidates for a hand off.

One of the concerns with unionfs is the duplication of data. Union mounts
avoids this with that implementation. That might make unionfs more of a
burden for very large file systems, but probably not a concern for many use
Just to make things clear, what is a very large filesystem?

A heavily compressed DVD image?

Tens or hundreds of gigabytes? Terabytes?

Hundreds, thousands or hundreds of thousands of inodes?

Or is testing required to determine at what size the performance
becomes unacceptable?



Very large in the number of inodes more so than fs size...


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