Create a mirror on disk with valid data

[Danny Howard]

On Sat, Sep 17, 2005 at 11:17:00AM +0700, Victor Sudakov wrote:
> Danny Howard wrote:
> > 
> > I have only ever mirrored disks with data on them.  Its a question of
> > bootstrap - does the mirror comes first or does the data you are going
> > to mirror come first?
> 
> Suppose the disk has valuable data in the last sector and you are
> going to create a mirror from this disk. What is going to happen when
> the last sector is overwritten with the mirror metadata? Your data will
> be lost, right? Suppose you need to access the last sector, access
> will be denied, right?

>From what I have read, the gmirror stuff uses a sector of the disk that
isn't used at the end, and if you format a disk in such a way that that
free sector is unavailable, you can not set up a gmirror.

If you find a scenario in which setting up a gmirror destroys data on a
disk, then please use send-pr to file a bug, so that that issue can be
fixed.

But, if your question is "does gmirror do evil things to existing data"
then I'll answer that I and others have gmirrored quite a few disks with
existing data and I'm not aware that anybody has been bitten by your
hypothesis.

Thanks,
-danny

-- 
http://dannyman.toldme.com/