negative free blocks after mirror! [was: Re: mirror without
destroying existing contents]
stevefranks at ieee.org
Mon Mar 19 14:46:42 UTC 2007
On 3/17/07, Jonathan McKeown <jonathan at hst.org.za> wrote:
> On Friday 16 March 2007 21:48, Steve Franks wrote:
> > On 3/16/07, John Nielsen <lists at jnielsen.net> wrote:
> > > On Friday 16 March 2007 11:18, Steve Franks wrote:
> > > > I get the following:
> > > >
> > > > #gmirror label -v -b split -s 1024 data ad0
> > > > can't store metadata on ad0: operation not permitted.
> > >
> > > That most likely means that you currently have a filesystem on ad0
> > > mounted. If that's the case you should be glad that the OS was smarter
> > > than you. What steps had you taken prior to this?
> > It appears to say in the manpage that you can do this on a disk with
> > an existing filesys - would you expect it to work if the disk is
> > unmounted first, then?
> The way to do this is potentially a little risky but I haven't had a problem
> with it yet after setting up several mirrors on live fileservers. There is a
> sysctl called kern.geom.debugflags: if you set this to 16 it will allow you
> to change the mounted filesystem. Bear in mind that since the metadata for
> the mirror is written to the last sector of the disk, there is a small risk
> of data loss: if that sector contains data it will be overwritten.
> There's a thorough howto by Ralph Engelschall, and an OnLamp article by Dru
> Lavigne, with more details:
Yes, the origonal disk was pretty full, but, I suspect this is not a good thing:
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/ad0s1a 507630 95254 371766 20% /
devfs 1 1 0 100% /dev
/dev/ad0s1e 507630 30688 436332 7% /tmp
/dev/ad0s1f 152451398 5956408 134298880 4% /usr
/dev/ad0s1d 1444526 103600 1225364 8% /var
/dev/mirror/rainstones1 151368706 141135278 -1876068 101% /rainstone
How is that even possible?
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