[linux-lvm] Rebuilding ext4 filesystem on an LV

[Malahal Naineni]

Stuart D. Gathman [stuart at bmsi.com] wrote:
> On Mon, 5 Jul 2010, Ken Bass wrote:
> 
> > But what bothers me is this message I get when I run e2fsck (which runs
> > fsck.ext4):
> > "e2fsck: Invalid argument while trying to open
> > /dev/mapper/VolGroupX-LogVolX"
> > 
> > Why am I getting that?
> 
> Not an expert, just a user, but I suspect that the ioerr is because
> the metadata for that LV is still pointing to the missing PV.  (I know
> you replaced it, but that doesn't update the LV.)

If everything went right, he should have the new PV in the LV, but looks
like something failed while activating the LV. Run 'dmsetup table' to
find out if the LV currently has new PV or old PV. You need
device-mapper knowledge for this.

> I suspect recovering the remaining data will require skipping the (huge)
> chuck of LV that was on the missing PV.  Or maybe the experts here
> will recommend editing the metadata to move the extent from the missing
> PV to the new PV.  The huge chunk will now have random data from the 
> new drive.  I would have initialized the new drive to zero (using the
> security erase) before using (maybe you did).

The best course of action would have been 'reading what ever data
available' from old disk to new disk. If the disk is absolutely
thrashed, then zero'ing the new PV may be better.