Re: [linux-lvm] filesystem corruption...

["Heinz J . Mauelshagen" <mauelshagen@sistina.com>]

On Thu, Feb 28, 2002 at 10:07:03AM +0100, Anders Widman wrote:
> 
> > On Thu, Feb 28, 2002 at 09:35:53AM +0100, Anders Widman wrote:
> >> 
> >> >> On Wednesday, February 27, 2002 04:42:28 PM -0700 Andreas Dilger <adilger@clusterfs.com> wrote:
> >> 
> >> >>> On Feb 27, 2002  23:36 +0100, Anders Widman wrote:
> >> >>>> Unfortunatley, something went seriously wrong. I can't mount the disk
> >> >>>> any more, or use reiserfsck. They (mount/reiserfsck) say there isn't
> >> >>>> a valid filesystem on the device. Vgscan does however find all devices
> >> >>>> and can activate the volume group, but reiserfsck doesn't work.
> >> >>>> 
> >> >>>> What should I do to be able to save a s much data as possible?
> >> >>> 
> >> >>> dd if=/dev/vg/lv of=/new/disk conv=sync,noerror
> >> 
> >> >> Then we should be able to use debugreiserfs and reiserfsck to 
> >> >> find a copy of the super in the log, or just recreate it.
> >> 
> >> >> -chris
> >> 
> >> > So. How much space would this require on the 'new' disk? The same
> >> > amount as the entire LV? If that is, it would be impossible (for me,
> >> > economically) to do this.
> >> 
> >> > The disk with bad blocks is 80GB, and I have a "spare" 80GB disk, but
> >> > not more.
> >> 
> >> > //Anders
> >> 
> >> Oh, I forgot to ask how I can recover the filsystem
> >> header/suprtblock.. What exactly is "dd if=/dev/vg/lv of=/new/disk
> >> conv=sync,noerror" doing to the data, except copying it to the new
> >> device?
> 
> > It copies all it can read to another sane device so that youe don't loose
> > more data if your drive turns worse.
> 
> > After that, you want to use "reiserfsck --rebuild-sb /dev/vg/lv".
> 
> Ok. Unfortunatley, I can't get enough storage to copy all data. Would
> it be possible to just copy the data from the broken disk to a new,

So /dev/vg/lv is bigger than that disk?

> identical disk (I have a "spare" disk of the same model), and then
> rebuild the filsystem?

Well, then pvcreate the spare disk, add it to your VG and
"pvmove -i /dev/BrokenDisk /dev/SaneDisk" data over.

You need to have recent LVM 1.0.3 tools in order to use the -i option of
pvmove, which ignores read errors and you need to patch liblvm.h with the
following one to make pvmove work correctly.

After that repair the filesystem in /dev/vg/lv.

diff -u -B -r1.43 -r1.44
--- LVM/tools/lib/liblvm.h      18 Feb 2002 16:37:18 -0000      1.43
+++ LVM/tools/lib/liblvm.h      20 Feb 2002 10:49:14 -0000      1.44
@@ -93,10 +93,10 @@
 #include <time.h>
 #include <limits.h>
 #ifdef _G_LSEEK64
-int lseek64 ( unsigned int, unsigned long long, unsigned int);
+loff_t lseek64 ( int, loff_t, int);
 #define llseek lseek64
 #else
-int llseek ( unsigned int, unsigned long long, unsigned int);
+loff_t llseek ( int, loff_t, int);
 #endif

 #include <sys/ioctl.h>
@@ -130,7 +130,7 @@
 #define        LVMTAB                  "/etc/lvmtab"   /* LVM table of VGs */
 #define        LVMTAB_DIR              "/etc/lvmtab.d" /* storage dir VG data */
 #define        LVMTAB_MINSIZE   ( sizeof ( vg_t) + sizeof ( lv_t) + sizeof ( pv_t))
-#define        LVM_DEV                 "/dev/lvm"
+#define        LVM_DEV                 LVM_DIR_PREFIX "lvm"
 #define        VG_BACKUP_DIR           "/etc/lvmconf"
 #define        DISK_NAME_LEN           8
 #define        LV_MIN_NAME_LEN         5
 

> 
> Thanks for your time!
> 
> Regards,
> Anders
> 
> 
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-- 

Regards,
Heinz    -- The LVM Guy --

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

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Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen@Sistina.com                           +49 2626 141200
                                                       FAX 924446
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