* Re: [linux-lvm] 0.9.1 vgscan doesn't detect upgraded vg's
2001-02-06 2:40 [linux-lvm] 0.9.1 vgscan doesn't detect upgraded vg's Michael McLinn
@ 2001-02-06 6:30 ` Andreas Dilger
2001-02-06 8:22 ` dmeyer
2001-02-07 9:44 ` Andreas Dilger
1 sibling, 1 reply; 5+ messages in thread
From: Andreas Dilger @ 2001-02-06 6:30 UTC (permalink / raw)
To: linux-lvm
Michael McLinn writes:
> I was running some large vg's with 0.8final, and upgraded
> to 0.9.1_beta3 w/ kernel 2.4.1-ac2.
>
> After the upgrade, vgscan does not find any volume groups.
>
> Reverting to prior tools + kernel does not work as the on disk
> vg structures have been altered (presumably upgraded to the v2
> format).
>
> I have no suitably recent vgcfg backups, so restoring is not an
> option.
>
> I look at the output of pvdata -U on a physical volume.
> I see 3 UUID slots, which matches the number of pv's in the vg.
> However, on the first pv in the vg, only the first one is filled.
> On the second pv in the vg, the first two are filled. On the
> third pv of the vg, all three are filled.
>
> Within pv_read_all_pv_of_vg.c, there is a call to
> pv_read_uuidlist(), this routine is scanning the first pv,
> and thus only returns one uuid.
>
> Later the result is only the first pv is returned from
> pv_read_all_pv_of_vg().
>
> My theory is each pv is supposed to have the the UUID's of
> itself, and all other pv's in it's vg within it's UUID
> datastructure. Is this so?
Correct. There was another user who reported the same bug, but after
they were playing with the system a bit, it started to work (i.e. the
UUIDs were filled in) so it was not looked at further.
> If this is the case, it seems it would be possible to write the
> correct UUID's to the datastructure on disk, and potentially
> improve (maybe even fix) my situation.
Yes, this is the case. To confirm that the UUIDs are causing the problem,
you can put printf() in pv_read_all_pv_of_vg() where it is checking
disks against UUIDs, whenever a disk is being discarded. If this is
really the problem, simply comment out this UUID check for now. It is
only an extra safety check for duplicate VG names or old PVs at this point.
This should allow you to load the VG again.
> One more note that might be of interest, these volume groups were
> created with a much earlier version of lvm, 0.6 or 0.7 I believe.
I don't know what the situation was with the other person who had
this same bug, but it is good to know anyways.
Cheers, Andreas
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [linux-lvm] 0.9.1 vgscan doesn't detect upgraded vg's
2001-02-06 2:40 [linux-lvm] 0.9.1 vgscan doesn't detect upgraded vg's Michael McLinn
2001-02-06 6:30 ` Andreas Dilger
@ 2001-02-07 9:44 ` Andreas Dilger
2001-02-07 11:40 ` Patrick Caulfield
1 sibling, 1 reply; 5+ messages in thread
From: Andreas Dilger @ 2001-02-07 9:44 UTC (permalink / raw)
To: linux-lvm
Michael McLinn writes:
> I look at the output of pvdata -U on a physical volume.
> I see 3 UUID slots, which matches the number of pv's in the vg.
> However, on the first pv in the vg, only the first one is filled.
> On the second pv in the vg, the first two are filled. On the
> third pv of the vg, all three are filled.
I've found the source of this bug. It is as follows, assuming an
old VG with no UUID information:
vg_write_with_pv_and_lv() is called to write VGDA to disk
for each PVs in the VG do
vg_write() - writes out VG data
pv_write_with_pe() - writes out PV data, creates new UUID if needed
pv_write_uuidlist() - writes out current UUID list
lv_write_all_lv() - writes out LV data
done
The problem is that UUIDs are being created as we go, so the UUID list
on the first PV only has the first PV UUID in it. Exactly the problem
you are having. I would think this problem would also show up with the
PV namelist as well, but maybe things were done slightly differently then.
It is probably that if you make more than one change which writes out the
VGDA, the problem is gone because the UUIDs now exist on all PVs.
The fix is to verify/fix the UUID list before we start writing PV info.
It appears that vg_write_with_pv_and_lv() is the only place that the UUID
list is written, via pv_write_uuidlist().
Unfortunately, this doesn't help anyone that currently has a problem, but
it will prevent such problems for anyone else upgrading their system.
Cheers, Andreas
========================================================================
diff -u -u -r1.1 pv_write_uuidlist.c
--- tools/lib/pv_write_uuidlist.c 2000/11/13 00:26:33 1.1
+++ tools/lib/pv_write_uuidlist.c 2001/02/07 09:00:08
@@ -30,6 +30,8 @@
*
* 08/02/2000 - use debug_enter()/debug_leave()
* 17/03/2000 - changed namelist to uuidlist
+ * 02/07/2001 - ensure we have valid UUIDs for all PVs before writing [AED]
+ * - use memcpy instead of strncpy for UUIDs
*
*/
@@ -37,7 +39,7 @@
int pv_write_uuidlist ( char *pv_name, vg_t *vg) {
- int p = 0, pp = 0;
+ int p = 0;
int pv_handle = -1;
int ret = 0;
int size = 0;
@@ -61,14 +63,23 @@
__FILE__, __LINE__);
ret = LVM_EPV_WRITE_UUIDLIST_MALLOC;
} else {
- memset ( pv_uuid_list, 0, size);
- for ( p = 0; p < vg->pv_max; p++) {
- if ( vg->pv[p] != NULL) {
- strncpy ( &pv_uuid_list[pp*NAME_LEN],
- vg->pv[p]->pv_uuid,
- UUID_LEN);
- pp++;
- }
+ char *u = memset(pv_uuid_list, 0, size);
+ for (p = 0; p < vg->pv_max; p++) {
+ pv_t *pv = vg->pv[p];
+ if (pv == NULL)
+ continue;
+
+ /* Create/fix UUIDs for any PVs that need it */
+ if (lvm_check_uuid(pv->pv_uuid) < 0) {
+#ifdef DEBUG
+ debug(__FUNCTION__ " -- creating new UUID for PV %s\n",
+ pv->pv_name);
+#endif
+ memset(pv->pv_uuid, 0, sizeof(pv->pv_uuid));
+ memcpy(pv->pv_uuid, lvm_create_uuid(UUID_LEN), UUID_LEN);
+ }
+ memcpy(u, pv->pv_uuid, UUID_LEN);
+ u += NAME_LEN;
}
if ( write ( pv_handle, pv_uuid_list, size) != size)
ret = -LVM_EPV_WRITE_UUIDLIST_WRITE;
diff -u -u -r1.2 vg_write_with_pv_and_lv.c
--- tools/lib/vg_write_with_pv_and_lv.c 2000/11/13 00:20:11 1.2
+++ tools/lib/vg_write_with_pv_and_lv.c 2001/02/07 09:00:21
@@ -55,9 +55,9 @@
vg->pv[p]->pv_name);
#endif
if ( ( ret = vg_write ( vg->pv[p]->pv_name, vg->pv[p], vg)) < 0) break;
+ if ( ( ret = pv_write_uuidlist ( vg->pv[p]->pv_name, vg)) < 0) break;
if ( ( ret = pv_write_with_pe ( vg->pv[p]->pv_name,
vg->pv[p])) < 0) break;
- if ( ( ret = pv_write_uuidlist ( vg->pv[p]->pv_name, vg)) < 0) break;
if ( ( ret = lv_write_all_lv ( vg->pv[p]->pv_name, vg)) < 0)
break;
}
--
Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert
^ permalink raw reply [flat|nested] 5+ messages in thread