On Tuesday August 5, davidchow@shaolinmicro.com wrote:
> >
> >
> >Rather than a hex dump, just use
> >
> > mdadm --examine /dev/XXX
> >
> >That is the easiest way to view the superblock on the device.
> >
> >NeilBrown
> >
> Neil,
>
> OK, I find out there is a problem in the superblock which is descrbed as
> follows. The "Total Devices" is wrong. It should be 2 instead of 3. This
> is probably a bug of the mkraid (from raidtools) which when I created
> the array with a "failed-disk" in degraded mode. mkraid incorrectly made
> a wrong superblock even I put "nr-raid-disk 2" and "nr-spare-disks 0" in
> the raidtab. Ok, the superblock is incorrect, but how can I change the
> total devices and spare device pramaters without re-initialize the
> array?
It is actuallt "Active Devices" that is the problem. As this is the
same as "Raid Devices", it doesn't bother doing a reconstruction.
The following patch adds --update=summaries to mdadm-1.3.0, which
updates the various summary fields in the superblock (Total, Active,
Working, Failed, Spare - Devices).
It is untested but should work.
If you patch mdadm-1.3.0 and compile it, then
mdadm --assemble /dev/md2 --update=summaries /dev/sda3 /dev/sdb3
then it should update these fields and start the array (you might need
a --run as well).
Let me know how it goes.
NeilBrown
----------- Diffstat output ------------
./Assemble.c | 25 +++++++++++++++++++++++++
./ReadMe.c | 4 ++--
./mdadm.c | 4 +++-
3 files changed, 30 insertions(+), 3 deletions(-)
diff ./Assemble.c~current~ ./Assemble.c
--- ./Assemble.c~current~ 2003-08-05 16:40:07.000000000 +1000
+++ ./Assemble.c 2003-08-05 16:49:00.000000000 +1000
@@ -292,6 +292,31 @@ int Assemble(char *mddev, int mdfd,
fprintf(stderr, Name ": updating superblock of %s with minor number %d\n",
devname, super.md_minor);
}
+ if (strcmp(update, "summaries") == 0) {
+ /* set nr_disks, active_disks, working_disks,
+ * failed_disks, spare_disks based on disks[]
+ * array in superblock
+ */
+ super.nr_disks = super.active_disks =
+ super.working_disks = super.failed_disks =
+ super.spare_disks = 0;
+ for (i=0; MD_SB_DISKS ; i++)
+ if (super.disks[i].major ||
+ super.disks[i].minor) {
+ int state = super.disks[i].state;
+ if (state & (1<<MD_DISK_REMOVED))
+ continue;
+ super.nr_disks++;
+ if (state & (1<<MD_DISK_ACTIVE))
+ super.active_disks++;
+ if (state & (1<<MD_DISK_FAULTY))
+ super.failed_disks++;
+ else
+ super.working_disks++;
+ if (state == 0)
+ super.spare_disks++;
+ }
+ }
super.sb_csum = calc_sb_csum(&super);
dfd = open(devname, O_RDWR, 0);
if (dfd < 0)
diff ./ReadMe.c~current~ ./ReadMe.c
--- ./ReadMe.c~current~ 2003-08-05 16:38:03.000000000 +1000
+++ ./ReadMe.c 2003-08-05 16:38:35.000000000 +1000
@@ -221,7 +221,7 @@ char OptionHelp[] =
" --config= -c : config file\n"
" --scan -s : scan config file for missing information\n"
" --force -f : Assemble the array even if some superblocks appear out-of-date\n"
-" --update= -U : Update superblock: either sparc2.2 or super-minor\n"
+" --update= -U : Update superblock: one of sparc2.2, super-minor or summaries\n"
"\n"
" For detail or examine:\n"
" --brief -b : Just print device name and UUID\n"
@@ -344,7 +344,7 @@ char Help_assemble[] =
" for a full array are present\n"
" --force -f : Assemble the array even if some superblocks appear\n"
" : out-of-date. This involves modifying the superblocks.\n"
-" --update= -U : Update superblock: either sparc2.2 or super-minor\n"
+" --update= -U : Update superblock: one of sparc2.2, super-minor or summaries\n"
;
char Help_manage[] =
diff ./mdadm.c~current~ ./mdadm.c
--- ./mdadm.c~current~ 2003-08-05 16:39:52.000000000 +1000
+++ ./mdadm.c 2003-08-05 16:52:37.000000000 +1000
@@ -397,7 +397,9 @@ int main(int argc, char *argv[])
if (strcmp(update, "sparc2.2")==0) continue;
if (strcmp(update, "super-minor") == 0)
continue;
- fprintf(stderr, Name ": '--update %s' invalid. Only 'sparc2.2' or 'super-minor' supported\n",update);
+ if (strcmp(update, "summaries")==0)
+ continue;
+ fprintf(stderr, Name ": '--update %s' invalid. Only 'sparc2.2', 'super-minor' or 'summaries' supported\n",update);
exit(2);
case O(ASSEMBLE,'c'): /* config file */
-
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