SUMMARY: Ufsdump Backup Problem on Mirrored Soft Partition on V48 0

From: Gilliam, Kirk R. <KGilliam_at_bcbsm.com>
Date: Fri May 23 2003 - 12:50:59 EDT
Here is the original message:

> Hello--
> 
> I have a Sunfire 480R running Solaris 8 2/02 (s28s_u7wos_08a),
> Generic_108528-18, with 4GB of ram and 2 - 900 MHz US-III+ CPU's and two
> SEAGATE 36.42GB mirrored disks with soft partitions and the OBP level is
> 4.6.4. The problem I am getting is my ufsdump backup fails for the slice
> "/dev/md/rdsk/d91" with the following errors and doing a metastat on "d91"
> reveals no errors. The 2 - 36GB disks are partitioned exactly alike. I
> have no "disk failure" messages anywhere on the system. I have ran a
> similar ufsdump on the two submirrors of the soft partition and I get the
> same results, so I have no way of figuring out if 1 disk is bad over the
> other or if somehow the soft partitioning is bad. Has anyone ever
> encountered this before? I have the identical configuration running on a
> Sunfire V120 (development server) with no problems.
> 
> Please see output below. I will summarize.
> 
> Thanks,
> 
> Kirk Gilliam
> Unix Systems Administrator
> Blue Cross Blue Shield of Michigan
> 
> 
> #######################################################################
> 	Backup Error
> #######################################################################
> 
> 030406.232416 : Backing up /dev/md/rdsk/d91
>   DUMP: Writing 63 Kilobyte records
>   DUMP: Date of this level 0 dump: Sun Apr 06 23:24:16 2003
>   DUMP: Date of last level 0 dump: the epoch
>   DUMP: Dumping /dev/md/rdsk/d91 (psx401a2370:/app/sunone/meta) to
> /dev/rmt/0n.
>   DUMP: Mapping (Pass I) [regular files]
>   DUMP: Mapping (Pass II) [directories]
>   DUMP: Estimated 817762 blocks (399.30MB).
>   DUMP: Dumping (Pass III) [directories]
>   DUMP: Dumping (Pass IV) [regular files]
>   DUMP: Warning - cannot read sector 6289353 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289354 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289355 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289356 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289357 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289358 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289359 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289392 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289393 of `/dev/md/rdsk/d91'
>   DUMP: Warning - cannot read sector 6289394 of `/dev/md/rdsk/d91'
> 			.
> 			.
> 			.
> DUMP: Warning - cannot read sector 6289455 of `/dev/md/rdsk/d91'
> DUMP: More than 32 block read errors from dump device `/dev/md/rdsk/d91'
> DUMP: NEEDS ATTENTION: Do you want to attempt to continue? ("yes" or "no")
> DUMP: The ENTIRE dump is
>  aborted.
> 030413.230342 : error during ufsdump
> 
> #############################################################
> 	Metastat Info
> #############################################################
> 
> d91: Mirror
>     Submirror 0: d71
>       State: Okay         
>     Submirror 1: d81
>       State: Okay         
>     Pass: 1
>     Read option: roundrobin (default)
>     Write option: parallel (default)
>     Size: 6289353 blocks
> 
> d71: Submirror of d91
>     State: Okay         
>     Size: 6289353 blocks
>     Stripe 0:
>         Devic Start Block  Dbase State        Hot Spare
>         d51          0     No    Okay         
> 
> d51: Soft Partition
>     Component: c1t0d0s6
>     State: Okay
>     Size: 6291456 blocks
>         Extent              Start Block              Block count
>              0                 20971522                  6291456
> 
> 
> d81: Submirror of d91
>     State: Okay         
>     Size: 6289353 blocks
>     Stripe 0:
>         Devic Start Block  Dbase State        Hot Spare
>         d61          0     No    Okay         
> 
> d61: Soft Partition
>     Component: c1t1d0s6
>     State: Okay
>     Size: 6291456 blocks
>         Extent              Start Block              Block count
>              0                 20971522                  6291456
> 
> #############################################################
> ******************** partition info *******************
> #############################################################
> 
> 0. c1t0d0 <SUN36G cyl 24620 alt 2 hd 27 sec 107>
> 
> Part      Tag    Flag     Cylinders         Size            Blocks
>   0       root    wm    2904 -  3629        1.00GB    (726/0/0)    2097414
>   1       swap    wu       0 -  2903        4.00GB    (2904/0/0)   8389656
>   2     backup    wm       0 - 24619       33.92GB    (24620/0/0) 71127180
>   3        usr    wm    3630 -  5081        2.00GB    (1452/0/0)   4194828
>   4        var    wm    5082 -  6533        2.00GB    (1452/0/0)   4194828
>   5       home    wm    6534 -  7985        2.00GB    (1452/0/0)   4194828
>   6 unassigned    wm    7986 - 24260       22.42GB    (16275/0/0) 47018475
>   7 unassigned    wm   24261 - 24619      506.42MB    (359/0/0)    1037151
> 
> 
> 1. c1t1d0 <SUN36G cyl 24620 alt 2 hd 27 sec 107>
> 
> Part      Tag    Flag     Cylinders         Size            Blocks
>   0       root    wm    2904 -  3629        1.00GB    (726/0/0)    2097414
>   1       swap    wu       0 -  2903        4.00GB    (2904/0/0)   8389656
>   2     backup    wm       0 - 24619       33.92GB    (24620/0/0) 71127180
>   3        usr    wm    3630 -  5081        2.00GB    (1452/0/0)   4194828
>   4        var    wm    5082 -  6533        2.00GB    (1452/0/0)   4194828
>   5       home    wm    6534 -  7985        2.00GB    (1452/0/0)   4194828
>   6 unassigned    wm    7986 - 24260       22.42GB    (16275/0/0) 47018475
>   7 unassigned    wm   24261 - 24619      506.42MB    (359/0/0)    1037151
----------------------------------------------------------------------------
----------------------------------------------------------------------------
--------------------------------------------------------
Thanks to Darren Dunham and Ed Skolnik for pointing me to the exact problem,
which was that the soft partition was larger than the mirrored meta device.

  The Real Credit goes to Bruce Perttunen ( my colleague here at Blue Cross
Blue Shield ). Some of Bruce's servers were getting the same ufsdump errors
as mine. A "Bug Track" is in the works with Sun Microsystems for this issue.
Bruce sums it up the best and here are his comments and the fix:

There is a possible file system level problem with soft partitions which are
mirrored.  Depending on how they were created, the filesystem could end up
being bigger than the metadevice it is sitting on.  The only problem this
has caused to this point is the failure of tape backups of the soft
partitions, however it is not known if other problems could arise so these
problems should be addressed quickly.

Mirrored Soft Partitions - Filesystem Problems

To determine if there is a problem

For each filesytem which is built on a mirrored soft partition, run the
metastat command (where d91 is the mirrored metadevice) to get the size of
the metadevice.

# metastat d91
d91: Mirror
    Submirror 0: d71
      State: Okay
    Submirror 1: d81
      State: Okay
    Pass: 1
    Read option: roundrobin (default)
    Write option: parallel (default)
    Size: 8386767 blocks

Now get the size of the filesystem by running the following command :

# fstyp -v /dev/md/rdsk/d91 | grep ncg
ncg     91      size    4194304 blocks  4128766

Double the value after the word "size" and compare it to size of the
mirrored metadevice. If the filesystem is bigger than the metadevice, the
filesystem must be rebuilt.

For example :

4194304 * 2 = 8388608

Since 8388608 is bigger than 8386767, there is a problem.


To fix the problem 

In order to fix the problem, the filesystem must rebuilt on the mirrored
metadevice.  To fix the example above, the following steps would be followed
:

1.	Shutdown all applications or processes using the filesystem
/dev/md/rdsk/d91
2.	Backup the filesystem /dev/md/rdsk/d91
3.	umount /dev/md/rdsk/d91
4.	newfs /dev/md/dsk/d91
5.	mount /dev/md/rdsk/d91
6.	Restore the data to the filesystem

If you have problems backing up d91, you may need to break the mirror and
backup either one of the sub-mirrors or one of the soft partitions.

What causes this problem

The problem seems to be caused if a filesystem is created on a soft
partition and then it is mirrored.  For example, the following would create
the problem...

1.	metainit d20 -p c1t0d0s7 1g
2.	newfs /dev/md/rdsk/d20
3.	metainit d30 1 1 d20
4.	metainit d40 -m d30

The correct way to do this would be...

1.	metainit d20 -p c1t0d0s7 1g
2.	metainit d30 1 1 d20
3.	metatinit d40 -m d30
4.	newfs /dev/md/rdsk/d40

Please keep in mind

If a server is using soft partitions which are not mirrored there is no
problem.  But if at a time later on these partitions need to be mirrored,
then the filesystem will need to be created on the mirror metadevice after
the mirror is set up.  

Kirk Gilliam
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Received on Fri May 23 12:50:52 2003

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