Recovering a Corrupt Root AdvFS Domain

From: Adrian Morin <amorin_at_dbtech.com.au>
Date: Thu, 15 Apr 1999 02:39:45 +0800

Hello All

This is a follow on from the bfs_access Panic problem I encountered.

The Following is the output from the verify of the root_domain.

+++ Domain verification +++

Domain Id 35eb339b.0009fa51

Checking disks ...

Checking storage allocated on disk /dev/re0a

Checking mcell list ...

Checking mcell position field ...

Checking tag directories ...
check_tagdir_page: in-use on-disk tag does not have matching in-mem tag hdr
    set tag: 1.32769 (0x00000001.0x00008001)
    tag: 1650.36959 (0x00000672.0x0000905f)
    tag directory page: 1
    tag map entry: 628
    seqNo: 0x905f (36959)
    vdIndex: 1
    bfMCId (page.cell): 115.24
check_tagdir_page: bad allocated tag count
    set tag: -2.0 (0xfffffffe.0x00000000)
    tag: 1.32769 (0x00000001.0x00008001)
    tag directory page: 1
    real count: 639, expected count: 632
check_tagdir_page: bad free tag count
    set tag: -2.0 (0xfffffffe.0x00000000)
    tag: 1.32769 (0x00000001.0x00008001)
    tag directory page: 1
    real count: 383, expected count: 390
check_one_tagdir: bad free tag count
    set tag: -2.0 (0xfffffffe.0x00000000)
    tag: 1.32769 (0x00000001.0x00008001)
    real count: 383, expected count: 390

+++ Fileset verification +++

+++ Fileset / +++

Checking frag file headers ...

Checking frag file type lists ...

Scanning directories and files ...
    1700
Scanning tags ...
    1600
Searching for lost files ...
    1600

----------------------------------------------------------------------------

----
After researching this problem I have found some messages that indicate this
is possibly normal for a root domain. However all other domains show no
problems when I run verify. Therefore I am asuming that in my case this is a
problem that I need to resolve.
Would this be a fair assumption?
When I run a verify -r -f root_domain it lists the same as the verify -r.
Therefore verify does not fix this problem. From what I have read and been
told this leaves me with no other option but to vdump the root filesystem,
remove the root_domain, recreate the root_domain and restore the root
filesystem.
Does that sound right?
That being the case I am a bit unsure exactly how to do this. I have found
some details on how to do this with a substitute disk. However all our disks
are in use and I would prefer to not have to remove any further data to free
up disks to carry this out.
This leaves me with two further questions.
1. Am I best to clear out a disk so that I can dump root to another disk
then boot of the other new copy of root and then recreate the root partition
where it was in the first place?
or
2. Is it possible to boot from cd and drop and recreate the root domain
without loosing any other data?
What should I whatch out for with either approach?
Any ideas greatly appreciated.
Cheers
Adrian Morin
_____________________________________________________________
Adrian Morin
Principal Consultant, Applications Technical Services
Database Technology PTY LTD
 
Tel:  (08) 9481 0778
Fax:  (08) 9481 0779
Mob:  0417 937 230
 
Email: mailto:amorin_at_dbtech.com.au
Web:   http://www.dbtech.com.au/
_____________________________________________________________
 

Received on Wed Apr 14 1999 - 21:11:37 NZST