Veritas Volume Manager 5.0.1 Troubleshooting Guide, HP-UX 11i v3, First Edition, November 2009

Persistent FastResync uses a DCO volume to perform tracking of changed regions
in a volume. If an error occurs while reading or writing a DCO volume, it is detached
and the badlog flag is set on the DCO. All further writes to the volume are not
tracked by the DCO.
The following sample output from the vxprint command shows a complete volume
with a detached DCO volume (the TUTIL0 and PUTIL0 fields are omitted for clarity):
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE ...
dg mydg mydg - - - -
dm mydg01 c4t50d0 - 35521408 - -
dm mydg02 c4t51d0 - 35521408 - -
dm mydg03 c4t52d0 - 35521408 - FAILING
dm mydg04 c4t53d0 - 35521408 - FAILING
dm mydg05 c4t54d0 - 35521408 - -
v SNAP-vol1 fsgen ENABLED 204800 - ACTIVE
pl vol1-03 SNAP-vol1 ENABLED 204800 - ACTIVE
sd mydg05-01 vol1-03 ENABLED 204800 0 -
dc SNAP-vol1_dco SNAP-vol1 - - - -
v SNAP-vol1_dcl gen ENABLED 144 - ACTIVE
pl vol1_dcl-03 SNAP-vol1_dcl ENABLED 144 - ACTIVE
sd mydg05-02 vol1_dcl-03 ENABLED 144 0 -
sp vol1_snp SNAP-vol1 - - - -
v vol1 fsgen ENABLED 204800 - ACTIVE
pl vol1-01 vol1 ENABLED 204800 - ACTIVE
sd mydg01-01 vol1-01 ENABLED 204800 0 -
pl vol1-02 vol1 ENABLED 204800 - ACTIVE
sd mydg02-01 vol1-01 ENABLED 204800 0 -
dc vol1_dco vol1 - - - BADLOG
v vol1_dcl gen DETACHED 144 - DETACH
pl vol1_dcl-01 vol1_dcl ENABLED 144 - ACTIVE
sd mydg03-01 vol1_dcl-01 ENABLED 144 0 -
pl vol1_dcl-02 vol1_dcl DETACHED 144 - IOFAIL
sd mydg04-01 vol1_dcl-02 ENABLED 144 0 RELOCATE
sp SNAP-vol1_snp vol1 - - - -
This output shows the mirrored volume, vol1, its snapshot volume, SNAP-vol1,
and their respective DCOs, vol1_dco and SNAP-vol1_dco. The two disks, mydg03
and mydg04, that hold the DCO plexes for the DCO volume, vol1_dcl, of vol1 have
failed. As a result, the DCO volume, vol1_dcl, of the volume, vol1, has been
detached and the state of vol1_dco has been set to BADLOG. For future reference,
29Recovering from hardware failure
Recovery from failure of a DCO volume