How to Create a VxVM Snapshot from a mirror volume

VxVM 的 Volume Instance Snapshot 功能
Require: Storage Foundation Enterprise Version

有三種方式：
* Third-mirror break-off snapshots
* Full-sized snapshots
* Space-optimized snapshots

這兒介紹的就是第一種，範例如下

# vxrpint -th -g dg1

dg dg1          default      default  27000    1253797071.15.t2000

dm dg101        c1t2d0s2     auto     65536    143283520 -
dm dg103        c1t3d0s2     auto     65536    143283520 -

v  oracle_vol   -            ENABLED  ACTIVE   83886080 SELECT    -        fsgen
pl oracle_vol-01 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg101-03     oracle_vol-01 dg101   41943040 83886080 0         c1t2d0   ENA
pl oracle_vol-02 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg103-01     oracle_vol-02 dg103   0        83886080 0         c1t3d0   ENA

1. enable FastResync
# vxsnap -g dg1 prepare oracle_vol ndcomirs=1 alloc=dg101

# vxprint -th -g dg1

v  oracle_vol   -            ENABLED  ACTIVE   83886080 SELECT    -        fsgen
pl oracle_vol-01 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg101-03     oracle_vol-01 dg101   41943040 83886080 0         c1t2d0   ENA
pl oracle_vol-02 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg103-01     oracle_vol-02 dg103   0        83886080 0         c1t3d0   ENA
dc oracle_vol_dco oracle_vol oracle_vol_dcl
v  oracle_vol_dcl -          ENABLED  ACTIVE   6304     SELECT    -        gen
pl oracle_vol_dcl-01 oracle_vol_dcl ENABLED ACTIVE 6304 CONCAT    -        RW
sd dg101-01     oracle_vol_dcl-01 dg101 125829120 6304  0         c1t2d0   ENA

2. create a break-off snapshot volume
# vxsnap -g dg1 make source=oracle_vol/newvol=SNAP-oracle_vol/plex=oracle_vol-02

# vxprint -th g dg1

v  SNAP-oracle_vol -         ENABLED  ACTIVE   83886080 ROUND     -        fsgen
pl oracle_vol-02 SNAP-oracle_vol ENABLED ACTIVE 83886080 CONCAT   -        RW
sd dg103-01     oracle_vol-02 dg103   0        83886080 0         c1t3d0   ENA
dc SNAP-oracle_vol_dco SNAP-oracle_vol SNAP-oracle_vol_dcl
v  SNAP-oracle_vol_dcl -     ENABLED  ACTIVE   6304     SELECT    -        gen
pl SNAP-oracle_vol_dcl-01 SNAP-oracle_vol_dcl ENABLED ACTIVE 6304 CONCAT - RW
sd dg103-02     SNAP-oracle_vol_dcl-01 dg103 83886080 6304 0      c1t3d0   ENA
sp oracle_vol_snp SNAP-oracle_vol SNAP-oracle_vol_dco

v  oracle_vol   -            ENABLED  ACTIVE   83886080 SELECT    -        fsgen
pl oracle_vol-01 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg101-03     oracle_vol-01 dg101   41943040 83886080 0         c1t2d0   ENA
dc oracle_vol_dco oracle_vol oracle_vol_dcl
v  oracle_vol_dcl -          ENABLED  ACTIVE   6304     SELECT    -        gen
pl oracle_vol_dcl-01 oracle_vol_dcl ENABLED ACTIVE 6304 CONCAT    -        RW
sd dg101-01     oracle_vol_dcl-01 dg101 125829120 6304  0         c1t2d0   ENA
sp SNAP-oracle_vol_snp oracle_vol oracle_vol_dco

3. check snapshot status
# vxsnap -g dg1 -xv list

NAME          DG         OBJTYPE SNAPTYPE PARENT     PARENTDG   SNAPDATE         CHANGED_DATA SYNCED_DATA
oracle_vol    dg1        vol     -        -          -          - -              - -          40G (100%)
SNAP-oracle_vol dg1      vol     fullinst oracle_vol dg1        2011/07/31 02:57 64K (0.0%)   40G (100%)

4. split dg
# vxdg split dg1 dg2 SNAP-oracle_vol

# vxprint -th

dg dg1          default      default  27000    1253797071.15.t2000
dm dg101        c1t2d0s2     auto     65536    143283520 -

v  oracle_vol   -            ENABLED  ACTIVE   83886080 SELECT    -        fsgen
pl oracle_vol-01 oracle_vol  ENABLED  ACTIVE   83886080 CONCAT    -        RW
sd dg101-03     oracle_vol-01 dg101   41943040 83886080 0         c1t2d0   ENA
dc oracle_vol_dco oracle_vol oracle_vol_dcl
v  oracle_vol_dcl -          ENABLED  ACTIVE   6304     SELECT    -        gen
pl oracle_vol_dcl-01 oracle_vol_dcl ENABLED ACTIVE 6304 CONCAT    -        RW
sd dg101-01     oracle_vol_dcl-01 dg101 125829120 6304  0         c1t2d0   ENA
sp SNAP-oracle_vol_snp oracle_vol oracle_vol_dco

dg dg2          default      default  7000     1312053225.56.t2000
dm dg103        c1t3d0s2     auto     65536    143283520 -

v  SNAP-oracle_vol -         ENABLED  ACTIVE   83886080 ROUND     -        fsgen
pl oracle_vol-02 SNAP-oracle_vol ENABLED ACTIVE 83886080 CONCAT   -        RW
sd dg103-01     oracle_vol-02 dg103   0        83886080 0         c1t3d0   ENA
dc SNAP-oracle_vol_dco SNAP-oracle_vol SNAP-oracle_vol_dcl
v  SNAP-oracle_vol_dcl -     ENABLED  ACTIVE   6304     SELECT    -        gen
pl SNAP-oracle_vol_dcl-01 SNAP-oracle_vol_dcl ENABLED ACTIVE 6304 CONCAT - RW
sd dg103-02     SNAP-oracle_vol_dcl-01 dg103 83886080 6304 0      c1t3d0   ENA
sp oracle_vol_snp SNAP-oracle_vol SNAP-oracle_vol_dco

5. join dg (snap vol refresh reattach must in the same dg)
# vxdg join dg2 dg1

6. Refresh snapshot (source vol, snapshit vol must in the same dg)
# vxsnap -g dg1 refresh SNAP-oracle_vol

7. Reattach, (source vol, snapshit vol must in the same dg)
# vxsnap -b -g dg1 reattach SNAP-oracle_vol source=oracle_vol

.