Creating and Managing a Linked Snapshot in Storage Foundation
This is a practical example on how to create and manage a linked snapshot in Storage Foundation.
Initial situation:
Source dg: dg_src (with dco)
root@ / #vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl
v src_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl src_vol_dcl-01 src_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_src-02 src_vol_dcl-01 lun_src 20971520 1712 0 xp12k0_11 ENA
Source fs: /mnt/sorce_fs
root@#df -g /mnt/sorce_fs
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/vx/dsk/dg_src/src_vol 10.00 9.36 7% 4 1% /mnt/sorce_fs
DG/volume for linked snap dg: dg_ln_snap (whit dco)
root@ / #vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl
v ln_snap_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl ln_snap_vol_dcl-01 ln_snap_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_ln_snap-02 ln_snap_vol_dcl-01 lun_ln_snap 20971520 1712 0 xp12k0_10 ENA
Create the linked snapshot:
root@ #vxsnap -g dg_src -b addmir src_vol mirvol=ln_snap_vol mirdg=dg_ln_snap
root@ / #vxtask -l list
Task: 1072 RUNNING
Type: LINKSYNC
Operation: LINKSYNC Vol ln_snap_vol Dg dg_ln_snap
Started: Mon Mar 30 13:08:10 DFT 2009
Throttle: 0
Progress: 3.33% 698368 of 20971520 Blocks
Work time: 4 seconds (01:56 remaining)
Prints of dgs:
Source:
root@ #vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl
v src_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl src_vol_dcl-01 src_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_src-02 src_vol_dcl-01 lun_src 20971520 1712 0 xp12k0_11 ENA
ln src_vol_ln src_vol src_vol_dco
Snapshot:
root@/ #vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl
v ln_snap_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl ln_snap_vol_dcl-01 ln_snap_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_ln_snap-02 ln_snap_vol_dcl-01 lun_ln_snap 20971520 1712 0 xp12k0_10 ENA
ln ln_snap_vol_ln ln_snap_vol ln_snap_vol_dco
Make of the snapshot volume
vxsnap -g dg_src make source=src_vol/snapvol=ln_snap_vol/snapdg=dg_ln_snap
NB the ln object becamed a sp object
Print source dg/vol:
root@#vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl
v src_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl src_vol_dcl-01 src_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_src-02 src_vol_dcl-01 lun_src 20971520 1712 0 xp12k0_11 ENA
sp ln_snap_vol_snp src_vol src_vol_dco
Print snapshot dg/vol:
root@t #vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl
v ln_snap_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl ln_snap_vol_dcl-01 ln_snap_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_ln_snap-02 ln_snap_vol_dcl-01 lun_ln_snap 20971520 1712 0 xp12k0_10 ENA
sp src_vol_snp ln_snap_vol ln_snap_vol_dco
Now you can fsck and mount the snapshot volume:
root@ #fsck -V vxfs /dev/vx/dsk/dg_ln_snap/ln_snap_vol
file system is clean - log replay is not required
root@ #mount -V vxfs /dev/vx/dsk/dg_ln_snap/ln_snap_vol /mnt/ln_snap
Reattach the snapshot volume (umount it before proceeding)
root@ #vxsnap -g dg_ln_snap reattach ln_snap_vol source=src_vol sourcedg=dg_src
NB the object sp has again become an ln object
Print of source dg/volume
root@ #vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl
v ln_snap_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl ln_snap_vol_dcl-01 ln_snap_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_ln_snap-02 ln_snap_vol_dcl-01 lun_ln_snap 20971520 1712 0 xp12k0_10 ENA
ln ln_snap_vol_ln ln_snap_vol ln_snap_vol_dco
Print of snapshot dg/volume
root@#vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl
v src_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl src_vol_dcl-01 src_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_src-02 src_vol_dcl-01 lun_src 20971520 1712 0 xp12k0_11 ENA
ln src_vol_ln src_vol src_vol_dco
To check if the reattach is ended:
root@ #vxsnap -g dg_src snapwait src_vol mirvol=ln_snap_vol mirdg=dg_ln_snap
Snapshot ready on volume src_vol
RESIZE of LINKED SNAPSHOT
If you perform a resize of the source volume when the snapshot is linked the snapshot volume get resized too:
Print of source dg/vol:
root@ #vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl
v src_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl src_vol_dcl-01 src_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_src-02 src_vol_dcl-01 lun_src 20971520 1712 0 xp12k0_11 ENA
ln src_vol_ln src_vol src_vol_dco
Print of snapshot dg/vol:
root@ #vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 20971520 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 20971520 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl
v ln_snap_vol_dcl - ENABLED ACTIVE 1712 SELECT - gen
pl ln_snap_vol_dcl-01 ln_snap_vol_dcl ENABLED ACTIVE 1712 CONCAT - RW
sd lun_ln_snap-02 ln_snap_vol_dcl-01 lun_ln_snap 20971520 1712 0 xp12k0_10 ENA
ln ln_snap_vol_ln ln_snap_vol ln_snap_vol_dco
Resize of source volume:
root@#vxresize -g dg_src src_vol +2G
Task of ln sync volumes:
root@ #vxtask -l list
Task: 1084 RUNNING
Type: LINKSYNC
Operation: LINKSYNC Vol ln_snap_vol Dg dg_ln_snap
Started: Mon Mar 30 14:57:57 DFT 2009
Throttle: 0
Progress: 7.57% 1905152 of 25165824 Blocks
Work time: 18 seconds (03:39 remaining)
After resize:
Print of sorce volume:
root@#vxprint -Qqthg dg_src
dg dg_src default default 6000 1238408559.174.tx088sd1
dm lun_src xp12k0_11 auto 65536 204713728 -
v src_vol - ENABLED ACTIVE 25165824 SELECT - fsgen
pl src_vol-01 src_vol ENABLED ACTIVE 25165824 CONCAT - RW
sd lun_src-01 src_vol-01 lun_src 0 20971520 0 xp12k0_11 ENA
sd lun_src-04 src_vol-01 lun_src 20975504 4194304 20971520 xp12k0_11 ENA
dc src_vol_dco src_vol src_vol_dcl1
v src_vol_dcl1 - ENABLED ACTIVE 2272 SELECT - gen
pl src_vol_dcl1-01 src_vol_dcl1 ENABLED ACTIVE 2272 CONCAT - RW
sd lun_src-03 src_vol_dcl1-01 lun_src 20973232 2272 0 xp12k0_11 ENA
ln src_vol_ln src_vol src_vol_dco
New size of fs:
root@#df -g /dev/vx/dsk/dg_src/src_vol
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/vx/dsk/dg_src/src_vol 12.00 7.92 35% 10 1% /mnt/sorce_fs
Print of Snapshot dg/vol (got automagically resized):
root@#vxprint -Qqthg dg_ln_snap
dg dg_ln_snap default default 15000 1238408593.178.tx088sd1
dm lun_ln_snap xp12k0_10 auto 65536 204713728 -
v ln_snap_vol - ENABLED ACTIVE 25165824 SELECT - fsgen
pl ln_snap_vol-01 ln_snap_vol ENABLED ACTIVE 25165824 CONCAT - RW
sd lun_ln_snap-01 ln_snap_vol-01 lun_ln_snap 0 20971520 0 xp12k0_10 ENA
sd lun_ln_snap-04 ln_snap_vol-01 lun_ln_snap 20975504 4194304 20971520 xp12k0_10 ENA
dc ln_snap_vol_dco ln_snap_vol ln_snap_vol_dcl1
v ln_snap_vol_dcl1 - ENABLED ACTIVE 2272 SELECT - gen
pl ln_snap_vol_dcl1-01 ln_snap_vol_dcl1 ENABLED ACTIVE 2272 CONCAT - RW
sd lun_ln_snap-03 ln_snap_vol_dcl1-01 lun_ln_snap 20973232 2272 0 xp12k0_10 ENA
ln ln_snap_vol_ln ln_snap_vol ln_snap_vol_dco
Cheers
Marco
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