Mirror operations with VxVM and LVM
In today post I will show how to create and brake a mirrored volume in Veritas Volume Manager and Logical Volume Manager.
LVM
Creating a mirror of a volume and later split it in LVM is quite easy an can be done with a few commands. I’m going to suppose that the original volume is already created.
- Extend the Volume Group that contain the
lvol
It has to be done with the same number of disks and of the same size that the ones within the VG.
[root@sheldon] / # vgextend vg_oracle /dev/disk/disk26
Volume group "vg_oracle" has been successfully extended.
Volume Group configuration for /dev/vg_oracle has been saved in /etc/lvmconf/vg_oracle.conf
[root@sheldon] / #
- Create the mirror
[root@sheldon] / # lvextend -m 1 /dev/vg_oracle/lv_oracle /dev/disk/disk26
The newly allocated mirrors are now being synchronized. This operation will
take some time. Please wait ....
Logical volume "/dev/vg_oracle/lv_oracle" has been successfully extended.
Volume Group configuration for /dev/vg_oracle has been saved in /etc/lvmconf/vg_oracle.conf
[root@sheldon] / #
- Check the configuration
[root@sheldon] / # lvdisplay /dev/vg_oracle/lv_oracle
--- Logical volumes ---
LV Name /dev/vg_oracle/lv_oracle
VG Name /dev/vg_oracle
LV Permission read/write
LV Status available/syncd
Mirror copies 1
Consistency Recovery MWC
Schedule parallel
LV Size (Mbytes) 208
Current LE 13
Allocated PE 26
Stripes 0
Stripe Size (Kbytes) 0
Bad block NONE
Allocation strict
IO Timeout (Seconds) default
Number of Snapshots 0
[root@sheldon] / #
- Perform the split
[root@sheldon] / # lvsplit -s copy /dev/vg_oracle/lv_oracle
Logical volume "/dev/vg_oracle/lv_oraclecopy" has been successfully created with
character device "/dev/vg_oracle/rlv_oraclecopy".
Logical volume "/dev/vg_oracle/lv_oracle" has been successfully split.
Volume Group configuration for /dev/vg_oracle has been saved in /etc/lvmconf/vg_oracle.conf
[root@sheldon] / #
- Reestablish the mirror
If the VG are 1.0 or 2.0 version the merge can not be performed if the group is in shared mode, for the 2.1 volume groups the lvmerge can be done in any mode.
The order to do the merge is the copy FIRST and the master SECOND. This is very important if don’t want to sync the mirror in wrong direction.
[root@sheldon] / # lvmerge /dev/vg_oracle/lv_oraclecopy /dev/vg_oracle/lv_oracle
Logical volume "/dev/vg_oracle/lv_oraclecopy" has been successfully merged
with logical volume "/dev/vg_oracle/lv_oracle".
Logical volume "/dev/vg_oracle/lv_oraclecopy" has been successfully removed.
Volume Group configuration for /dev/vg_oracle has been saved in /etc/lvmconf/vg_oracle.conf
[root@sheldon] / #
VXVM
The process in VxVM is in many ways similar to the LVM one.
- Add a new disk/disks to the
diskgroup
Launch vxdiskadm tool and select Add or initialize one or more disks.
[root@sheldon] / # vxdiskadm
Volume Manager Support Operations
Menu: VolumeManager/Disk
1 Add or initialize one or more disks
2 Remove a disk
3 Remove a disk for replacement
4 Replace a failed or removed disk
5 Mirror volumes on a disk
6 Move volumes from a disk
7 Enable access to (import) a disk group
8 Remove access to (deport) a disk group
9 Enable (online) a disk device
10 Disable (offline) a disk device
11 Mark a disk as a spare for a disk group
12 Turn off the spare flag on a disk
13 Remove (deport) and destroy a disk group
14 Unrelocate subdisks back to a disk
15 Exclude a disk from hot-relocation use
16 Make a disk available for hot-relocation use
17 Prevent multipathing/Suppress devices from VxVM's view
18 Allow multipathing/Unsuppress devices from VxVM's view
19 List currently suppressed/non-multipathed devices
20 Change the disk naming scheme
21 Change/Display the default disk layouts
22 Mark a disk as allocator-reserved for a disk group
23 Turn off the allocator-reserved flag on a disk
list List disk information
? Display help about menu
?? Display help about the menuing system
q Exit from menus
Select an operation to perform: 1
Enter the disk and answer the questions according to your configuration and exit the tool when the process is done.
Add or initialize disks
Menu: VolumeManager/Disk/AddDisks
Use this operation to add one or more disks to a disk group. You can
add the selected disks to an existing disk group or to a new disk group
that will be created as a part of the operation. The selected disks may
also be added to a disk group as spares. Or they may be added as
nohotuses to be excluded from hot-relocation use. The selected
disks may also be initialized without adding them to a disk group
leaving the disks available for use as replacement disks.
More than one disk or pattern may be entered at the prompt. Here are
some disk selection examples:
all: all disks
c3 c4t2: all disks on both controller 3 and controller 4, target 2
c3t4d2: a single disk (in the c#t#d# naming scheme)
xyz_0: a single disk (in the enclosure based naming scheme)
xyz_: all disks on the enclosure whose name is xyz
disk#: a single disk (in the new naming scheme)
Select disk devices to add: [<pattern-list>,all,list,q,?] disk28
Here is the disk selected. Output format: [Device_Name]
disk28
Continue operation? [y,n,q,?] (default: y)
You can choose to add this disk to an existing disk group, a
new disk group, or leave the disk available for use by future
add or replacement operations. To create a new disk group,
select a disk group name that does not yet exist. To leave
the disk available for future use, specify a disk group name
of "none".
Which disk group [<group>,none,list,q,?] (default: none) dg_sap
Use a default disk name for the disk? [y,n,q,?] (default: y) n
Add disk as a spare disk for dg_sap? [y,n,q,?] (default: n)
Exclude disk from hot-relocation use? [y,n,q,?] (default: n)
Add site tag to disk? [y,n,q,?] (default: n)
The selected disks will be added to the disk group dg_sap with
disk names that you will specify interactively.
disk28
Continue with operation? [y,n,q,?] (default: y)
Initializing device disk28.
Enter desired private region length
[<privlen>,q,?] (default: 32768)
Enter disk name for disk28 [<name>,q,?] (default: dg_sap02)
VxVM NOTICE V-5-2-88
Adding disk device disk28 to disk group dg_sap with disk
name dg_sap02.
Add or initialize other disks? [y,n,q,?] (default: n)
- Check the configuration.
[root@sheldon] / # vxprint -g dg_sap
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE TUTIL0 PUTIL0
dg dg_sap dg_sap - - - - - -
dm dg_sap01 disk27 - 228224 - - - -
dm dg_sap02 disk28 - 228224 - - - -
v sapvol fsgen ENABLED 204800 - ACTIVE - -
pl sapvol-01 sapvol ENABLED 204800 - ACTIVE - -
sd dg_sap01-01 sapvol-01 ENABLED 204800 0 - - -
[root@sheldon] / #
- Create the mirror.
[root@sheldon] / # vxassist -g dg_sap mirror sapvol dg_sap02
[root@sheldon] / #
[root@sheldon] / # vxprint -g dg_sap
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE TUTIL0 PUTIL0
dg dg_sap dg_sap - - - - - -
dm dg_sap01 disk27 - 228224 - - - -
dm dg_sap02 disk28 - 228224 - - - -
v sapvol fsgen ENABLED 204800 - ACTIVE - -
pl sapvol-01 sapvol ENABLED 204800 - ACTIVE - -
sd dg_sap01-01 sapvol-01 ENABLED 204800 0 - - -
pl sapvol-02 sapvol ENABLED 204800 - ACTIVE - -
sd dg_sap02-01 sapvol-02 ENABLED 204800 0 - - -
[root@sheldon] / #
- Break the mirror.
To do this just disassociate the corresponding plex from the volume.
[root@sheldon] / # vxplex -g dg_sap dis sapvol-02
[root@sheldon] / # vxprint -g dg_sap
TY NAME ASSOC KSTATE LENGTH PLOFFS STATE TUTIL0 PUTIL0
dg dg_sap dg_sap - - - - - -
dm dg_sap01 disk27 - 228224 - - - -
dm dg_sap02 disk28 - 228224 - - - -
pl sapvol-02 - DISABLED 204800 - - - -
sd dg_sap02-01 sapvol-02 ENABLED 204800 0 - - -
v sapvol fsgen ENABLED 204800 - ACTIVE - -
pl sapvol-01 sapvol ENABLED 204800 - ACTIVE - -
sd dg_sap01-01 sapvol-01 ENABLED 204800 0 - - -
[root@sheldon] / #
- Reattach the
plexto the volume and reestablish the mirror.
[root@sheldon] / # vxplex -g dg_sap att sapvol sapvol-02
And we are done for now, more VxVM stuff in a future post.
Juanma.
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