Move data from pv to another one inside the same volume group

[RiclyLeRoy]

I have cluster HP-UX of 4 hosts with Service Guard and I need to move data of application to another physical disk. Application data is in /myapp/datafile (mount point) and this one is mounted to /dev/vg_myapp/lv_myapp_datafile.

mount point = /myapp/datafile
logical volume = /dev/vg_myapp/lv_myapp_datafile
volume group = /dev/vg_myapp
PV Name = /dev/disk/disk432

My target is :

1. to add new physical volume (e.g. /dev/disk/disk555) to volume group */dev/vg_myapp*

2. to move the existing data from /dev/disk/disk432 to /dev/disk/disk555

3. to remove old /dev/disk/disk432

In this way my app should have to see no changes because changes are applied to lower level that is volume group and physical device.
What do you think ? It's necessary to stop application to make this job ?

Can you suggest me what commands I need for these 3 points please?

[feigenL]

Hello there, please take a look at this thread, as it is quite complete on the steps of what seems you need to accomplish.

https://community.hpe.com/t5/operating-system-hp-ux/pvmove-is-online/td-p/6940919

regards.

[RiclyLeRoy]

@feigenL 

It's very interesting ! Thanks.

• # pvcreate /dev/rdisk/disknew ==> new disk
• # vgextend vgname /dev/disk/disknew
• # lvextend -L 74120 /dev/vgname/lvname ==> double the disk space of lvm
• # lvextend -m 1 /dev/vgname/lvname ==> mirror
• # lvreduce -m 0 /dev/vgname/lvname /dev/disk/diskold

I have some doubts...

1. About new disk which I'll have to create, It can be greater then source one ?
2. Mirror task is at logical volume level ?
3. Mirror task means every time it's necessary to write to disk, write operation is made on both volumes? Or It exist a primary disk and afterwards data copy is applied to second disk ?
4. if mirror is specified on logical volume according to this command " lvextend -m 1 <logical volume>",  It's natural to think disk to disk replication ?
5. It's necessary specific HP-UX license for mirror ?

[georgek_1 · Accepted solution]

RiclyLeRoy

I assume you have new disk already assigned to the server, and in CLAIMED state . 
The new disk needs to be same or larger size than disk432 to accommodate all data .
Add the new disk to /dev/vg_myapp, using vgextend command , # vgextend /dev/vg_myapp /dev/disk/disk555
At this stage , you may mirror the data, if you have MirrorDisk/UX software installed in server;
Using the command # lvextend -m 1 /dev/vg_myapp/lv_myapp_datafile /dev/disk/disk555 .
Please note that MirrorDisk/UX is a paid software , available with higher OE or purchased separately.
This can be checked with  # swlist -l bundle | grep -i mirror .

Once  the data is mirrored , you may reduce the lvol from OLD disk (disk432) using lvreduce .
# lvreduce -m 0 /dev/vg_myapp/lv_myapp_datafile /dev/disk/disk432

Remove the OLD disk - disk432 from /dev/vg_myapp, using # vgreduce /dev/vg_myapp /dev/disk/disk432 
You may check vg configuration (vgdisplay -v <vg_name> and data consistency, then un-presnt the OLD disk at this time .

Please make sure that you have data backup available before making any changes .
You could refer # man vgextend , # man lvextend , # man lvreduce and # man vgreduce for more information .

About new disk which I'll have to create, It can be greater than source one ?
Target disk has to be same or bigger than the source one.

Mirror task is at logical volume level ?
Yes We do mirror at the logical volume level.

Mirror task means every time it's necessary to write to disk, write operation is made on both volumes? Or It exist a primary disk and afterwards data copy is applied to second disk ?
Yes, writes to both volumes .

if mirror is specified on logical volume according to this command " lvextend -m 1 <logical volume>",  It's natural to think disk to disk replication ?
Usually , the policy of the lvol is set to "strict" by default ,  so that mirror copy would always go to next disk, will not be on same disk which is of no use . Else you may mention the target disk with lvextend command as shown above .

It's necessary specific HP-UX license for mirror ?
Yes , MirrorDisk/UX software is a licensed product .

I work for HPE/ I am an HPE Employee (HPE Community)