Veritas Volume Manager (VxVM) - Online Resizing of Volumes

This post will help you with Veritas Volume Manager (VxVM) – Online Resizing of Volumes.

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Veritas Volume Manager (VxVM) – Online Resizing of Volumes

This article explains you how to resize the volumes online on Veritas Volume Manager (VxVM). In the previous post, We have covered,

Installation of Veritas Volume Manager (VxVM) on Linux
Veritas Volume Manager (VxVM) – Create Volume & Filesystem

Veritas Volume manager (VXVM) is very flexible and reliable volume manager to resize volumes without un-mounting it. Resizing the volumes are very common now and this has to done on fly without any downtime.

Topics involved:
1. How to find the total diskgroup size?
2. How to find maximum free size available in Diskgroup to extend or increase?
3. How to find the size of an existing volume upto how much it can grow?
4. How to increase or extend the Volume size?
5. How to resize the Volume size on fly means without unmounting the volume.

To achive this, we can use “vxassist” and “vxresize” commands to resizing the size of the volumes which means increase or reduce the size of volumes.

There are two parameters which can be used along with “vxassist” command to find the space available in a Diskgroup to know how much it can be increase or extend.

1. Maxsize – Use this option to find the size to which a new volume or existing volume can grow.
2. Maxgrow – Use this option to find the size to which an existing volume can be grown to.

1. How to find the total diskgroup size in Veritas Volume Manager?

#vxprint -g mytestdg -ug
TY NAME         ASSOC        KSTATE   LENGTH   PLOFFS   STATE    TUTIL0  PUTIL0
dg mytestdg     mytestdg     –        –        –        –        –       –
dm disk1        sdb          –        0.91g    –        –        –       –
v  testvol1     fsgen        ENABLED  0.48g    –        ACTIVE   –       –
pl testvol1-01  testvol1     ENABLED  0.48g    –        ACTIVE   –       –
sd disk1-01     testvol1-01  ENABLED  0.48g    0.00g    –        –       –

Above output shows that, mytestdg diskgroup is initiated with the disk “sdb” and the size of the disk is 0.91G. Volume “testvol1” size is 0.48G.

2. How to find maximum free size available in Diskgroup to extend or increase?

#vxassist -g mytestdg maxsize
Maximum volume size: 903168 (441Mb)

Where “mytestdg” is our Disk group name. Above Output shows that we have 441Mb of free volume size. This can be used to create a new volume or extending the existing volume.

3. How to find the size of an existing volume upto how much it can grow.

#vxassist -g mytestdg maxgrow testvol1
Volume testvol1 can be extended by 903168 to: 1927168 (941Mb)

Current size of the volume is 0.48G, we had found the size in the 1st point itself. So the volume can be increased to 941Mb.

There are multiple options available to resize a volumes using vxassist.
1. growto – to grow a volume to a specific volume size
2. growby – to grow a volume by a specific size
3. shrinkto – to shrink a volume to a specific size
4. shrinkby – to shrink a volume by a specific size

4. How to increase the Volume size in Veritas Volume Manager? or 
How to extend the Volume size in Veritas Volume Manager?

Option 1: To extend or increase the volumes to specific size 500mb, use growto option. so your total volume size would be 500mb.

#vxassist -g mytestdg growto testvol1 500M

Option 2: To extend or increase the volumes by specific size 800mb, use growby option. so your total volume size would be added with the specified size.

#vxassist -g mytestdg growby testvol1 800M

To resize the mounted volume size in veritas volume manager on fly without unmounting.

#vxresize -g mytestdg testvol1 1000M

5. How to decrease the Volume size in Veritas Volume Manager? or 
How to reduce the Volume size in Veritas Volume Manager?

Option 1: To reduce or decrease the volumes to specific size 500mb, use shrinkto option. so your total volume size would be 500mb.

#vxassist -g mytestdg shrinkto testvol1 500M

Option 2: To reduce or decrease the volumes by specific size 800mb, use shrinkby option. so your total volume size would be reduced the specified size from the total volume size.

#vxassist -g mytestdg shrinkby testvol1 800M

To resize the mounted volume size in veritas volume manager on fly without unmounting.

#vxresize -g mytestdg testvol1 800M

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