How To Mirror VG and Root VG

How To Mirror VG and Root VG

There are steps involved through which administrator can mirror a VG and RootVg.

Steps tp mirror a VG:

Step 1: Extend the VG.

# extendvg <vgname> <pvname>

Step 2: mirror the VG.

# mirrorvg <vgname> <pvname>

Step 3: synchronize the VG.

# syncvg <vgname>

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Steps to mirror RootVg:

There are steps by which admin can mirror a root vg:

Step 1: extend rootvg to a new pv:

# extendvg rootvg <pvname>

For eg:

# extendvg rootvg hdisk6

Step 2: mirror rootvg

# mirrorvg –m rootvg hdisk6

Step 3: make it bootable:

# bosboot –ad /dev/hdisk6

Step 4: define boot order:

# bootlist –m normal hdisk4 hdisk6

Step 5: synchronize rootvg:

# syncvg rootvg

Reboot OS to disable quorum checking on rootvg (By default disabled, when rootvg is mirrored but reboot is required).

Why rootvg is mirrored?

The main reason to mirror rootvg is to protect OS from disk failure.

Happy Learning !

VG Commands

Although we have already discussed the use of VG Commands in detail in previous posts on LVM, this post will give a brief review about the various VG commands we have learned so far.

# mkvg

Command is used to create a new VG.

# extendvg

Command is used to add PVs to VG.

# reducevg

Command is used to remove PV from VG.

# chvg

Command is used to change VG.

# lsvg

Command is used to list all the VG in the system.

# importvg

Command is used to add/install a VG.

# exportvg

Command is used remove the VG from the system. we will discuss about the significance of exportvg command in detail in posts to come.

# reorgvg

Command is used to reorganize the VG.

# syncvg

Command is used to synchronize a VG.

# varyonvg

Command is used to make VG available to the system for use.

# varyoffvg

Command is used to make VG unavailable to the system.

# mirrorvg

Command is used to mirror all LV within a VG.

Happy Learning!

Steps To Extend / Reduce A VG

Extend A VG:

This post talks about the steps taken to expand / increase / extend a VG.

In our previous example, we created a VG with name oracle_vg which had 2 PVs (hdisk0, hdisk5) attached to it.

lets say, now the end user needs more space to store data on FS in this VG so end user will ask admin/administrator to expand / extend the FS. So the admin needs to extend the VG to comply to the end user requirement.

Various commands used to extend the VG are:

First, always check the free PVs available on system by running the following command:

# lspv

lets say, hdisk10 is free and can be added to oracle_vg VG.

So we run the following command:

# extendvg oracle_vg hdisk10

Next we run the lspv command to confirm the extension:

# lspv

Thus, VG is extended and now is made up of 3 PVs (hdisk0, hdisk5, hdisk10).

Reduce A VG:

Commands used to reduce VG are:

# lspv

This command is run to check which PV admin will remove from the VG.

Command to reduce the VG is:

# reducevg oracle_vg hdisk10

Remember : Only those PVs can be removed for which PPs are free. a PV whose PPs are in use can never be removed from a VG.

Confirm the removal using the command:

# lspv

Next post will discuss about the steps to create a LV with Mirroring.

till then, Happy Learning !