Use the vxassist mirror command to add a mirror to an existing site-based volume.

vxassist [-b] [-o notrackalign] [-g<DynamicDiskGroupName>] mirror <VolumeName|DriveLetter|VmName|DrivePath> [type=stripe] [<alloc_attributes ...>] [Column=N] [StripeUnit=<width>] [Site=<sitename1>[,<sitename2>,...]] [<[!]diskname | p#c#t#l#> ...]

See vxassist mirror.

For example, run the following command:

vxassist -g testdg mirror testvol Site=s1

Here, testvol is a Site Confined volume residing on-site s1. This creates a mirror of volume (testvol) on disks belonging to site (s1.) .

For example, run the following command:

vxassist -g testdg mirror testvol mirror=2 Site=s2,s3

Here, testvol is a Site Separated volume residing on-site s1. This creates two mirrors of volume (testvol) with one plex on disks belonging to site (s2) and other on disks belonging to site (s3).