When the operating system is booted, the
root file system and
swap area must be available for use before the
vxconfigd daemon can load the VxVM configuration or start any volumes. During system startup, the operating system must see the
swapvol volumes as regular partitions so that it can access them as ordinary disk partitions.
Due to this restriction, each of the
swapvol plexes must be created from contiguous space on a disk that is mapped to a single partition. It is not possible to stripe, concatenate or span the plex of a
swapvol volume that is used for booting. Any mirrors of these plexes that are potentially bootable also cannot be striped, concatenated or spanned.
Volumes on the root disk have the following restrictions on their configuration:
rootvol) must exist in the disk group that is chosen to be the boot disk group,
bootdg. Although other volumes named
rootvolcan be created in other disk groups, only the
bootdgcan be used to boot the system.
swapvolvolumes always have minor device numbers 0 and 1 respectively. Other volumes on the root disk do not have specific minor device numbers.
swapvolvolumes are fully configured, the default volume configuration uses the overlay partition to access the data on the disk.
rootvoldevice for performance reasons, you cannot stripe the primary plex or any mirrors of
rootvolthat may be needed for system recovery or booting purposes if the primary plex fails.
swapvolcannot be spanned or contain a primary plex with multiple noncontiguous subdisks. You cannot grow or shrink any volume associated with an encapsulated boot disk (
swapvol, and so on) because these map to a physical underlying partition on the disk and must be contiguous. A workaround is to unencapsulate the boot disk, repartition the boot disk as desired (growing or shrinking partitions as needed), and then re-encapsulating.
In addition to these requirements, it is a good idea to have at least one contiguous, (cylinder-aligned if appropriate) mirror for each of the volumes for
swap. This makes it easier to convert these from volumes back to regular disk partitions (during an operating system upgrade, for example).