Calculating Reserve Volume Capacity - Sun Microsystems StorageTek 6140 Administration Manual

The following options are available:
Automatic – The management software automatically searches for and selects a
virtual disk that matches the necessary criteria. If there are none, and enough
space is available, it creates a new virtual disk.
Create Volume on an Existing Virtual Disk – You manually select the virtual
disks on which you want to create the volume from the list of all available
virtual disks. Be sure that the number of disks you select have enough capacity
for the volume.
Create a New Virtual Disk – You create a new virtual disk on which to create
the volume. Be sure that the virtual disk that you create has enough capacity
for the volume.
The snapshot mapping option
You can add the snapshot to an existing storage domain, including the default
storage domain, or create a new storage domain by mapping the snapshot to a
host or host group. A storage domain is a logical entity used to partition storage
that allows a host or host group to have read/write access to the snapshot. The
default storage domain contains all hosts and host groups without explicit
mappings and enables them to share access to all snapshots that are not explicitly
mapped.
During snapshot creation, you can choose between the following mapping
options:
Map Snapshot to One Host or Host Group - this option enables you to
explicitly map the snapshot to a specific host or host group, or to include the
snapshot in the default storage domain.
Do Not Map this Snapshot - this option causes the management software to
automatically include the snapshot in the default storage domain.
Note: A host or host group will be available as a mapping option only if an
initiator is associated with each individual host and each host included in a host
group.

Calculating Reserve Volume Capacity

When you create a snapshot, you specify the size of the snapshot reserve volume
that will store snapshot data and any other data that is needed during the life of the
snapshot. When prompted to specify the size of the snapshot reserve volume, you
must enter a percentage of the size of the base volume, as long as that percentage
does not translate to a size of less than 8 megabytes.
Chapter 4 Configuring Volume Snapshots 73