You can use copy storage pools and active-data pools to
protect the data in primary storage pools. Copy storage pools can
contain any combination of active and inactive data, archive data,
or space-migrated data. Active-data pools contain only active versions
of client backup data.
Before you begin
Restoring a primary storage pool from an active-data pool
might cause some or all inactive files to be deleted from the database
if the server determines that an inactive file needs to be replaced
but cannot find it in the active-data pool.
As a best practice,
therefore, and to prevent the permanent loss of inactive versions
of client backup data, you should create a minimum of one active-data
pool, which contains active-data only, and one copy storage pool,
which contains both active and inactive data. To recover from a disaster,
use the active-data pool to restore critical client node data, and
then restore the primary storage pools from the copy storage pool.
Do not use active-data pools for recovery of a primary pool or volume
unless the loss of inactive data is acceptable.
About this task
Setting up copy storage pools and active-data pools describes
the high-level steps for implementation.
Neither copy storage
pools nor active-data pools are part of a storage hierarchy, which,
by definition, consists only of primary storage pools. Data can be
stored in copy storage pools and active-data pools using the following
methods:
- Including the BACKUP STGPOOL and COPY ACTIVEDATA commands in administrative
scripts or schedules so that data is automatically backed up or copied
at regular intervals.
- Enabling the simultaneous-write function so that data is written
to primary storage pools, copy storage pools, and active-data pools
during the same transaction. Writing data simultaneously to copy
storage pools is supported for backup, archive, space-management,
and import operations. Writing data simultaneously to active-data
pools is supported only for client backup operations and only for
active backup versions.
- (copy storage pools only) Manually issuing the BACKUP STGPOOL
command, specifying the primary storage pool as the source and a copy
storage pool as the target. The BACKUP STGPOOL command backs up whatever
data is in the primary storage pool (client backup data, archive data,
and space-managed data).
- (active-data pools only) Manually issuing the COPY ACTIVEDATA
command, specifying the primary storage pool as the source and an
active-data pool as the target. The COPY ACTIVEDATA command copies
only the active versions of client backup data. If an aggregate being
copied contains all active files, then the entire aggregate is copied
to the active-data pool during command processing. If an aggregate
being copied contains some inactive files, the aggregate is reconstructed
during command processing into a new aggregate without the inactive
files.
For efficiency, you can use a single copy storage pool and
a single active-data pool to back up all primary storage pools that
are linked in a storage hierarchy. By backing up all primary storage
pools to one copy storage pool and one active-data pool, you do not
need to repeatedly copy a file when the file migrates from its original
primary storage pool to another primary storage pool in the storage
hierarchy.
In most cases, a single copy storage pool and a
single active-data pool can be used for backup of all primary storage
pools. However, the number of copy storage pools and active-data pools
you actually need depends on whether you have more than one primary
storage pool hierarchy and on the type of disaster recovery protection
you want to implement. Multiple copy storage pools and active-data
pools might be needed to handle particular situations, including the
following:
- Special processing of certain primary storage hierarchies (for
example, archive storage pools or storage pools dedicated to priority
clients)
- Creation of multiple copies for multiple locations (for example,
to keep one copy on-site and one copy off-site)
- Rotation of full storage pool backups (See Backing up primary storage pools.)
Inactive files in volumes in an active-data pool are
deleted by reclamation processing. The rate at which reclaimable space
accumulates in active-data pool volumes is typically faster than the
rate for volumes in non-active-data pools. If reclamation of volumes
in an active-data pool is occurring too frequently, requiring extra
resources such as tape drives and libraries to mount and dismount
volumes, you can adjust the reclamation threshold until the rate of
reclamation is acceptable. The default reclamation threshold for active-data
pools is 60 percent, which means that reclamation begins when the
storage pool reaches 60 percent of capacity. Note that accelerated
reclamation of volumes has more of an effect on active-data pools
that use removable media and, in particular, on removable media that
is taken off-site.