You can drop one or more storage paths from a storage group
or you can move data off the storage paths and rebalance them.
Before you begin
To determine whether permanent table spaces are using the
storage path, use the ADMIN_GET_STORAGE_PATHS administrative view.
This view displays current information about the storage paths for
each storage group. A storage path can be in one of three states:
- NOT_IN_USE
- The storage path has been added to the database but is not in
use by any table space.
- IN_USE
- One or more table spaces have containers on the storage path.
- DROP_PENDING
- An ALTER STOGROUP stogroup_name DROP statement
has been issued to drop the path, but table spaces are still using
the storage path. The path is removed from the database when it is
no longer being used by a table space.
If the storage path you dropped has data stored
on it and is in the DROP_PENDING state, you must rebalance all permanent
table spaces using the storage path before the database manager can
complete the drop of the path.
To obtain information about table
spaces on specific database partitions use the MON_GET_TABLESPACE
administrative view.
Restrictions
A
storage group must have at least one path. You cannot drop all paths
in a storage group.
About this task
If you intend to drop a storage path, you must rebalance
all permanent table spaces that use the storage path by using ALTER
TABLESPACE tablespace-name REBALANCE, which moves data off the path
to be dropped. In this situation, the rebalance operation moves data
from the storage path that you intend to drop to the remaining storage
paths and keeps the data striped consistently across those storage
paths, maximizing I/O parallelism.
Procedure
- To drop storage paths from a storage group, issue the following
ALTER STOGROUP statement:
ALTER STOGROUP sg DROP '/db2/filesystem1', '/db2/filesystem2'
where sg is
the storage group and /db2/filesystem1 and /db2/filesystem2 are
the storage paths being dropped.
- Rebalance the containers of the storage paths being dropped.
To determine all the affected permanent table spaces in the database
that have containers residing on a "Drop Pending" path, issue the
following statement:
SELECT TBSP_NAME
FROM table (MON_GET_TABLESPACE(' ', -2))
WHERE TBSP_USING_AUTO_STORAGE = 1
AND TBSP_CONTENT_TYPE IN ('ANY','LARGE')
AND STORAGE_GROUP_NAME = 'sg'
ORDER BY TBSP_ID
Once the table spaces have been identified,
you can perform the following statement for each of the table spaces
listed: ALTER TABLESPACE tablespace_name REBALANCE
where tablespace_name is
a table space. After the last rebalance operation is complete, /db2/filesystem1 and /db2/filesystem2 are
removed from the storage group.
- Drop the temporary table spaces using the storage group.
A table space in DROP_PENDING state is not dropped if there is a temporary
table space on it.
- Re-create the temporary table spaces that were using the
storage group.
What to do next
Query the ADMIN_GET_STORAGE_PATHS administrative view
to verify that the storage path that was dropped is no longer listed.
If it is, then one or more table spaces are still using it.