Database Reference
In-Depth Information
The file is now moved to the correct location:
SQL> alter database move datafile '/u01/oradata/cdb1/tbs_arch_01.dbf'
2 to '+DATA';
Database altered.
After the move the data file is in the correct location. The database stayed available all the time while the data
file has been moved. Notice that this was executed in a Pluggable Database. Chapter 7 explains file names in PDBs in
more detail.
SQL> select file_name from dba_data_files
2 where tablespace_name = 'TBS_ARCH_01';
FILE_NAME
--------------------------------------------------------------------------------
+DATA/CDB1/E025A74226115F1CE0436538A8C0FDF9/DATAFILE/tbs_arch_01.274.821486701
Notice that the move data file command creates a copy of the data file you are moving. In most cases this is not a
problem, but if you are short on space you should not execute multiple commands in parallel.
Data and Information Lifecycle Management
Many vendors are spending a lot of time and effort in educating users on how important it is to use Information Life
Cycle Management (ILM) on a grand scale to cut costs and become more efficient. The vendors' value propositions
are sound of course: there are many applications that do not use any kind of life cycle management at all, wasting
premium storage at high cost for all data. Since a lot of data is related to time in one way or another it would make
sense to put older—less frequently accessed data—on lower performance (read: cost) storage while keeping the other
storage on higher storage tiers.
Storage vendors of course know about that problem, and try to address it with clever software on the storage
array. Since most enterprise arrays have some sort of storage tiering built-in algorithms in software try to move the
most frequently accessed data to the fastest storage tier while keeping “cold” data on slower storage. This happens
automatically.
Storage Tiers
Storage engineers and vendors often refer to a storage tier when discussing persistent storage. The classic division of
storage in an enterprise array consists of the following tiers, sorted by performance in descending order.
Flash memory
High performance Fibre Channel disks
High capacity Fibre Channel disks
High capacity “near-line” disks
The actual implementation is of course dependent on the array vendor but most implement a high IOPS/low
latency technology for very demanding applications to very high capacity disks which are slow but cheap for data that
the business cannot decide to archive differently.
 
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