tailieunhanh - Oracle Database Administration for Microsoft SQL Server DBAs part 9

Oracle Database Administration for Microsoft SQL Server DBAs part 9 takes the administration topics with which the SQL Server DBA is familiar, translates them into Oracle terms, and then expands on Oracle functionality. Definitions and comparative terms run throughout the book so the SQL Server DBA can easily leverage existing knowledge. This Oracle Press guide also expands on some of the features in Oracle that do not match up directly with SQL Server, and looks at other processes often performed on an Oracle database that would not typically be a standard practice in SQL Server environments | 62 Oracle Database Administration for Microsoft SQL Server DBAs Are These Really .mdf Files The datafiles that make up the tablespaces in Oracle are the most similar to SQL Server s .mdf files and the redo logs could be considered similar to the .ldf files. Also if the database is not running these files can be copied for a cold backup similar to SQL Server when taking a database offline or if the instance service has been stopped to take a copy of the .mdf file and .ldf files. SQL Server databases typically have one .mdf file and one .ldf file per database. Larger databases may spread out more files across different drives using the naming convention .mdf for the primary file and .ndf for the other files. Oracle tablespaces might be compared to SQL Server filegroups but the filegroups are specific to one database to manage multiple datafiles and are not at the server level. The tablespaces are available at the server level but might be managed to allocate files to one user. Oracle tends to use the same extension for all of the datafiles. It is typical to use the tablespace name in the datafile name. For example the SYSTEM tablespace may have and the SYSAUX tablespace may have . These examples show one file for one tablespace but this is normally not the case. Especially with older versions it is typical to see several datafiles make up a tablespace. Multiple datafiles for a tablespace might be due to earlier operating system limitations to prevent the datafiles from becoming too large. Balancing the need for fewer files to manage against being able to easily restore datafiles is one of the fun tasks of a DBA. It s nice to be able to turn over this task to ASM. If faced with an application that has been around for a couple of versions of Oracle and the tablespaces seem a little on the unmanageable side it might be time to convert to ASM. More Files to Manage Datafiles are just some of the files needed by the Oracle database. Then there are