| backup
& recovery |
| Flashback
Enhancements: |
|
|
|
 |
The
flashback feature introduced in Oracle 9i has been considerably
improved in 10g. Having set things up appropriately, flashback
data is written to flashback logs on the local filesystem
and using these, you can flashback an entire database to
a previous moment in time - much quicker than restoring from
a backup and rolling forward with archivelogs. With the aid
of the new Recycle Bin feature you can flashback tables to
before they were dropped and even flashback queries and transactions. |
|
| Flash
Recovery Area: |
|
|
|
| This
is an area of disk space designed to allow you to keep all
your recovery-related database files in a single location.
You set a size for the flash recovery area although this
is a soft limit rather than hard disk limit. Files to go
in here are RMAN backup sets and controlfile backups; redo
log files; control files; archivelog files and flashback
log files. You can use the RMAN “backup recovery area” command
to back up the entire flash recovery area to tape or another
disk. |
|
| Recovery
through Resetlogs: |
|
|
|
| This
is now possible using an additional tag in the archive_log_format
init.ora parameter. The new %r format command shows which
incarnation of the database the log refers to as well as
the thread and sequence number. |
|
| RMAN
- Backup Command Changes: |
|
|
|
| The
backup and copy commands have been merged together into just
the backup
command. To do a file copy backup you can use the “backup
as copy” syntax to over-ride the default creation of
backup sets. |
|
| RMAN
- Restore Failover: |
|
|
|
| During
the restore process, RMAN can now automatically failover
to a copy of a backup piece if the original is for some reason
not available. If no copy can be found then it can fail over
to an earlier backup piece and just roll forward with more
archivelogs. |
|
| RMAN
- Fast Incremental Backup: |
|
|
|
| With the
addition of the Block Change Tracking feature, incremental
RMAN backups can be done in a fraction of the time of level
zero backups. An external file is configured on the server
which keeps track of any changed blocks since the last backup,
this information is then used to only backup those blocks. |
|
| RMAN
- Incrementally Updated File Copy Backups: |
|
|
|
|
Perhaps
one of the best new RMAN enhancements is the ability to just
update your backup sets instead of backing up the whole database
every night. Provided you have enough disk space to keep
your backups online, RMAN can initially create a file copy
backup of the database and then update these copies using
available incremental backups every time the “recover
copy of database” command is issued. |
|
|
|
 |
| RMAN
- User-catalogued Backup Pieces: |
|
|
|
Of
great relief to many DBAs will be the fact that you can
now manually add a backup piece into the RMAN catalogue
using
the CATALOG command. This means that if you have created
an image copy of your own, or if you have simply had to
move a backup piece to another location, you can now attach
it
manually to the controlfile or recovery catalogue so it
can be used in recoveries. This means that if you cannot
replicate
the exact location of your backup directory when restoring
on a new server, you can still make use of files at a different
location. It also means that you can use backups even if
you had to recreate your controlfile. |
|
| RMAN
- Channel Failover: |
|
|
|
|
|
| If
you are using multiple channels in an RMAN operation, the
process can automatically failover between channels if a
particular channel encounters an error. |
|
| RMAN
- Binary Compression for Backup Sets: |
|
|
|
| RMAN
already compresses backups by not backing up unused data
blocks but with 10g you can take this even further and apply
binary compression to backup sets to further reduce disk
usage. |
|
| SYSAUX
Tablespace: |
|
|
|
| This
new tablespace sits alongside the SYSTEM tablespace and serves
the purpose of keeping system-related schemas out of the
SYSTEJM tablespace. This includes AWR data, Log Miner data,
Streams, Oracle Text and Oracle Spatial. You can also put
any of your own schemas in there as you see fit. |
|
| RMAN
- Backup Duration and Throttling: |
|
|
|
|
It
is now possible to configure RMAN to terminate a backup after
a specified amount of time or to throttle a backup process
in order to minimise the load on the server. |
|
|
|
|
|
| |
<<
previous page |
|
next
page >> |
|
020 8465 9100 
Sales
Enquiries
Other Enquiries
