Hot and Cold Backup in Oracle
Introduction
In Oracle basically we use either offline or Online backups, Offline backup is called as COLD backup and online backup is called HOT backup
Backups are two types---> Physical ------>Files(Control file,Data Files,Redolog files)
|---->Logical--------->Data
These Data/Files need to protect from any disaster for that we need to manage backups
Physical Backup: physical backups will have interms of Files using Hot and Cold backup we can take backups
Cold Backup:
Cold backup is a physical backup in which all the files of a database are copied without any change means it avoids the risk of copying data and hence the image copy is
can be easily moved to another system having the same operating system,it is the safest way of take back up of All data in the database that is controlfile(.ctl files),Datafiles(.dbf files)
and Redolog files(.logfiles) Cold back are not recommended to take backup for larger databases it will take more time and space consumption client will not accept down time
Process
While taking cold backup
Shutdown the instances
Complete full consistent backup
Traditional backup
Steps
1. Shutdown instances
2.Copy the Physical files using unix cp command
Note: /orabackup/prod/cold
$ mkdir -p /orabackup/prod/cold
shutdown immediate
Taking db files backup
$ cp /oradata/prod/*.dbf /orabackup/prod/cold
or
$ cp /oradata/prod
$cp * /orabackup/prod/cold
Taking Control files backup
$ cp /oradata/prod/*.ctl /orabackup/prod/cold
or
$ cp /oradata/prod
$cp * /orabackup/prod/cold
Taking redolog files backup
$ cp /oradata/prod/*.log /orabackup/prod/cold
or
$ cp /oradata/prod
$cp * /orabackup/prod/cold
Hot Backup
Hot backup is also physcial backup including the risk of copying data because during the hot backup the database is totally open and available for users that is online.when a full backup of database is required for the hotbackup
database must be running in the ARCHIVELOG mode,
Is a inconsistent backup
is incomplete backup
is a traditional backup
while hot backup ,database must be up and running also database be in archivelog mode,while in hot backup mode ,The database must be freezed can read but cannot write into datafiles so the changes are written into archivelog files tills ends,once the backup ended ,the changes are recovered into datafiles from archivelog
Process
1.archivelog mode
2.begin backup mode
3.copy the files
4.end backup
1. SQL> archive log list
2. SQL> select files #,status from v$backup;
3. SQL> alter database begin backup;
4. $ cp /oradata/prod/*.dbf /orabackup/prod/hot
5.SQL> alter database end backup
6 . SQL> alter database backup controlfile to '/orabackup/prod/hot/control01.bkp' ;
Note : Info on hot and cold backup it may be differ in your environment like production,testing,development and directory structures and naming conventions
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