A restore re-creates database server data from backed-up storage spaces and logical-log files. A restore re-creates database server data that has become inaccessible because of any of the following conditions:
To restore data up to the time of the failure, you must have at least one level-0 backup of each of your storage spaces from before the failure and the logical-log files that contain all transactions since these backups.
When you restore data, you must decide whether to do so while the database server is in quiescent, online, offline (Dynamic Server), or microkernel mode (Extended Parallel Server). The types of restores are as follows:
As Figure 3 shows, a warm restore restores noncritical storage spaces. A warm restore consists of one or more physical restores, a logical-log backup, and a logical restore.
As Figure 4 shows, a cold restore salvages the logical logs, and restores the critical dbspaces (root dbspace and the dbspaces that contain the physical log and logical-log files), other storage spaces, and the logical logs.
You can perform a cold restore onto a computer that is not identical to the one on which the backup was performed by giving any chunk a new pathname and offset during the restore.
ON–Bar and ontape restore database server data in two phases:
During a physical restore, ON–Bar or ontape restores the data from the most recent level-0, level-1, and level-2 backups. When you suffer a disk failure, you can restore to a new disk only those storage spaces with chunks that resided on the failed disk. Figure 5 illustrates a physical restore.
As Figure 6 shows, the database server replays the logical logs to reapply any database transactions that occurred after the last backup. The logical restore applies only to the physically-restored storage spaces.
For more information, see Restoring Data with ON-Bar and Restoring with ontape.
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