Data accommodation has four levels, 0, 1, 2, 3. Among them, 0, 1 is cold backup, 2, 3 is hot spare. Generally, we take 0 levels of disaster By backup, and 1, 2, 3 is called a disaster-stricken project.
1) 0-level comparative characteristics is the local backup / local preserved cold backup. Backup tape drives are placed in the same chamber, which is difficult to avoid the impact of fire / floods on data.
2) Level 1 Casual disaster is characterized by local backup / off-site hot backup, such as putting the tape drive to the bank, which cannot avoid the impact of the earthquake.
3) The 2-level cacrestal feature is that the site is hot, which uses channel technologies such as fiber and SAN to achieve the purpose of the standby synchronous host data.
4) 3 levels of disaster relief features two-machine hot standby, two machines are mutually standby.
The log file is required when the hot spare is restored, and the data in the log is also recovered after the data section is restored.
