New Features of Oracle10g backup set Compression (Backupset Compression)

Oracle10g backup set Compression new feature (Backupset Compression) Oracle10g allows you and the BACKUP command to compress the BACKUP set using the as compressed backupset statement. This compression backup does not need to be decompressed during recovery, which may be very beneficial under the following conditions: www.2cto.com 1. your backup storage space is limited. 2. network backup with limited bandwidth 3. direct BACKUP to tape, CD, and DVD media. compression is not available. You can choose to display the specified compression option in the BACKUP command: backup as compressed backupset database plus archivelog; -- only BACKUP for files compressed as compressed backupset datafile; you can also configure rman to specify the compression option: configure device type disk parallelism 1 backup type to compressed backupset; however, compressed backup will consume more resources and time. Let's take a look at the following tests: www.2cto.com 1. compression backup note compression backup time: 00: 08: 35 + 00: 00: 07 = 522 s 2. non-compressed backup non-compressed backup time: 00:01:55 + 00:00:07 = 122s compression backup time is not compressed: 522/122 = 4.28 times. 3. compression Ratio compression backup size: 190103552 + 1093632 = 182.33984375 M non-compressed backup set: 1130618880 + 1302528 = 1079.484375 M non-compressed compared with the compression size: 1079.484375/182.33984375 = 5.9 times the compression method greatly saves space. 4. CPU consumption compression backup CPU consumption: pid username thr pr nce size res state time flts cpu command 15252 oracle 11 10 0 430 M 353 M cpu01 0 26.35% oracle about 26%. CPU consumption in non-compression mode: pid username thr pr nce size res state time flts cpu command 15252 oracle 11 52 0 445 M 364 M sleep 57 16.43% oracle about 16% compression mode more than non-compression mode consumes about 10% CPU Rman compressed is divided into three types, the first two are default values. The latter type must be manual. 1. null compression 2. unused block compression 3. binary compression is null compression by default before version 10.1, and 1 + 2 by default after Version 10.2. The following three terms are explained: www.2cto.com null compression: unallocated blocks will not be backed up during rman backup. Unused block compression: even if the block has been allocated, the data is deleted. The data in the delete part will not be backed up as an example. I now have a datafile 100 m. If 50 m blocks have been allocated, but 25 m has been deleted, if 50 m is backed up in version 10.1 and 25 m is backed up after Version 10.2. binary compression: manually add the as compressed command when executing the rman command. When the disk space is insufficient, you can consider the compression and backup feature. The compression ratio is amazing. It can reach 1/2-1/4. However, this kind of high compression also has shortcomings. That is, recovery is slow. This is mainly measured between disks and CPUs. The zlib compression algorithm is released at 11 GB, which is faster than before. However, the compression ratio is not as good as the previous bzip2.