OCP-1Z0-053-V12.02-146题

146.You want to take the backup of the USERS tablespace. It has a single data file of 900 MB. You have

tape drives of 300 MB each. The SBT channel is configured for the RMAN. To accomplish the backup,

you issued the following RMAN command:

RMAN> BACKUP SECTION SIZE 300M TABLESPACE users;

Which two statements are true regarding the execution of the above command? (Choose two.)

A. The RMAN parallelizes the backup although the parallelism is not set for a channel.

B. The backup piece size will be limited to 300 MB.

C. The operation is accomplished using the default channel available.

D. Three channels for the tape drive must be configured by setting the parallelism to three.

Answer: BC

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/backup.112/e10643/rcmsynta007.htm#RCMRF90025

A,错误，如果没有设置并行度，那么备份时只能只用默认的configure里面配置的并行度执行，但是默认并行度为1，即只能通过一个通道来备份，并不是并行备份的。

B,正确，指定每个备份的大小为300M，所以每个备份片被限制为300M

C,正确，使用默认的可用的通道来完成备份，正确的。

D,错误，不是一定，只是，多配置几个通道，速度会更快点，但不是一定要配置3个，使用默认的一个通道也可以备份的。

SECTION SIZE sizeSpec

Specifies the size of each backup section produced during a data file backup. By setting this parameter, RMAN can create a multisection backup. In a multisection backup, RMAN creates a backup piece that contains one file section, which is a contiguous range of blocks in a file. All sections of a multisection backup are the same size. You can create a multisection backup for a data file, but not a data file copy. File sections enable RMAN to create multiple steps for the backup of a single large data file. RMAN channels can process each step independently and in parallel, with each channel producing one section of a multisection backup set. If you specify a section size that is larger than the size of the file, then RMAN does not use multisection backup for the file. If you specify a small section size that would produce more than 256 sections, then RMAN increases the section size to a value that results in exactly 256 sections. Depending on where you specify this parameter in the RMAN syntax, you can specify different section sizes for different files in the same backup job. Note: You cannot use SECTION SIZE with MAXPIECESIZE or with INCREMENTAL LEVEL 1.