7.7.4.5 CREATE FLASHLOG

Purpose

The CREATE FLASHLOG command creates the Oracle Exadata Smart Flash Log on a cell for redo log write requests.

Syntax

CREATE FLASHLOG { ALL [ FLASHDISK ] [ size=log_size ] | 
          CELLDISK='cdisk1[,cdisk2]...' [ , size=log_size ] }

Usage Notes

The CREATE FLASHLOG command accepts a list of comma-delimited flash cell disks. If a size is specified in the command, then that size is divided evenly across the cell disks, and will total the specified size. If a size is not specified, then a default size of 512 MB is used.

The size of Oracle Exadata Smart Flash Log space on each flash disk must be less than 4 GB. If all 16 flash disks are available, then the total size of Oracle Exadata Smart Flash Log must be less than 64 GB.

Similar to space in grid disks and flash cache, flash log space is allocated in 16 MB units, referred to as allocation units. If the size attribute is specified when creating a flash log, then the size allocated is the size of the largest multiple of allocation units less than or equal to the specified size. For example, if 300M is specified for the size attribute, then 288 MB (16x18) is allocated because 288 is the largest multiple of 16 that is less than or equal to 300.

A minimum of 1 allocation unit is always allocated, so the minimum size for a flash log is 16 MB. Any size value less than 16 MB is rounded up to 16 MB.

The ALL FLASHDISK argument creates Oracle Exadata Smart Flash Log on all flash cell disks. If the ALL argument is not specified, then the CELLDISK argument must be specified. The FLASHDISK argument is not required.

Note:

The CREATE FLASHCACHE command, by default, uses all available space on each flash disk. Therefore, use the CREATE FLASHLOG command before creating the flash cache to ensure both objects consume the correct amount of flash disk space.

To change the size of the flash log, use the DROP FLASHLOG command to drop the flash log, and then use the CREATE FLASHLOG command to create a flash log with the new size.

Examples

The following example shows how to create Oracle Exadata Smart Flash Log on a cell.

Example 7-83 Creating Oracle Exadata Smart Flash Log

CellCLI> CREATE FLASHLOG ALL

CellCLI> CREATE FLASHLOG ALL SIZE=1g

CellCLI> CREATE FLASHLOG ALL FLASHDISK

CellCLI> CREATE FLASHLOG CELLDISK='fd1,fd2,fd3,fd4'