7.7.4.9 CREATE PMEMLOG

Purpose

The CREATE PMEMLOG command creates the persistent memory (PMEM) log on a cell for redo log write requests.

Note:

The CREATE PMEMLOG command can only be used on Exadata X8M and X9M storage server models.

Syntax

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

Usage Notes

• The ALL argument creates the PMEM log on all PMEM cell disks. If the ALL argument is not specified, then specific PMEM cell disks must be specified by using the CELLDISK argument. The PMEM log is spread as evenly as possible across the PMEM cell disks.

• PMEM log space is allocated in 16 MB chunks, referred to as allocation units, with a minimum of 1 allocation unit. Consequently, when the size argument is specified, the actual space allocated to the PMEM log is at least 16 MB or the largest multiple of 16 MB that is less than or equal to the specified size. For example, if size=300M is specified, then 288 MB is allocated using 18 allocation units.

• If a size is not specified, then a default size is used. Commencing with Oracle Exadata System Software version 20.1.0, the default size is 10176 MB (9.9375 GB). Previously, the default size was 960 MB.

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

• On Exadata X8M and X9M systems with Oracle Exadata System Software release 23.1.0, you can interchangeably use CREATE XRMEMLOG instead of CREATE PMEMLOG.

Note:

By default, the CREATE PMEMCACHE command uses all available space on each PMEM cell disk. Therefore, it is recommended to create the PMEM log before the PMEM Cache to ensure that both objects are accommodated.

Examples

The following example shows how to create the PMEM log on a cell.

Example 7-88 Creating the PMEM Log

To create the PMEM log using the default size spread across all available PMEM cell disks, use the following command:

CellCLI> CREATE PMEMLOG ALL

To create the PMEM log with a size of 1 GB spread across all available PMEM cell disks, use the following command:

CellCLI> CREATE PMEMLOG ALL SIZE=1g

To create the PMEM log using the default size spread across specific PMEM cell disks, use the following command:

CellCLI> CREATE PMEMLOG CELLDISK='PM_01_mycell,PM_02_mycell,PM_03_mycell,PM_04_mycell'

To create the PMEM log with a size of 1 GB spread across specific PMEM cell disks, use the following command:

CellCLI> CREATE PMEMLOG CELLDISK='PM_01_mycell,PM_02_mycell,PM_03_mycell,PM_04_mycell', size=1G