概述

今年都比较忙，这几天抽空整理了关于18c在 ASM管理上的一些改进方面，希望对大家有点帮助。

Oracle ASM Cluster Configuration with Oracle RAC

Changes in Oracle Automatic Storage Management 18c

1、Converting Normal or High Redundancy Disk Groups to Flex Disk Groups without Restricted Mount

You can convert a conventional disk group (disk group created before Oracle ASM 18c) to an Oracle ASM flex disk group without using the restrictive mount (MOUNTED RESTRICTED) option.

Virtual Allocation Metadata (VAM) migration must be enabled and completed before converting without the use of a restrictive mount.

这里主要指18c后可以将传统磁盘组(在Oracle ASM 18C之前创建的磁盘组)转换为Oracle ASM Flex磁盘组，而无需使用限制装载(装载限制)选项。

在转换之前，必须启用并完成虚拟分配元数据(VAM)迁移，而不使用限制性装载。

2、Dropping Oracle ASM File Groups With a Cascade Option

You can drop a file group and its associated files (drop including content) using the CASCADE keyword with ALTERDISKGROUP ... DROP FILEGROUP SQL statement.

18c后可以使用带alter diskgroup的cascade关键字删除ASM文件组及其关联的文件。

3、Oracle ASM Flex Disk Group Support for Multitenant Cloning

You can create an Oracle ASM mirror clone of a multitenant database. Oracle ASM file group properties and the SQL syntax for administering pluggable databases have been updated.

18c后可以创建多租户数据库的Oracle ASM镜像克隆。

4、Oracle ASM Miscellaneous Enhancements

You can set the CONTENT_HARDCHECK.ENABLED disk group attribute to enable or disable Hardware Assisted Resilient Data (HARD) checking when performing data copy operations .

The default value for the DISK_REPAIR_TIME disk group attribute has changed from 3.6 hours (3.6h) to 12 hours (12h).

在执行数据复制操作时，可以将content_hardcheck.enabled 磁盘组属性设置为启用或禁用硬件辅助的弹性数据(硬)检查。

磁盘修复时间磁盘组属性的默认值已从3.6小时更改为12小时。

5、Storage Conversion for Member Clusters

You can use ASMCMD commands to administer the configuration of member clusters. For example, you can change the storage method from direct Oracle ASM to indirect Oracle ASM, or change from indirect Oracle ASM to direct Oracle ASM.

18c后可以使用asmcmd命令来管理成员集群的配置。

6、Changes to ASMCMD showversion and showpatches Commands

Additional options have been provided ASMCMD showversion and showpatches commands.

提供了其他选项如asmcmd showversion和showpatches命令。

Changes in Oracle ACFS and Oracle ADVM in Oracle ASM 18c

1、Enhancements for Oracle ACFS Replication

Oracle ACFS replication provides replication role reversal functionality and the designation of an Oracle ACFS snapshot as a storage location participating in replication. Oracle ACFS replication provides replication role reversal functionality, which enables the original primary and standby locations to reverse roles. Using the acfsutil repl reverse command, you can change the original primary to the new standby, and the original standby to the new primary.

The role reversal functionality enhances replication to provide additional disaster recovery capabilities. With the designation of an Oracle ACFS snapshot as a replication primary or standby location, you can choose to replicate either a mounted file system or a snapshot of a mounted file system.

Oracle recommends Oracle Data Guard and Oracle Golden Gate for database disaster recovery. In Oracle ASM 18c and Oracle ASM 12c release 2, Oracle ACFS replication can be used with Oracle Standard Edition for disaster recovery and for periodic refreshes of test and development environments.

这里主要是对Oracle ACFS复制的增强(Oracle ACFS复制提供复制角色反转功能，并将Oracle ACFS快照指定为参与复制的存储位置。)，Oracle推荐使用DG和OGG进行数据库灾难恢复。在Oracle ASM 18C和Oracle ASM 12C第2版中，Oracle ACFS复制可与Oracle Standard Edition一起用于灾难恢复和测试和开发环境的定期刷新。

2、Reducing the Size of an Oracle ACFS File System

You can use the acfsutil size command to reduce the size of a file system whether or not the command must internally move user data or metadata to complete the action.

18C后可以使用acfsutil size命令来减小oracle ACFS文件系统的大小。

3、Oracle ACFS Remote Service for Member Clusters

In addition to support for Oracle member clusters with attached local storage, Oracle ACFS provides Oracle ACFS remote service for native Oracle ACFS functionality on member clusters with no attached local storage (indirect storage member clusters). Utilizing an Oracle ACFS deployment on the Oracle Domain Services Cluster (DSC), Oracle ACFS remote service can be used for both Oracle Application Clusters and database member clusters to enable a flexible and file system-based deployment of applications and databases. Unlike NFS-based exports, Oracle ACFS remote service fully supports advanced Oracle ACFS features; such as replication, snapshots, and tagging; on the destination member cluster.

18c后Oracle ACFS增加了为没有附加本地存储的成员群集(间接存储成员群集)上的本机Oracle ACFS功能提供Oracle ACFS远程服务。

4、Additional Information Displays for Oracle ACFS Storage Usage

You can use the acfsutil info storage command to display a platform independent view that shows how the space in an Oracle ASM disk group is consumed by components of Oracle ASM, Oracle ACFS, and Oracle ADVM.

可以使用acfsutil info storage命令显示一个独立于平台的视图，该视图显示Oracle ASM磁盘组中的空间是如何被Oracle ASM、Oracle ACF和Oracle ADVM的组件占用的。

5、Enhancements to Oracle ACFS Snapshot Commands

Oracle ACFS acfsutil commands have been updated to provide better management of Oracle ACFS snapshots.

You can create or delete snapshot links with the acfsutil snap link command. A snapshot link provides access to the contents of a snapshot using an alternate path which does not include the .ACFS/snaps directory, the default location where snapshots are created.

对ACFS快照命令的增强，可以使用acfsutil snap link命令来创建或删除快照链接。

6、Temporarily Freezing Modification in an Oracle ACFS File System

You can use the acfsutil freeze and acfsutil thaw commands to temporarily halt and resume modification activity in an Oracle ACFS file system. Using the acfsutil freeze command, you can create point-in-time images across different snapshots without stopping your applications. Cross-node communication ensures that all nodes perform a freeze operation. During the freeze, each node stops all modification operations on the specified file system, flushes user data and metadata, commits the data to disk, and then acknowledges when the operations are completed.

修改了ACFS文件系统临时冻结特性，使用acfsutil freeze和acfsutil thaw命令临时停止和恢复Oracle acfs文件系统中的修改活动。在冻结期间，每个节点停止指定文件系统上的所有修改操作，刷新用户数据和元数据，将数据提交到磁盘，然后在操作完成时确认。

7、Enhancements to Oracle ACFS Diagnostic Commands

Oracle ACFS diagnostic commands, such as acfsutil meta, have been updated to provide improved diagnostic management of Oracle ACFS.

对Oracle ACFS诊断命令的增强(例如acfsutil meta)

篇幅有限，大概介绍下Oracle ASM 18C中Oracle acfs和Oracle advm的变化和ASM上的一些更改，这里主要是Oracle Flex ASM特性，这个特性可以使ASM实例和数据库实例在不同的节点上运行，而不是之前的ASM实例必须和数据库实例运行在同一个节点上。也就是说当某个节点上的ASM 实例挂掉后，其上的数据库实例还可以正常运行。在Oracle 12c中，在创建数据库的时候还需要选择是否启用Oracle Flex 集群和Flex ASM，但是到了18c中，默认就是Flex 集群和Flex ASM，不再需要选择。

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