What's New in Oracle Database Storage Administration?

This section describes the new storage administration features for Oracle Database 11g release 1 (11.1) and it contains the following topic:

New Automatic Storage Management Features for Oracle Database 11g Release 1 (11.1)

New Automatic Storage Management Features for Oracle Database 11g Release 1 (11.1)

This section describes the following Oracle Database 11g release 1 (11.1) Automatic Storage Management (ASM) features:

Oracle Database Storage Administrator's Guide is New for this Release

This book, the Oracle Database Storage Administrator's Guide, is new for Oracle Database 11g release 1 (11.1) and it is the primary information source for Oracle Automatic Storage Management features.
ASM Fast Mirror Resync

ASM fast mirror resync quickly resynchronizes ASM disks within a disk group after transient disk path failures as long as the disk drive media is not corrupted. Any failures that render a failure group temporarily unavailable are considered transient failures. Disk path malfunctions, such as cable disconnections, host bus adapter or controller failures, or disk power supply interruptions, can cause transient failures.

The duration of a fast mirror resync depends on the duration of the outage. The duration of a resynchronization is typically much shorter than the amount of time required to completely rebuild an entire ASM disk group.

See Also:
"ASM Fast Mirror Resync" for more information about ASM fast mirror resync
ASM Rolling Upgrade

You can now place an ASM Cluster in rolling upgrade mode, which enables you to operate with mixed ASM versions starting with Oracle Database 11g release 1 (11.1) and later. As a result, ASM nodes can be independently upgraded or patched without affecting database availability.

See Also:
"Using ASM Rolling Upgrades" for more information about ASM rolling upgrade
New SYSASM Privilege and OSASM operating system group for ASM Administration

This feature introduces a new SYSASM privilege that is specifically intended for performing ASM administration tasks. Using the SYSASM privilege instead of the SYSDBA privilege provides a clearer division of responsibility between ASM administration and database administration.

OSASM is a new operating system group that is used exclusively for ASM. Members of the OSASM group can connect as SYSASM using operating system authentication and have full access to ASM.

See Also:
"Authentication for Accessing ASM Instances" for more information about the SYSASM privilege
ASM Scalability and Performance Enhancements

ASM file extent management has been enhanced to improve performance and to use significantly less SGA memory to store file extents. When ASM files increase in size, the size of each new extent also increases automatically so that fewer extent pointers are required to describe the file. This feature improves performance when accessing ASM files that are 20 GB and larger, up to 128 TB. Very large databases (VLDBs) often require these large file sizes. In addition, when you create new disk groups you now have multiple allocation unit size options such as 1, 2, 4, 8, 16, 32, and 64. You might obtain significant performance improvements by selecting larger AUs depending on the type of workloads (typically large sequential I/O) and storage system types.

See Also:
"Extents" for more information about scalability and performance enhancements
New ASM Command Line Utility (ASMCMD) Commands and Options

ASMCMD has the following four new commands: lsdsk, md_backup, md_restore and remap. In addition, you can use new options for the ls and lsdg commands. The following describes the four new ASM commands:
- cp—Enables you to copy files between ASM disk groups on local instances and remote instances.
- lsdsk—ASM can list disk information with or without a running ASM instance. This is a useful tool for system or storage administrators who want to obtain lists of disks that an ASM instance uses.
- md_backup and md_restore—These commands enable you to re-create a pre-existing ASM disk group with the same disk path, disk name, failure groups, attributes, templates and alias directory structure. You can use md_backup to back up the disk group environment and use md_restore to re-create the disk group before loading from a database backup.
- remap—You can remap and recover bad blocks on an ASM disk in normal or high redundancy that have been reported by storage management tools such as disk scrubbers. ASM reads from the good copy of an ASM mirror and rewrites these blocks to an alternate location on disk.
See Also:
"ASMCMD Command Reference" for more information about new and enhanced ASMCMD commands
Enhancements to ALTER DISKGROUP, CREATE DISKGROUP, and DROP DISKGROUP to manage Automatic Storage Management disk groups

The ALTER DISKGROUP, CREATE DISKGROUP, and DROP DISKGROUP SQL statements have been enhanced with additional options.
- CREATE DISKGROUP and ALTER DISKGROUP have new syntax that lets you set various attributes of a disk group.
- The CHECK clause of ALTER DISKGROUP has simplified syntax for checking the consistency of disk groups, disks, and files in an Automatic Storage Management environment.
- The MOUNT clause of ALTER DISKGROUP offers new options when mounting a disk group.
- The ONLINE and OFFLINE clauses of ALTER DISKGOUP let you take a disk offline for repair and then bring it back online.
- The FORCE keyword of DROP DISKGROUP lets you drop a disk group that can no longer be mounted by an ASM instance.
See Also:
Chapter 4, "Administering ASM Disk Groups" for more information about administering disk groups with the ALTER DISKGROUP, CREATE DISKGROUP, and DROP DISKGROUP SQL statements.
New Attributes for Disk Group Compatibility

To enable some of the new ASM features, you can use two new disk group compatibility attributes, COMPATIBLE.RDBMS and COMPATIBLE.ASM. These attributes specify the minimum software version that is required to use disk groups for the database and for ASM respectively. This feature enables heterogeneous environments with disk groups from both Oracle Database 10g and Oracle Database 11g. By default, both attributes are set to 10.1. You must advance these attributes to take advantage of the new features.

See Also:
"Disk Group Compatibility" for more information about disk group compatibility
ASM Preferred Read Failure Groups

This feature is useful in extended clusters where remote nodes have asymmetric access with respect to performance. This enables more efficient use of network resources by eliminating the need to use the network to perform read operations.

ASM in Oracle Database 10g always reads the primary copy of a mirrored extent set. In Oracle Database 11g, when you configure ASM failure groups it might be more efficient for a node to read from a failure group that is closest to the node, even if it is a secondary extent. You can configure your database to read from a particular failure group extent by configuring preferred read failure groups.

See Also:
"Preferred Read Failure Groups" for more information about preferred read failure groups
ASM Fast Rebalance

Rebalance operations that occur while a disk group is in RESTRICTED mode eliminate the lock and unlock extent map messaging between ASM instances in Oracle RAC environments, improving overall rebalance throughput.