Q: What is Oracle ASM and what are its benefits compared to traditional file systems?
Ans: Oracle ASM is a volume manager and file system that provides disk management for Oracle database files. Its benefits over traditional file systems include automatic load balancing, fast mirroring and protection of disk failure, simplified disk administration, and improved performance.
Q: What are the different types of disk groups in Oracle ASM and what is their purpose?
Ans: There are two types of disk groups in Oracle ASM: Normal and High Redundancy. Normal disk groups have a single mirror, while High Redundancy disk groups have two or more mirrors. The purpose of disk groups is to provide disk storage for Oracle database files, including data files, control files, and redo logs.
Q: How does Oracle ASM handle disk failure and what is the role of ASM disk rebalancing in this process?
Ans: Oracle ASM automatically detects disk failure and redistributes the data to surviving disks in the disk group. ASM disk rebalancing is a process that dynamically redistributes data within a disk group to improve performance and balance disk utilization.
Q: How does Oracle ASM handle disk addition and removal in a disk group?
Ans: Disk addition and removal in an Oracle ASM disk group can be done dynamically, without affecting database operations. Oracle ASM automatically redistributes data to balance utilization and protect against disk failures.
Q: What is ASMCMD and how is it used in Oracle ASM administration?
Ans: ASMCMD is a command-line interface for Oracle ASM administration. It provides a flexible and efficient way to perform routine and complex administration tasks, such as creating disk groups, adding and removing disks, and managing disk attributes.
Q: How does Oracle ASM handle data redundancy and what is the role of failure groups in this process?
Ans: Oracle ASM provides data redundancy by automatically mirroring data across multiple disks in a disk group. Failure groups are a logical grouping of disks within a disk group that share common failure characteristics, such as being in the same disk enclosure. Oracle ASM uses failure groups to ensure that data is protected against multiple disk failures within a single failure group.
Q: What is the role of ASM instance in the context of an Oracle database and how is it different from a database instance?
Ans: An ASM instance is a separate instance in an Oracle database that manages the storage of database files in ASM disk groups. It is different from a database instance, which is responsible for managing the database itself, including managing the data stored in the database.
Q: How can you monitor the performance of an Oracle ASM disk group and what are the key performance metrics to be monitored?
Ans: The performance of an Oracle ASM disk group can be monitored using performance views and tools such as the ASM Dynamic Performance (ADDM) and the Oracle Enterprise Manager. Key performance metrics to be monitored include disk space utilization, disk latency, read and write I/O rates, and disk rebalancing activity.
Q: What is the difference between ASM Striping and Disk Striping and how does it affect database performance?
Ans: ASM Striping refers to the way in which data is spread across multiple disks in an Oracle ASM disk group. Disk Striping refers to the way in which data is spread across multiple physical disks in a traditional file system. ASM Striping provides improved performance over Disk Striping as it provides automatic load balancing, improved I/O performance, and increased availability.
Q: How can you migrate a database from a traditional file system to Oracle ASM and what are the benefits of this migration?
Ans: To migrate a database from a traditional file system to Oracle ASM, you can use tools such as Data Pump or RMAN to perform a full database export and import. The benefits of this migration include improved performance, increased availability, simplified disk administration, and improved data protection.
Q: What is the role of Oracle ASM Filter Driver (ASMFD) in Oracle ASM 19c and how does it improve database performance?
Ans: Oracle ASM Filter Driver (ASMFD) is a new feature introduced in Oracle ASM 19c. It helps to reduce the overhead associated with disk I/O operations by filtering and processing disk I/O requests at the ASM layer, reducing the number of I/O requests that need to be passed to the underlying storage system. This results in improved database performance and reduced overhead.
Q: What are the new features of Oracle ASM 19c for disk group management and how do they simplify disk administration?
Ans: Oracle ASM 19c introduces several new features for disk group management that simplify disk administration. Some of the key features include:
Disk Group Compression: Allows you to reduce the storage footprint of an Oracle ASM disk group by compressing data at the disk group level.
Automatic Disk Group Management: Enables you to automate disk group management tasks, such as disk group rebalancing and disk group repair, by setting policies and thresholds.
Disk Group Resizing: Allows you to dynamically increase or decrease the size of a disk group, without taking the disk group offline.
Q: How does Oracle ASM 19c improve data protection and disaster recovery?
Ans: Oracle ASM 19c provides several features to improve data protection and disaster recovery, including:
Flexible Redundancy: Allows you to specify the level of data redundancy at the disk group level, giving you more control over data protection and disaster recovery.
Fast Disk Group Failover: Improves the failover time for disk groups in the event of disk failure, by reducing the time it takes to redirect I/O operations to surviving disks.
ASM Fast Recovery Area: Allows you to use Oracle ASM disk groups as a fast recovery area, providing improved performance and disk space utilization for backup and recovery operations.
Q: What are the benefits of using Oracle ASM Dynamic Volume Manager (ADVM) in Oracle ASM 19c?
Ans: Oracle ASM Dynamic Volume Manager (ADVM) is a new feature in Oracle ASM 19c that allows you to manage and access your Oracle ASM disk groups using standard file system commands, such as mkdir and ls. Some of the benefits of using ADVM include:
Improved Usability: Makes it easier to manage and access Oracle ASM disk groups, by allowing you to use familiar file system commands.
Improved Performance: Improves the performance of I/O operations by filtering and processing I/O requests at the ASM layer.
Improved Integration: Enables you to integrate your Oracle ASM disk groups with other file systems and applications, by allowing them to access the disk groups as standard file systems.
Q: What is the role of Oracle ASM Dynamic Rebalance in Oracle ASM 19c and how does it improve database performance?
Ans: Oracle ASM Dynamic Rebalance is a new feature in Oracle ASM 19c that helps to optimize disk utilization and improve database performance by automatically balancing the distribution of data across the disks in an Oracle ASM disk group. The dynamic rebalancing process can be triggered by adding or removing disks from a disk group, or by changing the redundancy level of the disk group. The benefits of using Oracle ASM Dynamic Rebalance include:
Improved Performance: Improves the performance of I/O operations by optimizing disk utilization and reducing disk I/O contention.
Increased Availability: Increases the availability of the disk group by reducing the risk of disk I/O performance degradation.
Automated Management: Simplifies disk group management by automating the rebalancing process and reducing the need for manual intervention.
Q: How does Oracle ASM 19c improve data protection and disaster recovery in the cloud environment?
Ans: Oracle ASM 19c provides several features that improve data protection and disaster recovery in cloud environments, including:
Cloud-Native Disaster Recovery: Allows you to configure and implement disaster recovery solutions for Oracle ASM disk groups using cloud-native features, such as snapshots and block-level replication.
Cloud-Native Backup and Recovery: Enables you to perform backup and recovery operations for Oracle ASM disk groups using cloud-native features, such as object storage and backup automation.
Cloud-Native Data Migration: Allows you to migrate data between on-premises and cloud-based Oracle ASM disk groups using cloud-native features, such as data transfer services and cloud-to-cloud migration tools.
Q: What are the benefits of using Oracle ASM 19c for Oracle Database Exadata deployments?
Ans: Oracle ASM 19c provides several benefits for Oracle Database Exadata deployments, including:
Improved Performance: Improves the performance of I/O operations by providing advanced disk management features, such as ASM Dynamic Rebalance and ADVM.
Increased Availability: Increases the availability of the disk group by providing advanced data protection and disaster recovery features, such as Flexible Redundancy and Fast Disk Group Failover.
Simplified Management: Simplifies disk group management by automating tasks, such as disk group rebalancing and disk group repair, and by reducing the need for manual intervention.
Enhanced Integration: Enhances the integration of Oracle Database Exadata deployments with other Oracle Database technologies, such as Oracle RAC and Oracle Real Application Clusters, by providing a common disk management solution.
Q: What is the role of Oracle ASM in Exadata and how does it improve database performance?
Ans: Oracle ASM plays a critical role in Exadata by providing advanced disk management features that help to improve database performance. Oracle ASM is used to manage disk groups and manage the distribution of data across the disks in the disk groups. The key benefits of using Oracle ASM in Exadata include:
Improved Performance: Oracle ASM helps to improve performance by providing advanced disk management features, such as ASM Dynamic Rebalance and ADVM, which optimize disk utilization and reduce disk I/O contention.
Increased Availability: Oracle ASM increases the availability of the disk group by providing advanced data protection and disaster recovery features, such as Flexible Redundancy and Fast Disk Group Failover, which reduce the risk of disk I/O performance degradation and improve the resilience of the disk group.
Simplified Management: Oracle ASM simplifies disk group management by automating tasks, such as disk group rebalancing and disk group repair, and by reducing the need for manual intervention.
Q: How does Oracle ASM Dynamic Rebalance work in Exadata and what are the benefits of using it?
Ans: Oracle ASM Dynamic Rebalance works in Exadata by automatically balancing the distribution of data across the disks in an Oracle ASM disk group. The dynamic rebalancing process can be triggered by adding or removing disks from a disk group, or by changing the redundancy level of the disk group. The benefits of using Oracle ASM Dynamic Rebalance in Exadata include:
Improved Performance: Improves the performance of I/O operations by optimizing disk utilization and reducing disk I/O contention.
Increased Availability: Increases the availability of the disk group by reducing the risk of disk I/O performance degradation.
Automated Management: Simplifies disk group management by automating the rebalancing process and reducing the need for manual intervention.
Q: How does Flexible Redundancy work in Oracle ASM with Exadata and what are the benefits of using it?
Ans: Flexible Redundancy is a feature in Oracle ASM that provides the ability to configure different levels of redundancy for different disk groups in the same disk group. Flexible Redundancy in Oracle ASM with Exadata provides the following benefits:
Increased Flexibility: Enables administrators to configure different levels of redundancy for different disk groups based on the specific requirements of the disk group, such as criticality and performance requirements.
Improved Data Protection: Increases the protection of data stored in disk groups by providing the ability to configure disk groups with a higher level of redundancy for critical data, and a lower level of redundancy for less critical data.
Increased Availability: Increases the availability of the disk group by providing the ability to configure disk groups with a higher level of redundancy for critical data, and a lower level of redundancy for less critical data.
Q: What is the command to create an Oracle ASM disk group?
Ans: The command to create an Oracle ASM disk group is:
ASMCMD> createdg <diskgroup_name> <disk_list>
Where <diskgroup_name> is the name of the disk group, and <disk_list> is a comma-separated list of disk paths.
Q: What is the command to add a disk to an existing Oracle ASM disk group?
Ans: The command to add a disk to an existing Oracle ASM disk group is:
ASMCMD> add disk <disk_path> to diskgroup <diskgroup_name>
Where <disk_path> is the path to the disk, and <diskgroup_name> is the name of the disk group.
Q: What is the command to drop a disk from an Oracle ASM disk group?
Ans: The command to drop a disk from an Oracle ASM disk group is:
ASMCMD> drop disk <disk_path> from diskgroup <diskgroup_name>
Where <disk_path> is the path to the disk, and <diskgroup_name> is the name of the disk group.
Q: What is the command to mount an Oracle ASM disk group?
Ans: The command to mount an Oracle ASM disk group is:
SQL> alter diskgroup <diskgroup_name> mount;
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to dismount an Oracle ASM disk group?
Ans: The command to dismount an Oracle ASM disk group is:
SQL> alter diskgroup <diskgroup_name> dismount;
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to resize an Oracle ASM disk group?
Ans: The command to resize an Oracle ASM disk group is:
SQL> alter diskgroup <diskgroup_name> resize <disk_path> size=<size>;
Where <diskgroup_name> is the name of the disk group, <disk_path> is the path to the disk, and <size> is the new size of the disk.
Q: What is the command to check the status of an Oracle ASM disk group?
Ans: The command to check the status of an Oracle ASM disk group is:
ASMCMD> lsdg <diskgroup_name>
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to show the details of an Oracle ASM disk group?
Ans: The command to show the details of an Oracle ASM disk group is:
ASMCMD> lsdg <diskgroup_name>
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to list all the disks in an Oracle ASM disk group?
Ans: The command to list all the disks in an Oracle ASM disk group is:
ASMCMD> ls <diskgroup_name>
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to list all the files in an Oracle ASM disk group?
Ans: The command to list all the files in an Oracle ASM disk group is:
ASMCMD> ls <diskgroup_name>/
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to display the attributes of an Oracle ASM disk group?
Ans: The command to display the attributes of an Oracle ASM disk group is:
ASMCMD> showdg <diskgroup_name>
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to remove an Oracle ASM disk group?
Ans: The command to remove an Oracle ASM disk group is:
SQL> drop diskgroup <diskgroup_name> including contents;
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to check the state of an Oracle ASM disk group?
Ans: The command to check the state of an Oracle ASM disk group is:
ASMCMD> lsstate <diskgroup_name>
Where <diskgroup_name> is the name of the disk group.
Q: What is the command to check the status of an Oracle ASM disk group disk?
Ans: The command to check the status of an Oracle ASM disk group disk is:
ASMCMD> lsstate <diskgroup_name>/<disk_path>
Where <diskgroup_name> is the name of the disk group, and <disk_path> is the path to the disk.
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