ACPI stands for Advanced Configuration and Power Interface. It is the system that controls hardware actions such as the dynamic speed fans, the power button behavior, system sleep states, and helps to identify some system capabilities. ACPI power-saving features are hierarchical, meaning that any device running “behind” another will be dependent on the power state of the parent device. For example, a device cannot be running in full power “behind” a device that is sleeping or in standby … [Read more...] about How to disable ACPI in CentOS/RHEL 7
How to Use real-time query to access data on a physical standby database
Oracle Active Data Guard Oracle Active Data Guard increases performance, availability, data protection, and return on investment wherever Data Guard is used for real-time data protection and availability. An Oracle Active Data Guard standby database can be used to offload a primary database of reporting, ad hoc queries, data extracts, and backups, making it a very effective way to insulate interactive users and critical business tasks on the production system from the overhead of long-running … [Read more...] about How to Use real-time query to access data on a physical standby database
CentOS/RHEL 8: “ACPI MEMORY OR I/O RESET_REG” Server Hung after reboot
The Problem Rebooting the CentOS/RHEL 8 server causes it to freeze. From the console output, the system is stuck at: ... [ 68.906159] dracut: Disassembling device-mapper devices Rebooting. [ 68.934073] kvm: exiting hardware virtualization [ 68.936622] sd 0:0:0:0: [sda] Synchronizing SCSI cache [ 68.938942] e100e: EEE TX LPI TIMER: 00000011 [ 69.018502] reboot: Restarting system [ 69.020000] reboot: machine restart After removing "rhgb quiet" and adding "debug rd.debug" in grub … [Read more...] about CentOS/RHEL 8: “ACPI MEMORY OR I/O RESET_REG” Server Hung after reboot
How to Create a Physical Standby Database by Using SQL and RMAN Commands
You perform the steps listed below when using SQL and RMAN commands to create a physical standby database. These are high level steps and are explained in detail later in the blog. Prepare the primary database. Set parameters on the physical standby database. Configure Oracle Net Services. Start the standby database instance. Execute the DUPLICATE TARGET DATABASE FOR STANDBY FROM ACTIVE DATABASE RMAN command. Start the transport and application of redo. Preparing the Primary … [Read more...] about How to Create a Physical Standby Database by Using SQL and RMAN Commands
Basics of client connectivity in Oracle Data Guard configuration
Oracle Net Services Overview Oracle Net Services provide enterprise-wide connectivity solutions in distributed, heterogeneous computing environments. It enables a network session from a client application to an Oracle Database server. A dedicated server process is a type of service handler that the listener starts when it receives a client request. The slide depicts the process of establishing a connection from a client to an Oracle Database (non-shared server architecture) by using … [Read more...] about Basics of client connectivity in Oracle Data Guard configuration
ORA-354 ORA-353 and ORA-312: Possible corruption in Online Redo Log File Members in a Redo Log Group
The Problem Following errors are reported in the alert log file: ORA-354: corrupt redo log block header ORA-353: log corruption near block %s change %s time %s ORA-312: online log %s thread %s: '%s' ORA-312: online log %s thread %s: '%s' ORA-312 reports all the redo log file names for the same redo log group number. Example for redo log group number 3 which has two redo log file members: ORA-00354: corrupt redo log block header ORA-00353: log corruption near block 1892904 change 878787 … [Read more...] about ORA-354 ORA-353 and ORA-312: Possible corruption in Online Redo Log File Members in a Redo Log Group
How to relocate the redo log files to a different location on disk
Offline Method 1. Shut down the database. 2. Copy the online redo log files to the new location. Operating system files, such as online redo log members, must be copied using the appropriate operating system commands. The following example uses operating system commands (UNIX) to move the online redo log members to a new location: $ mv /diska/logs/log1a.rdo /diskc/logs/log1c.rdo $ mv /diska/logs/log2a.rdo /diskc/logs/log2c.rdo 3. Startup the database in mount mode, but do not … [Read more...] about How to relocate the redo log files to a different location on disk
Oracle Database: Redo log operations (Add/Drop/Change Location)
Question: How to add or drop online redo logs? How to change redo log file location? How to determine the optimal size for redo logs using OPTIMAL_LOGFILE_SIZE? How to add or drop online redo logs 1. Review information on existing redo logs: SELECT a.group#, b.member, a.status, a.bytes FROM v$log a, v$logfile b WHERE a.group#=b.group# 2. Add new groups: ALTER DATABASE ADD LOGFILE group 4 ('/log01A.dbf', '/log01B.dbf ') SIZE 512M; ALTER DATABASE ADD LOGFILE group 5 ('/log02A.dbf', … [Read more...] about Oracle Database: Redo log operations (Add/Drop/Change Location)
How to add and drop online redo log members and groups in Oracle
Mirroring online redo logs The Oracle database maintains online redo log files to minimize the loss of data in the database. The redo log files record all changes made to data in the database buffer cache with some exceptions; for example, in the case of direct writes. Redo log files are used in a situation such as an instance failure to recover committed data that has not been written to the data files. The redo log files are only used for recovery. Online Redo Log Groups - A set of … [Read more...] about How to add and drop online redo log members and groups in Oracle
Process are stuck in D-state due to multipathd
For multipaths with queueing enabled and with all paths down, the kernel will store submitted IOs in a queue and resubmit them upon path recovery. Process submitting IOs to these multipath are stuck in D-state (uninterruptible sleep). The 'no_path_retry 4' multipath parameter will instruct the kernel to unplug the queue after 4 failed path-tests. Unplugging the queue will fail all stored IOs. If the outage will last, the admin might wish to unplug the queues right-away. The following … [Read more...] about Process are stuck in D-state due to multipathd