Question: How to configure /etc/cups/cupsd.conf to allow certain user or group to manage cups tasks just like root user? By default, CUPS is configured to allow only the root user to perform tasks via the command line or via a Web-UI. For example, to add user john to be able to manage print jobs, below edit can be done: <Limit Send-Document Send-URI Hold-Job Release-Job Restart-Job Purge-Jobs Set-Job-Attributes Create-Job-Subscription Renew-Subscription Cancel-Subscription … [Read more...] about How To Add Standard Linux Users To Manage Print Jobs And Services in CentOS/RHEL
Oracle RMAN : Block-Level Media Recovery (Basics and Example)
Restriction The data file header block (block 1) cannot be recovered. Block-level Media Recovery is most useful in situations where only a small subset of blocks in a datafile need media recovery. Before Oracle9i if a single block required recovery the DBA would need to restore the complete datafile and apply all redo changes. Recovery time is reduced as only blocks needing recovery need to be restored from backup and only the required set of corrupt blocks undergo redo application. Data … [Read more...] about Oracle RMAN : Block-Level Media Recovery (Basics and Example)
Oracle RMAN – Restore and Recovery of a Noarchivelog Database
Restore and Recovery of a NOARCHIVELOG database using RMAN When performing a consistent backup (also known as cold or offline backup) with Recovery Manager, it will backup the datafiles and generate a backup controlfile, the online redo logs are never backed up by RMAN. Hence, after a full database restore, the database has to be opened with RESETLOGS, because online redo logs are not available. The OPEN RESETLOGS command will create the online redo logs based on information from the … [Read more...] about Oracle RMAN – Restore and Recovery of a Noarchivelog Database
Understanding OS load average and run queue/blocked queue in terms of CPU utilization in Linux
When it comes to troubleshooting a performance issue on Linux, it is very important to know the basics of various command outputs such as uptime, vmstat. In this post, we will try to understand the load averages and run queue/blocked queue in terms of CPU utilization. First, let's understand what is Load Average: Load average is the number of jobs in the run queue (state R) or waiting for disk I/O (state D) averaged over 1, 5, and 15 minutes. Example output from uptime/top command: # … [Read more...] about Understanding OS load average and run queue/blocked queue in terms of CPU utilization in Linux
How to Create a Custom Log File Rotation by logrotate in Linux
In this example case /var/log/secure.log will be rotated daily and if the log file size exceeds 100mb rotate process will start. 1. By default system rotates all major OS logs by checking syslog file located in /etc/logrotate.d/ # cat /etc/logrotate.d/syslog /var/log/cron /var/log/maillog /var/log/messages /var/log/secure /var/log/spooler { sharedscripts postrotate /bin/kill -HUP 'cat /var/run/syslogd.pid 2> /dev/null' 2> /dev/null || true endscript } # 2. To add separate log … [Read more...] about How to Create a Custom Log File Rotation by logrotate in Linux
How to Move User datafiles between ASM Diskgroups using Incrementally Updated Backups
So the task here is to move user datafiles (not system or sysaux datafiles) between ASM diskgroups using the incrementally updated backups. The high-level steps are: Take level 0 datafile copy as a base to the new Diskgroup. This copy has either a system-defined or user-defined tag. Periodically take level 1 differential backups created with the same tag as the level 0 datafile copy. Use BACKUP FOR RECOVER OF COPY command so that an incremental backup is created containing only blocks … [Read more...] about How to Move User datafiles between ASM Diskgroups using Incrementally Updated Backups
Oracle Database – How to Rename a Datafile with Special Characters Created by Mistake
Question: We have mistakenly create a datafile with special charatcers. Also we get error ORA-01516 when we try to rename it using the normal method: sql> alter database rename file 'old_file_name' to 'new_file_name'; The Solution 1. Bring the Tablespace offline. sql> alter tablespace [tablespace name] offline; 2. Copy/Move the File at the OS level specifying the correct file name. 3. If there is no special character then the solution is: sql> alter database rename file … [Read more...] about Oracle Database – How to Rename a Datafile with Special Characters Created by Mistake
Oracle Database – How to Recover from a Lost or Deleted Datafile with Different Scenarios
This post explains the various scenarios for ORA-01157 and how to avoid them. How to Recover from a Lost Datafile in Different Scenarios In the event of a lost datafile or when the file cannot be accessed an ORA-01157 is reported followed by ORA-01110. Besides this, you may encounter error ORA-07360 : sfifi: stat error, unable to obtain information about file. A DBWR trace file is also generated in the background_dump_dest directory. If an attempt is made to shutdown the database normal or … [Read more...] about Oracle Database – How to Recover from a Lost or Deleted Datafile with Different Scenarios
Oracle Database – How to recover from a lost datafile with no backup
Pre-requisites You have inadvertantly lost a datafile at the OS level and there are no current backups. You are in archivelog mode. You have ALL Archivelogs available since the datafile was created initially (creation date). ORA-1110, lost datafile, file not found. The Solution Since there are no backups, the database cannot be opened without this file unless dropped and the tablespace dropped. If this is an important file and tablespace, this is not a valid option. These files have to … [Read more...] about Oracle Database – How to recover from a lost datafile with no backup
Troubleshooting Common ORA-1157 Errors (cannot identify/lock data file)
Oracle Error: ORA-1157 An ORA-01157 is issued whenever Oracle attempts to access a file but cannot find or lock the file. Error Explanation: 01157, 00000, "cannot identify/lock data file %s - see DBWR trace file" Cause: The background process was either unable to find one of the data files or failed to lock it because the file was already in use. The database will prohibit access to this file but other files will be unaffected. However, the first instance to open the database will … [Read more...] about Troubleshooting Common ORA-1157 Errors (cannot identify/lock data file)