Exadata - Disk scrubbing
Ahmet Duru?z
Senior Oracle , PostgreSQL , MySQL DBA | Instructor | Exadata Administrator | Oracle ACE ??
Disk scrubbing exists on Exadata cell nodes to automatically repair bad sectors of the disk when the system is idle, without sacrificing system performance.?It tries to repair bad sectors on the disk by working at certain periods when the disks are idle.?If too much bad area is starting to appear on the disc, you can increase the scrubbing interval.
We can access information about disk scrubbing activity with the following commands.
Detection of whether Disk scrub activity is active on the Exadata cell node:
CellCLI> list cell attributes name,hardDiskScrubInterval
exa1celadm01 biweekly
Detection of whether the Harddisk Scrub process has started on the Exadata Cell node:
If the $CELLTRACE/alert.log file on Cellnode contains the following information, the process has been started and completed.
The cell alert log file will contain statements as follows.
=> When scrubbing starts:
Begin scrubbing CellDisk:CD_05_exa1celadm01.
=> When scrubbing is finished:
Finished scrubbing CellDisk:CD_05_exa1celadm01, scrubbed blocks (1MB):1906336, found bad blocks:0
In addition, when the griddisks are checked, if there is an active scrub process, the status of the griddisk will be seen as “active – scrub resilvering working”.?
Determining the scheduling time of the Harddisk Scrub process:
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CellCLI> list cell attributes name,hardDiskScrubInterval
exa1celadm01 biweekly
NOTE : biweekly is the default value and means biweekly.?You can also set it as daily or weekly if you wish.
Closing the Harddisk Scrub process:
CellCLI> alter cell hardDiskScrubInterval=none
Cell exa1celadm01 successfully altered
Changing the running frequency of the Harddisk Scrub process:
Daily :
CellCLI> alter cell hardDiskScrubInterval=daily
Cell exa1celadm01 successfully altered
weekly :
CellCLI> alter cell hardDiskScrubInterval=weekly
Cell exa1celadm01 successfully altered
Every two weeks:
CellCLI> alter cell hardDiskScrubInterval=biweekly
Cell exa1celadm01 successfully altered
Ensuring that the Harddisk Scrub process starts at a specific date and time:
CellCLI> alter cell hardDiskScrubStartTime='2018-12-12T21:30:22+03:00'
Cell exa1celadm01 successfully altered
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NOTE : At the end of the time, the timezone value should also be given.?That's what +03:00 above is for.