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Exadata – Disk scrubbing feature

Disk scrubbing is available on Exadata cell nodes to automatically repair bad sectors on the disk when the system is idle, without compromising system performance. It works periodically when the disks are idle, to repair bad sectors on the disk. If too much bad space is forming on the disk, you can increase the scrubbing interval.

We can access information about disk scrubbing activity with the following commands.

Determining whether Disk scrub activity is active on the Exadata cell node:

CellCLI> list cell attributes name,hardDiskScrubInterval
exa1celadm01 biweekly

Determining whether the Harddisk Scrub process has started on the Exadata Cell node:

If the $CELLTRACE/alert.log file on the Cellnode contains the following information, the process has started and completed.

The cell alert log file will contain statements such as the following.

=>When scrubbing starts:

Begin scrubbing CellDisk:CD_05_exa1celadm01.

=>When scrubbing is over:

Finished scrubbing CellDisk:CD_05_exa1celadm01, scrubbed blocks (1MB):1906336, found bad blocks:0

Additionally, when griddisks are checked, if there is an active scrub process on them, the status of the griddisk will be seen as “active – scrub resilvering working”. 

Determining the scheduling time of the hard disk scrub process:

CellCLI> list cell attributes name,hardDiskScrubInterval
exa1celadm01 biweekly

NOTE: biweekly is the default value and means once every two weeks. You can also set it as daily or weekly if you wish.

To close the Hard Disk Scrub process:

CellCLI> alter cell hardDiskScrubInterval=none
Cell exa1celadm01 successfully altered

Changing the frequency of the Hard Disk 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 Hard Disk Scrub process starts at a specific date and time:

CellCLI> alter cell hardDiskScrubStartTime='2018-12-12T21:30:22+03:00'
Cell exa1celadm01 successfully altered

 

NOTE: The timezone value must also be given at the end of the time. This is what the +03:00 above is for.

 

 

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