Grown Sector Media Errors
How They Occur
Grown sector media errors occur due to the following:
The drive itself can often repair these errors by recalculating lost
data from Error Correction Code (ECC) information stored within each
data sector on the drive.
The drive then remaps this damaged sector to an unused area of the drive to prevent data loss.
See Grown Sector Media Error Protection for information
about protection provided at the ServeRAID adapter level.
Note:Sector media errors, which affect only a small area of the surface
of the drive, may not be detected in seldom used files or in non-data areas of the disk.
These errors are only identified and corrected if a read or write request is made to data stored
within that location.
Data scrubbing forces all sectors in the logical drive to be accessed so
that sector media errors are detected by the drive.
Once detected, the drive's error recovery procedures are launched to repair these errors by
recalculating the lost data from the ECC information described above.
If the ECC information is not sufficient to recalculate the lost data, the
information may still be recovered if the drive is part of a RAID-5 or RAID-1 array.
RAID-5 and RAID-1 arrays can provide their own redundant
information (similar to the ECC data written on the drive itself), which
is stored on other drives in the array.
The ServeRAID adapter can recalculate the lost data and remap the bad sector.
Note: The act of synchronization executes data scrubbing.
Data scrubbing can be performed in the background while allowing concurrent user disk activity on
RAID-5 and RAID-1 logical drives.
Netfinity Manager 5.0 allows you to schedule synchronization automatically from either
the server or the remote manager.
Netfinity Manager 5.0 can be obtained at no additional charge by customers who
have ServerGuide, which is shipped with every IBM server.
If the customer has another type of scheduler, such as the AT scheduler, built
into Windows NT, or REXXWARE by Simware Corporation, the IBM PC
ServeRAID and ServeRAID II Adapter IPSSEND utility may be used to allow
the customer to schedule data scrubbing without Netfinity Manager
installed.
Refer to Automatic Data Scrubbing and Data Scrubbing Utilities
for the adapter and operating Utilities system compatibility matrix for these data scrubbing utilities.
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