Data Scrubbing
Data Scrubbing
Data Scrubbing Another way to force discovery and correction of
sector media errors is data scrubbing .
Array synchronization reads the data and parity blocks from all the
disks and checks that the parity correctly matches the data block
information. If the logical drive was synchronized upon configuration,
the parity information matches the data. The synchronization procedure
is, therefore, used for data scrubbing. The advantage to this procedure,
when used in addition to tape backups, is that data scrubbing examines
unallocated sectors of the drive, in addition to those that have been
allocated, that is, data areas protected by a tape backup. If any sector
media errors are found during this process, they are corrected at the
disk level using disk ECC information, if possible, or at the array
level using RAID parity information, if necessary.
Automatic Data Scrubbing and Data Scrubbing Utilities: ServeRAID
II, 3H, and 3L Adapters allow RAID-5 and RAID-1 logical drives to be
data scrubbed in the background via firmware. This feature is available
using the following firmware levels available from:
http://www.us.pc.ibm.com/files.html
Note:
You do not need to synchronize RAID level-0 or 1 logical drives
before storing data.
Data scrubbing continuously reads all sectors of RAID-1 and RAID-5
logical drives in the background while the system is running. If a
defective sector is found, it is automatically repaired. As a result of
this feature, you no longer have to synchronize RAID level-1 and RAID
level-5 logical drives on a weekly basis.
You must synchronize all RAID level-5 logical drives before storing
data.
The IBM PC ServeRAID Adapter allows RAID-5 and RAID-1 logical drives to
be data scrubbed via the synchronization utility by taking the server
offline and running the IBM ServeRAID Configuration Diskette. Array
synchronization may take several hours, depending on the size of the
logical drive. The ServeRAID adapter provides various utilities to
provide the customer with data scrubbing flexibility.
The table below shows the utilities available for the IBM PC ServeRAID
Adapter in specific operating system environments. With the exception of
Netfinity Manager, the utilities below can be downloaded from
http://www.us.pc.ibm.com/files.html
The section following the table discusses the benefits of the
utilities and how to obtain, install and use them.
| Windows NT |
Netware |
OS/2 |
SCO |
Netfinity Manager 5 and above IBM ServeRAID Configuration
Diskette
IPSSEND
ServeRAID Administration and Monitoring Utility |
Netfinity Manager 5 and above IBM ServeRAID Configuration
Diskette
IPSSEND
ServeRAID Administration and Monitoring Utility |
Netfinity Manager 5 and above IBM ServeRAID Configuration Diskette
IPSSEND
ServeRAID Administration and Monitoring Utility |
IBM ServeRAID Configuration Diskette
IPSSEND
ServeRAID
Administration and Monitoring Utility |
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