|
|
|
For the IBM ServeRAID and ServeRAlD II Adapters, Synchronization and Initialization is
required befbre installing an operating system or storing any customer data on a RAID-5 array
for data integrity and to provide data protection. The RAID-5 arrays write data out to drives in
stripe units. The size of the stripe unit can be configured to 8KB, l6KB, 32KB, or 64KB.
Synchronization reads all the data bits in each stripe unit, calculates the parity for that data,
compares the calculated parity with the existing parity for all stripe units in the array, and updates
the existing parity if inconsistent. Initialization writes zeroes out to the logical drive. Operating
systems may not install properly if the first few sectors are not set to zero (approximately the first
32 sectors).
After the user creates the array, he or she must create a logical drive. Logical drives are different
from physical drives. Physical drives are the individual disk drives that are inside your machine.
The logical drive is the drive that the array controller shows the operating system. A logical
drive is spread across multiple physical drives. All RAID-5 logical drives must be synchronized
after being defined before storing any data. The IBM ServeRAlD Configuration Utility does not
force the user to synchronize the logical drive when defined in order to provide the customer the
flexibility to define multiple logical drives and then synchronize them in one step. Once the
array has been synchronized, the RAID-5 parity will remain synchronized until the logical drive
is redefined.
If data is stored before synchronizing a RAID-5 array with the IBM ServeRAID and
ServeRAlD II Adapters, this data is not protected: the corresponding parity for this data
may not be correct. If you do not know whether the RAID-5 logical drives have ever been
synchronized, then you can use the IBM ServeRAID SynchVerify/Update Diskette to determine
whether the RAID-5 logical drives are synchronized or not. The SynchVerify/Update Diskette
consists of the following two tools:
Please see the LEGAL - Trademark notice.
Feel free - send a 
for any BUG on this page found - Thank you.