Method for logical unit creation with immediate availability in a raid storage environment

A RAID storage system comprising:

• a logical unit creator to define a RAID level 5 logical unit in said storage system;
• a logical unit initializer to initialize said logical unit by assuring consistency of redundancy information and data in said logical unit, save checkpoint data periodically during initialization indicative of progress of the initialization, interrupt the initialization, and resume the initialization using said checkpoint data;
• and
• an I/O request processor to process I/O requests directed to said logical unit from attached host systems, wherein said logical unit initializer is operable in parallel with said I/O request processor, said I/O request processor further configured for determining whether an I/O request to be processed includes access to storage space of said logical unit below said boundary parameter value, processing said I/O request normally in response to determining that said I/O request does not include access to storage space below said boundary parameter value, processing said I/O request in a manner so as to assure integrity of redundancy information associated with data of said I/O request in response to determining that said I/O request requires access to storage space below said boundary parameter value, requeuing said I/O request for later processing in response to a determination that the data to be accessed crosses said boundary parameter value.

A storage controller in a RAID storage system for enabling immediate access to said RAID storage system, said storage controller comprising:

• means for creating a RAID level 5 logical unit within said RAID storage system;
• means for initializing said logical unit in response to creation of said logical unit;
• and
• means for processing I/O requests directed to said logical unit in parallel with operation of said means for initializing, wherein the means of initializing comprises
• means for maintaining a boundary parameter value indicative of the progress of the initialization of said logical unit wherein said boundary parameter value indicates a physical position in said logical unit above which initialization is complete and below which initialization is incomplete,
• means for saving checkpoint data periodically during processing of the initialization indicative of progress of the initialization,
• means for interrupting processing of the means for initializing, and
• means for resuming the initialization using said checkpoint data, and the means for processing comprises
• means for determining whether an I/O request to be processed includes access to storage space of said logical unit below said boundary parameter value,
• means for processing said I/O request normally in response to determining that said I/O request does not include access to storage space below said boundary parameter value,
• means for processing said I/O request in a manner so as to assure integrity of redundancy information associated with data of said I/O request in response to determining that said I/O request requires access to storage space below said boundary parameter value,
• means for requeuing said I/O request for later processing in response to a determination that the data to be accessed crosses said boundary parameter value.