VXA Tape Format Offers Advanced Error Correction Functionality

Computers & TechnologyTechnology

  • Author Jessica Mcintosh
  • Published February 13, 2010
  • Word count 537

In VXA backup tape format, the tape drive reads and writes the information in "data packet" form. Before recording information onto the VXA data tape, the data which comprises of long strings is then split into smaller units known as the "data packets". Afterwards the VXA tape drive writes the data onto the data cartridge. Another new mechanism called "read after write" assures data precision and integrity. This new mechanism has been designed to ensure long term durability and exceptional reliability of VXA tape. 64 bytes make one data packet. Unique address, ECC (error correction code), synchronization marker and CRC (cyclical redundancy check) are assigned to each data packet.

The VXA tape drive features an innovative buffer segment that reads and records these data packets. 387 data packets are included in each of the data track. All of the 4 tape heads take part in the read operation. After scanning the tape media the VXA tape drive read these data packets into the tape drive’s buffer segment. The unique addresses assigned to the data packets is read by the VXA data buffer which then reunites these data packets in the correct form. The order in which these data packets are received by the buffer does not affect the data integrity as the VXA data buffer rearranges the packets according to their assigned addresses. During the first pass, the VXA buffer retains the correctly read data packets. The data packets that have been missing during the first pass are then read through the subsequent passes. Afterwards the missing data packets are added to the strings in order to complete all of the information. After the completion of data, it is then sent to the host system. This recording technique used in VXA is similar to that used in re-writable CDs, networking and internet.

New correction system for errors has been engineered for the VXA tape format that comprises of 4 levels. This error correction process completes its operation in 2 phases. In the first step of error correction, the Reed-Solomon ECC is added to each of the packet that has the capability to remove the typical errors that can result from noise or shifting of phases. Then in the next phase, the VXA tape buffer forms a matrix of the data packets that have been collected by the buffer.

This matrix of data packets incorporates a 3 dimensional Reed-Solomon ECC that is composed of Y-axis, Diagonal and X-axis ECC. This error correction system of VXA has the capability to correct maximum of 2 lost packets in each diagonal, 2 in each column and 2 in each row of the buffer array. Therefore this efficient error correction mechanism minimizes the error rate to 1x10-17. This error rate can be easily be understood by an example that it is equivalent to finding a single grain in a football stadium that has been completely filled with sand. VSO (variable speed operation) is a highly efficient mechanism introduced in VXA data tape media that improves the performance level and data integrity. Variable speed technique has been developed to enable the VXA drive to alter the tape’s speed so that it can be matched with host’s transfer rate. VSO functionality ensures superior data reliability and cost effective operations.

VXA tape format is very economical, offers faster transfer rates and superior data reliability. VXA-X and VXA-V are the two versions of VXA tape format. Tape4backup offers lifetime warranty on all IBM and Exabyte VXA tape cartridges.

Jessica McIntosh

34972 Newark Blvd, # 501, Newark CA 94560

Tel: 888-491-4949

Fax: 888-449-5050

Email: jessica@tape4backup.com

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