C-Glossary
Write-back Cache a caching scheme that acknowledges the write request as complete before data is written to the final storage location. This methodology can improve the efficiency of write operations under favorable circumstances, but is at risk of data incoherencies in a system that is not protected from power fluctuations or failures.
Write-through Cache When a cache is operating in write-through mode, data written into the cache is also written to the destination secondary storage devices. Essentially write completion does not occur until the data is written to secondary storage. Thus the contents of the cache and the secondary storage are always consistent. The advantage is that the possibility of data corruption is greatly reduced. The disadvantage is that write-through operations are more time consuming
XOR Function All RAID arrays (with the exception of RAID 0, RAID 1 and RAID 10) require parity to be calculated and written to the array in conjunction with data. Typically the parity is a simple XOR on the bytes comprising a stripe. This is a computationally intensive operation that many modern RAID controllers perform using a dedicated ASIC often referred to as a XOR-engine.
RAIDBank5 Owner’s Manual | 45 |