Hi, I am a new guy for a Linux programming. I got a question for a software RAID-5 parity calculation. If we suppose for data block D1, D2, D3, D4 with a parity block P, When some data block is changed, P will be changed. I am not so clear how does Linux md handle the parity re calculating, when data changed . Suppose there will be three cases, 1. sequential write, is that get new P' directly with new data D1', D2', D3' and D4' or need read D1-4 out from disk doing the normal operation. 2. if we changed there blocks, D1',D2' and D3', does md read D1, D2, D3 out to rebuild P or just read D4 out from disk and rebuild P with D1', D2', D3' and D4. 3. is the simple case, just change one block. Thanks a lot, if some can help me get understand it. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
