Bruce Momjian <[EMAIL PROTECTED]> writes: >> Oh. I thought we'd agreed that a CRC on each stored disk block would >> be a good idea as well. I take it you didn't do that. > No, I thought we agreed disk block CRC was way overkill. If the CRC on > the WAL log checks for errors that are not checked anywhere else, then > fine, but I thought disk CRC would just duplicate the I/O subsystem/disk > checks. A disk-block CRC would detect partially written blocks (ie, power drops after disk has written M of the N sectors in a block). The disk's own checks will NOT consider this condition a failure. I'm not convinced that WAL will reliably detect it either (Vadim?). Certainly WAL will not help for corruption caused by external agents, away from any updates that are actually being performed/logged. regards, tom lane