On Thu, 4 Sep 2014 16:31:12 +0800 ??? wrote: > hi, everyone: > > when I read the filestore.cc, I find the ceph use crc the check the > data. Why should check the data? > It should do even more, it should also do checksums for all replicas: > In my knowledge, the disk has error-correcting code > <http://en.wikipedia.org/wiki/Error-correcting_code> (ECC) for each > sector. Looking at wiki: http://en.wikipedia.org/wiki/Disk_sector, "In > disk drives, each physical sector is made up of three basic parts, the > sectorheader <http://en.wikipedia.org/wiki/Header_(computing)>, the data > area and the error-correcting > code <http://en.wikipedia.org/wiki/Error-correcting_code> (ECC)". So if > the data is not correct. the disk can recovery it or return i/o error. > > Does anyone can explain it? > http://en.wikipedia.org/wiki/Data_corruption#Silent_data_corruption -- Christian Balzer Network/Systems Engineer chibi at gol.com Global OnLine Japan/Fusion Communications http://www.gol.com/
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