hi, guys: when I read the filestore.cc, I find the ceph use crc the check the data. Why should check the data? In my knowledge, the disk has 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 sector header, the data area and the 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? Thanks -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20140904/a0bf4dc0/attachment.htm>