hairong Kuang wrote:
I agree that it is too expensive to call checkDir for every I/O operation.
But checkDir is usefully in the case that a disk suddenly became only
readable. We saw this happened before. But we definitely should revisit it
since now a datanode is able to manage multiple data directories and each
data directory maitain multiple levels.
Hairong
For hard disks and native filesystems any one of many many things can go
wrong. We can not realistically check all and I don't think this
perticular failure is any more probable than others. This should be
handled just like any other issue we handle at datanode. DFS is designed
to deal with flacky datanodes.
Raghu,.
