les@chinet.chi.il.us (Leslie Mikesell) (11/07/90)
Is it safe for one process to from a file while another one is writing (i.e. can small write()s be considered atomic)? The only scenario where I would anticipate a problem is where the write() spans a block (the writes are small, but not necessarily alligned with disk blocks). If the second buffer block needed for the write() to complete needs to be read from disk, does the entire operation block or might the first block affected be written to the disk buffer and another process allowed to run while the disk operation completes? This is under SysVr3.2. If concurrent operations are not safe, would alligning the data so writes never span disk blocks help? If I need a locking mechanism, what would have the least impact on the writing process? Les Mikesell les@chinet.chi.il.us