> CoW is an efficiency gain. You're thinking of the optimization technique of CoW, as in what Linux does when spawning a new thread or forking a process. I'm t

> CoW is an efficiency gain. You're thinking of the optimization technique of CoW, as in what Linux does when spawning a new thread or forking a process. I'm talking about it in the context of only ever modifying copies of file system data and metadata blocks, for the purpose of ensuring file system integrity, even in the context of sudden power loss (EDIT: wrong link): https://www.qnx.com/developers/docs/8.0/com.qnx.doc.neutrino.sys_arch/topic/fsys_COW_filesystem.html https://www.qnx.com/developers/docs/8.0/com.qnx.doc.neutrino... If anything, ordinary file IO is likely to be slightly slower on a CoW file system, due to it always having to copy a block before said block can be modified and updating block pointers.