Sean P. Kane wrote 36 lines: > Does a snapshot create a copy of all the files in memory? Nope. And not in memory either. > Just the files that changed? Nope, LVM is filesystem-agnostic, and that would have to change that. More code, more errors, less usability. Additionally, what would you do with metadata, like used filesystem blocks and timestamps and filenames? Or with a 1 TB file where just 1 bit was changed? > Or just the file blocks or contents (i.e. diffs) that have > changed? Blocks of (default) 32Kb of raw disk. They are written to the snapshot. However, the tables of which blocks were written are kept in RAM, so a read request on the snapshot redirects only the unchanged blocks to the original (HD/CD) and gets the changed blocks out of the snapshot storage. > So, would the snapshot have to be the same size as the cdrom or > could it be smaller? MUCH smaller. Unless you insist on changing something in every 32KB block of the CDrom. -Wolfgang _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
