Some complexity levels not mentioned in the article: * Consistency groups. The article kinda almost gets there, but stops right before it realizes there's a p

Some complexity levels not mentioned in the article: * Consistency groups. The article kinda almost gets there, but stops right before it realizes there's a problem. If you have multiple programs accessing the storage, s.a. a database (that you are snapshotting) and the application using the database, then you are risking an inconsistent snapshot when the database state you wrote is ahead or behind the application state. You need a mechanism to freeze all I/O beside the snapshot in order to ensure that the snapshot data is useful. * ACLs. And similar external mapping to the storage being used, eg. what if the users come from an LDAP server? Similar problem with symlinks coming from/going to ouitside the snapshot. * Sparse file support. Let's say you have a few VM images in your snapshot: if your tool doesn't support sparse files, it will likely greatly inflate the image sizes. Bottom line, either use the product's own snapshot functionality (ZFS has those), or switch to the product that does.