How do zfs snapshots work

Otherwise, you may end up with some extremely large snapshots. One useful feature of ZFS snapshots is the ability to mount them as read-only to pull out certain files or rollback an entire filesystem to the last time a snapshot was created.

ZFS snapshots can greatly help system admins with accident-prone users who may misplace or accidentally delete important files.

Although ZFS snapshots serve their purpose well they in no way replace an adequate backup solution. Companies need to be able to recover from lost data with minimal or no downtime.

This is why snapshots can be a godsend, but in case of a large scale disaster or damage of the source data, the snapshot may become lost. I know I said it before but I want to reiterate snapshots are not adequate backup. Mission-critical data should always be backed up to a separate location.

ZFS has a option to backup or move the snapshots. This is possible with the send and receive commands. ZFS send You can save the output stream generated by the send command to a file by redirection. ZFS receive Similar to send you can recieve a snapshot from the file we just created. ZFS clones as contrary to ZFS snapshots are writable copy of the file system with initial content same as the file system.

Perhaps in a 0. Didn't find any info about the date of the article, I'm assuming it's quite old but I just wanted to add something. At the mounting point of each dataset, there's a.

They are read-only, of course. Note that you WON'T see this folder, even with ls -a. You can cd into it though. Yup, you have to know it's there, but it is. ZFS pools are used to store datasets. It's the datasets that get mounted - think of a dataset like an LVM volume, or a partition with a traditional filesystem on it.

So with ZFS first you create a pool which consists of one or more vdevd a vdev can be a single disk, a mirror, or a raid of disks - personally I have several machines running multiple mirror vdevs in a single pool. Then you create datasets on the pool, giving each dataset a mountpoint. Sorry to say but you have not made a back up of your data, you have made a back up of a snapshot, a snapshot is only the data that has changed in the original set sinds the snapshot.

If you loose your original data, a snap shot will not save you!! This mistake is so widespread that i cant find a good tutorila in howto propperly Back up the original dataset anywhere on internet, even Oracle thinks the original dataset will never die What if you create a datapool and then before putting it to use you create a snapshot?

Would this be enough to have a copy of your data right? This feature is only available to subscribers. Get your subscription here. Log in or Sign up. Suggested articles. This article Didnt bother reading it beyond first two line.