[email protected]: > > - You have the structural consistency of the file system itself > (directory structure, partial writes to files, superblock, etc). > LVM and other snapshotters help you with that.
I was always under the impression that an LVM snapshot is not better than an unclean filesystem, like for example after a power loss. But this 20 year old document proved me wrong: https://tldp.org/HOWTO/LVM-HOWTO/snapshotintro.html | This facility does require that the snapshot be made at a time when | the data on the logical volume is in a consistent state - the VFS-lock | patch for LVM1 makes sure that some filesystems do this automatically | when a snapshot is created, and many of the filesystems in the 2.6 | kernel do this automatically when a snapshot is created without | patching. I did not current information on this explicitly, but apparently nowadays you can expect that "many filesystems" actually support being snapshotted by LVM and make sure that the state on disk is clean when an LVM snapshot is created. > - Then you have the consistency of the data in the file system itself > (imagine a backing file for a relational database, say PostgreSQL, > for example). For that, only the applications themselves can help > you, no amount of LVM or snapshotting will, because it knows nothing > about the applications's inner structures. This is also true. For home/office machines a simple file-based backup solution is usually sufficent. For servers that might not be the case and you should rely on application-specific backup tools. I have never felt the urge to backup a partition layout or do a "whole disk backup" in one step. I am using LVM on all of my machines for flexibility (filesystem resizing) and convenience (disk migration possibilities). J. -- My medicine shelf is my altar. [Agree] [Disagree] <http://archive.slowlydownward.com/NODATA/data_enter2.html>
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