During the creation process of the esxi virtual machine, there are advanced options. The independent mode is not selected by default. So in what scenarios is the independent mode used? What is the performance impact?
Detailed introduction:
Independent persistent: All disk writes to the VM are actually written to disk (in the vmdk file). Even if you restart and restore the snapshot, the changes are retained. This mode provides the best performance. For example, if you create a new file test1 in a disk with independent persistence characteristics, and then create a snapshot firstsnapshot of the disk, the snapshot should only contain the test1 file. After creating the snapshot firstsnapshot, create a file test2 on the disk, and then restore the firstsnapshot snapshot. Under normal circumstances, after restoring the snapshot, the newly created test2 should not exist, but now due to the independent persistence feature, the result is that both test1 and test2 exist.
Independent nonpersistent: All changes made after the VM is started are undone when it is shut down. Modifications are written to a file that records all changes at the VM file system level. In this mode, restarting the VM means returning to the reference VM. Performance is not very good. If a standalone non-persistent disk is used, a successful attacker can destroy evidence of the compromised computer by shutting down or restarting the system. Without a persistent record of activity on a virtual machine, administrators may be unaware of the attack. Therefore, the use of independent non-persistent disks should be avoided. This feature is very similar to the restore wizard installed on computers in early Internet cafes and schools. Students can write any data on the machine when they get on the computer. Once the system is restarted, all operations done by the students will be restored to the state when they first got on the computer. , so that students in the next class can still use the same initial environment.
