It can often improve performance and memory latency and usually only has a minor CPU performance impact as it trades cycles waiting for memory for cycles decompressing memory. It is usually decent even on low power embedded devices.

There are a few edge cases where ZRam is not great. If your data is already compressed or encrypted copying it around in memory is much more expensive. It’s also harder to tell exactly how much data can be loaded into the “free” memory. It’s also a bit slower for serialized memory access in large data sets if the compression ratio is low.

Right image, but under those each one below would also be wearing large pants covering each side of the subtree.

If filesystem UUIDs are IP equivalents. Then device paths are MAC addresses. FS labels are DNS. Device mapper entries are service discovery.

“Invalid” or “unparseable” are more understandable descriptors in normal language. I don’t think I ever heard of garbage/junk being used for that in language theory but it may be domain specific usage.

It can still have issues with potential attacks that would redirect your client to a system outside of the VPN. It would prevent MitM but not complete replacement.

Likely you needed to include the intermediate cert chain. Let’s encrypt sets that up automatically so it’s quite a bit easier to get right.

Initrd contains the systemd binary and enough libraries, services, and kernel modules to get booted this far. The system failed at switch root which is where the real root disk is mounted. Initrd can contain as much or as little as needed to get a working system which can be a lot of you are using a network filesystem as a root for instance.

The underutilized post pre increment operator.