Why should i use lvscan --readonly and not lvscan?

Hi, I'm trying to finish my final project which is about LVM, and i cant really understand the objective/goal/purpose of this command "lvscan --readonly".

Any help is welcomed.

Is the man command malfunctioning on your system? From man lvscan:

--readonly
       Run  the command in a special read-only mode which will read on-
       disk metadata without needing to take any  locks.  This  can  be
       used  to  peek  inside  metadata used by a virtual machine image
       while the virtual machine is running. No attempt will be made to
       communicate with the device-mapper kernel driver, so this option
       is unable to report whether or not LVs are actually in use.

How is this not crystal clear? I mean, the text even includes a use case example.

Well, Im not a native english speaker, so i was hoping that someone will explained to me with less technical word`s so i could start to understand the --readonly command.

I'm not a native English speaker either. If you've already looked at various sources but found them hard to understand, please quote them or post a link, and ask specific questions about the terms and/or concepts you find difficult to understand.

For instance, which terms in the man page text would you like to have explained in greater detail?

But why would i want in a hypothethic case to use --readonly? What problem do i avoid by using it? That it's what i dont get. Why shoul i execute lvscan --readonly and not lvscan?

The man page post above gives you one use case where the --readonly would be preferred.

       disk metadata without needing to take any  locks.  This  can  be
       used  to  peek  inside  metadata used by a virtual machine image
       while the virtual machine is running.

Think what might happen if the lv is locked while the scan is running on a file system that is in use. Potential for data corruption and/or causing a system crash in the VM. Thus it would be a good time to use that option.

I suggest you ponder the text given and think deeply about why it is stated that way