Don't merge now, I need to investigate why these mirrors are unavailable.

Thanks for PR,most of the reasons for being unavailable are that schools are on vacation and the server will be shut down to save power,so don’t remove them just yet(hit scau njupt).
dgut stopped serving last year.

the reasons for being unavailable are that schools are on vacation and the server will be shut down to save power,so don’t remove them just yet(hit scau njupt)

This reasoning is unacceptable in my opinion and a highly available SLA should be required.

They also mirror other things, such as archlinux, so why don't the maintainers of archlinux remove it from the mirror list?

China's mirror sites currently have the largest number of mirror sites in the mirror list, so we don't need to worry about SLA.

why don't the maintainers of archlinux remove it from the mirror list?

That's the point, the DGUT mirror removal for archlinux was submitted by me. Even though it has stopped working for a long time, the maintainer will not remove it voluntarily.

Because DGUT has stopped serving, there is no announcement from other mirror sites.

https://gitlab.archlinux.org/archlinux/rfcs/-/merge_requests/29

https://gitlab.archlinux.org/archlinux/rfcs/-/merge_requests/29

The current solution is to reduce their WEIGHT, and then wait until the National Day to test again to see if there are any missing mirrors.

In addition, it is impossible for us to monitor the status of those mirrors in real time like archlinux, which will increase the load on their servers.
While there are many third-party websites that can be used to monitor these mirrors, I don't feel it's necessary. The user will always get a mirror available.