[SOLVED -> workaround] CentOS: very slow system boot / sometimes hangs entirely

[TrevorH]

You can probably shoot the penguins by appending nomodeset to the kernel command line but if your video drivers depend on modesetting (and most do) then it will break those.

[socrates]

Well, TrevorH, avij -- it was indeed a wild-goose chase

Turns out, it was after all related to USB and avij's suggestion to look for a solution in the BIOS was the key!

Since the board has a very limited AMI-Bios there is not much to configure, sadly. But when I completely disable USB, the system boots like a rocket (in comparion, of course). Once the boot has completed I can use by USB keyboard, only BIOS and grub are inaccessible. But for those rare scenarios I happen to have a PS/2 keyboard lying around.

Thank you very much for your support, guys!

[avij]

OK, glad to hear. This may be caused by either a) faulty hardware, b) buggy BIOS or c) buggy CentOS kernel. You may want to retest this once 7.5 is released (no, nobody outside Red Hat has an idea of when that will be, and RH people aren't allowed to tell).