Japan and China ping time observations
From Shanghai/area to Japan/Tokyo area.
OCN/NTT 215-96ms 124.102.42.x
OCN/NTT was quite disappointing as ping times were drastically different, between 215 and 96ms as mentioned.
Softbank (BBTECH) 52ms 60.106.165.x 60.69.227.x 219.101.163.x
Softbank consistently performed well with China.
So-net 42.8ms 118.238.215.x
So-net was the lowest ping we've seen to Japan.
Asahi.net 91.9ms 221.113.95.x (Chiba)........
mdadm can you downgrade the superblock?
Why would you want to downgrade the superblock? Old mdadm verisons like mdadm 2.5.6 only use the 0.90 superblock/metadata and new versions use 1,1.0,1.1 and 1.2 superblocks by default.
There are some annoying caveats with this, first of all the new superblocks (later than 0.90) CANNOT be read by GRUB, so you won't even be able to install GRUB. Even worse, old versions of mdadm CANNOT automatically detect arrays even if they were created with a new version of mdadm with th........