I have two linux instances on amazon. Both of them have one disk device.
For test, I power off one instance (A) and attach its volume to the second one (B), as /dev/xvdf
Into this server, I can mount and use (B), for example as /mount/xvdf.
Now the weirdness : I reboot this server (B) : sometimes it starts and I see its volume as / and the (B) volume as /mount/xvdf.
Sometimes (B) starts ... and I have the (B) volume as / !
This is the output of 'dmesg | grep xvd' in this weird case :
[102029834.997373] blkfront: xvda1: barrier or flush: disabled; persistent grants: disabled; indirect descriptors: disabled;
[102029835.000238] blkfront: xvdf: barrier or flush: disabled; persistent grants: disabled; indirect descriptors: disabled;
[102029835.309885] EXT4-fs (xvdf): mounted filesystem with ordered data mode. Opts: (null)
[102029835.323719] EXT4-fs (xvdf): mounted filesystem with ordered data mode. Opts: (null)
[102029835.328251] dracut: Mounted root filesystem /dev/xvdf
[102029836.817661] EXT4-fs (xvdf): re-mounted. Opts: (null)
And this is 'cat /etc/fstab' ... of volume (B) mounted as / :
/ ext4 defaults,relatime 1 1 tmpfs
/dev/shm tmpfs defaults 0 0 devpts /dev/pts
devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults
0 0 proc /proc proc defaults 0 0
Is it possible I have a 'wrong' syntax in /etc/fstab so the system cannot discern which mount as / ?
How to fix this caos ?