Recently I added a new storage disk to a cloud server. The issue is that this disk might not always be available at boot time. There is an easy fix for this kind of problems. The nobootwait mount option (like it would show in a fstab entry):
/dev/xvdd1 /storage ext4 defaults,nobootwait 0 0
Note that the fsck order of 0 already ensures that fsck will not hold the boot process by complaining the disk is missing.
This is what I did, then I tried to mount my new attached disk:
mount: wrong fs type, bad option, bad superblock on /dev/xvdd1,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so
I checked dmesg and this is what it spitted out:
dmesg | grep xvdd1 | tail -n1
EXT4-fs (xvdd1): Unrecognized mount option "nobootwait" or missing value
I’ll be, CentOS never heard of it (surprise, surprise). I thought about nofailm but I was not sure it would do the trick.
This is what fstab(5) says about nobootwait
The mountall(8) program that mounts filesystem during boot also recognises additional options that the ordinary mount(8) tool does not. These are: bootwait which can be applied to remote filesystems mounted outside of /usr or /var, without which mountall(8) would not hold up the boot for these; nobootwait which can be applied to non-remote filesystems to explicitly instruct mountall(8) not to hold up the boot for them; optional which causes the entry to be ignored if the filesystem type is not known at boot time; and showthrough which permits a mountpoint to be mounted before its parent mountpoint (this latter should be used carefully, as it can cause boot hangs).
and this about nofail
nofail do not report errors for this device if it does not exist.
So I took the hackish route of adding noauto instead of nobootwait. This way the disk is not even mounted at boot time, and so it can be missing and added a mount line in rc.local.
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.
/bin/mount /storage &
Let me know if you know or find a better way of doing this.