How do you fsck or change /etc/fstab when root is read-only?

I’m upgrading a server again and we replaced the RAID array with SSDs (it’s a 10x IOPS improvement; so worth it). But booting the system it fails to start because the old UUID listed in /etc/fstab is no longer available.

Screen Shot 2016-01-27 at 6.12.27 PM

That “Unable to resolve” message caused the filesystem check to fail. Linux drops into a shell with the root volume loaded but in read-only mode.

To fix this I needed to change /etc/fstab to remove the offending entry. But I couldn’t write to the file system.

The obvious solution (with help from our hosting partner) is to remount the root partition as read-write:

mount -o remount,rw /

Now, I can edit /etc/fstab, comment out the offending line, exit and the system will reboot into a running server.

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s