Mount /etc/fstab – How to Mount at Startup

You could try using:

fuser -c /dev/dsk/c0t0d0s3

(or the rdsk equivalent) to see if there are any processes using that specific raw disk. Since this is Solaris 10, I have to ask does that partition contain any SVM or ZPOOL data that might be causing it to be used?

I know this was already basically suggested, but I didn't see the -c, so also try:

fuser -c /data

You can copy the lines started with /dev/sd** from mtab (/etc/mtab) and paste them in to a new text file and change /dev/sd** with UUID or LABEL. For example from your config:

use

UUID="3fc55e0f-a9b3-4229-9e76-ca95b4825a40" / ext4 rw,errors=remount-ro 0 0

instead

/dev/sda1 / ext4 rw,errors=remount-ro 0 0

The line above also works, but UUID is the new standart and if your grub configured with UUID, it might can't understand which partition is what.

if partition has Label you can use the LABEL instead UUID, for example:

LABEL="Files_Server_Int" /media/Files_Server ext4 rw 0 0

IMO copy your mtab to a new file and remove the lines started with "none" and change the /dev/sd** part with blkid output equivelants. If UUID exist, use the UUID instead of /dev/sd**. If LABEL exist use the LABEL instead of UUID.

Do not remove anything else except "none" lines. Save the file, change the file name to fstab and copy in to /etc.

Finally add lines for swap if any (if you forget this, your system will boot but you might have zero swap space or swap file will be generated at root (/) depending of OS default configuration.). e.g. in your case note that blkid prints this line:

/dev/sda5: UUID="718e611d-b8a3-4f02-a0cc-b3025d8db54d" TYPE="swap" 

so you need this line in fstab:

UUID=718e611d-b8a3-4f02-a0cc-b3025d8db54d none  swap sw   0   0

This might help to restore your fstab.