You first need to find out the physical path to the DVD drive by running:
sudo lsblk -f
The output can look like this:
NAME FSTYPE LABEL UUID MOUNTPOINT
sr0 iso9660 XenServer Tools 2017-02-14-21-45-52-00
xvda
├─xvda1 ext2 b874af3a-24ec-454f-a802-0fee2945e388 /boot
├─xvda2
└─xvda5 LVM2_member LOmK2X-RYRD-GR8s-Guzv-kXFN-e3Y8-gSVdgM
├─nginx–vg-root ext4 2dd0c496-ea05-4027-bf90-84ceb94d2f3a /
└─nginx–vg-swap_1 swap 77064139-1d50-4344-ade7-dacec1e62c9b [SWAP]
#As you can see, I already “inserted” the Xen Tools disk and the drive has /dev/sr0 physical path. Then, you need to create a directory where the drive will be mounted and then mount it:
$ sudo mkdir /mnt/dvd
$ sudo mount /dev/sr0 /mnt/dvd
mount: /dev/sr0 is write-protected, mounting read-only
#Then, run the installer
cd /mnt/dvd/Linux
sudo ./install.sh