linux-9f6u:~ # zypper in rzsz
Loading repository data...
Reading installed packages...
Resolving package dependencies...

The following NEW package is going to be installed:
  rzsz

1 new package to install.
Overall download size: 98.2 KiB. Already cached: 0 B. After the operation, additional 258.8 KiB will be used.
Continue? [y/n/...? shows all options] (y): y
Retrieving package rzsz-0.12.20-999.19.x86_64                                                        (1/1),  98.2 KiB (258.8 KiB unpacked)
Failed to mount cd:///?devices=/dev/disk/by-id/ata-VMware_Virtual_SATA_CDRW_Drive_01000000000000000001 on /var/adm/mount/AP_0xzxJxmD: Mounting media failed (mount: no medium found on /dev/sr1)

Please insert medium [SLES12-SP3-12.3-0] #1 and type 'y' to continue or 'n' to cancel the operation. [yes/no] (no): y
Failed to mount cd:///?devices=/dev/disk/by-id/ata-VMware_Virtual_SATA_CDRW_Drive_01000000000000000001 on /var/adm/mount/AP_0xluokDi: Mounting media failed (mount: no medium found on /dev/sr1)

Please insert medium [SLES12-SP3-12.3-0] #1 and type 'y' to continue or 'n' to cancel the operation. [yes/no] (no): y
Failed to mount cd:///?devices=/dev/disk/by-id/ata-VMware_Virtual_SATA_CDRW_Drive_01000000000000000001 on /var/adm/mount/AP_0x4HC9c0: Mounting media failed (mount: no medium found on /dev/sr1)

Please insert medium [SLES12-SP3-12.3-0] #1 and type 'y' to continue or 'n' to cancel the operation. [yes/no] (no): q^Clinux-9f6u:~ # 

设置如下，注意提示的sr1，对应的CD/DVD2: