check the number of discs

vicibox7:~ # lsblk
NAME   MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sr0     11:0    1  580M  0 rom
vda    254:0    0   45G  0 disk
├─vda1 254:1    0    4G  0 part [SWAP]
├─vda2 254:2    0    4G  0 part [SWAP]
└─vda3 254:3    0   37G  0 part /


The disks are generally in the form of /dev/sdx and partitions /dev/sdxn, where x is a letter and n is a number (so sda is the first physical disk and sda1 is the first partition on that disk).