Use lshw -xml to find the disk details

disks_lshw.py

#!/usr/bin/env python                                                                                                                                                                                                                        
# Parse disk:* from lshw -xml                                                                                                                                                                                                                

"""
Sample Output:

ATA Disk Hitachi HDS72105 /dev/sda
Disk Space:  500107862016
Sector size:  512

ATA Disk Hitachi HDS72105 /dev/sdb
Disk Space:  500107862016
Sector size:  512

Num disks 2
Total disk space 953880

"""

from lxml import etree
from subprocess import Popen,PIPE
inventory = Popen(['lshw', '-xml', '-numeric'], stdout=PIPE).communicate()[0]
inventory = etree.XML(inventory)

find_disks = etree.XPath(".//node[@class='disk']")

numdisks = 0
diskspace = 0
for disk in find_disks(inventory):
    # has to be a hard-disk
    if disk.find('size') is not None:
        numdisks = numdisks + 1
        diskspace = diskspace + int(disk.find('size').text)
        print disk.find('description').text, disk.find('product').text, disk.find('logicalname').text
        print 'Disk Space: ', disk.find('size').text
        print 'Sector size: ',disk.find('configuration/setting/[@id="sectorsize"]').get('value')
        print 

print 'Num disks', numdisks
print 'Total disk space', diskspace/(1024**2)