I'm about half way through, http://www.dedoimedo.com/computers/gparted.html
"GParted Partitioning Software - Full Tutorial", so at this point I have learned how to recognize drive letters (hd, sd), partition numbers (1-5+) and understand physical and logical with respect to partitions and extended partitions.
I have reconfirmed with an invoice and reading off the drive label attached by the drive manufacturer, that I have a 500 Gb (464 GiB) external drive. I'm running this on Firewire using a driver I got off of elrepo.org. When running gParted at boot with a Live CD, it looks like I have 750 Gb on this drive.
I can select /dev/sda, /dev/sdb and /dev/sdc in the upper right drop down menu.
/dev/sda 93.16 GiB
/dev/sda1 flag: boot, 101 MiB, ext3
/dev/sda2 flag: lvm, 93 GiB
unallocated : 2.4 MiB
/dev/sdb 189.92 GiB
/dev/sdb1 flag: boot, lvm 189.92 GiB)
unallocated : 6.64 MiB
/dev/sdc 465.76 GiB
/dev/sdc1 flag: EFI, 3.09 MiB, fat32
/dev/sdc2 flag: Martha 14, 465.44 GiB, hfs+
unallocated : 128.02 MiB
Add those up, (93.16 GiB+ 189.92 GiB + 465.76 GiB), and you get 748.84 GiB. I am really confused! Can you help me understand why my ~750 GiB external drive is really a 500 Gb (464 GiB) external drive?