My apology if my question sounded silly, but I am very new to ubuntu. I have just formatted my pc to ubuntu. However, I found out that now I have 3 partitions in my harddisk. One is the ext4 /dev/sda1 which is the system file partition. However, I noticed that I have another partition called extended /dev/sda2 3.08G, and the linux-swap /dev/sda5 is under the extended partition as shown in gparted. May I know is the ubuntu installed correctly? I can only access to my main system partition, and have lost 6G. My harddisk is 80G and ram 1.5G. Thanks.
Seems to be okay. The swap partition is used as virtual memory to extend your RAM. If you want u can remove it, but if you frequently max out your RAM you might wanna leave it. If you do remove it, its not a bad idea to delete its "mount line" in /etc/fstab (needs root privileges).
swap partition is in
extended, then you can't add them (2*3 = 6), but it is together 3G. And that's a reasonable amount, if you have 1.5 G real RAM. Or did I misunderstand? How big is the system partition?
You have to use the same tools, to take the measurements, since 80GB isn't 80GiB - often the numbers are intermixed, and then you get wrong results.