I created a partition called /dev/sda3 as a swap partition, and changed the ID to 82 (Linux Swap) via fdisk. If this partition was recognized as a swap partition (seen in the output of fdisk -l and blkid), then why couldn't I proceed straight to swapon /dev/sda3? Why did I have to execute mkswap /dev/sda3? Another question, is partition information exclusive from data? So if I changed a filesystem type via fdisk would data be affected?
Disk /dev/sda: 21.5 GB, 21474836480 bytes 255 heads, 63 sectors/track, 2610 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0008d6ed Device Boot Start End Blocks Id System /dev/sda1 * 1 32 256000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 32 1566 12317696 83 Linux /dev/sda3 1566 2610 8390105 82 Linux swap / Solaris
/dev/sda3: LABEL="SWAP" UUID="63f1807e-7cc6-4339-92b2-b1958fcf285e" TYPE="swap"