Introduction
The swap space is used by the OS to handle overflow for parts of the RAM that are currently not being used.
The recommended size of the swap space is depending on how much RAM you have.
- < 2GB RAM, use 2 * RAM
- >= 2GB RAM, use RAM + 2GB
How to Create a New Swap Partition
$ fdisk -cul /dev/sda
Disk /dev/sda: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x7f3d8c0f
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 205826047 102400000 8e Linux LVM
$ fdisk -cu /dev/sda
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 3
First sector (205826048-488397167, default 205826048):
Using default value 205826048
Last sector, +sectors or +size{K,M,G} (205826048-488397167, default 488397167): +1G
Command (m for help): t
Partition number (1-4): 3
Hex code (type L to list codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 39 Plan 9 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 3c PartitionMagic 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 40 Venix 80286 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 41 PPC PReP Boot 85 Linux extended c7 Syrinx
5 Extended 42 SFS 86 NTFS volume set da Non-FS data
6 FAT16 4d QNX4.x 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS 4e QNX4.x 2nd part 88 Linux plaintext de Dell Utility
8 AIX 4f QNX4.x 3rd part 8e Linux LVM df BootIt
9 AIX bootable 50 OnTrack DM 93 Amoeba e1 DOS access
a OS/2 Boot Manag 51 OnTrack DM6 Aux 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 52 CP/M 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 53 OnTrack DM6 Aux a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 54 OnTrackDM6 a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 55 EZ-Drive a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 56 Golden Bow a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 5c Priam Edisk a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 61 SpeedStor a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 63 GNU HURD or Sys ab Darwin boot f2 DOS secondary
16 Hidden FAT16 64 Novell Netware af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 65 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 70 DiskSecure Mult b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 75 PC/IX bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 80 Old Minix be Solaris boot ff BBT
1e Hidden W95 FAT1
Hex code (type L to list codes): 82
Changed system type of partition 3 to 82 (Linux swap / Solaris)
Command (m for help): p
Disk /dev/sda: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x7f3d8c0f
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 205826047 102400000 8e Linux LVM
/dev/sda3 205826048 207923199 1048576 82 Linux swap / Solaris
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)
Syncing disks.
$ reboot
After reboot we need to format the new swap partition.
$ mkswap /dev/sda3
Setting up swapspace version 1, size = 1048572 KiB
no label, UUID=b28d9a2c-51a4-45e8-a0d3-d4b457afa359
Next step is to activating it.
$ swapon -a /dev/sda3
To verify/list current swap spaces.
$ swapon -s
Filename Type Size Used Priority
/dev/dm-0 partition 4095992 0 -1
/dev/sda3 partition 1048568 0 -2
To make this new swap space persistent, we need to add this new swap space to /etc/fstab.
$ blkid /dev/sda3
/dev/sda3: UUID="b28d9a2c-51a4-45e8-a0d3-d4b457afa359" TYPE="swap"
$ vi /etc/fstab
UUID=b28d9a2c-51a4-45e8-a0d3-d4b457afa359 swap swap defaults 0 02
Reboot and verify that new swap space is active.
How to Remove a Swap Partition
First deactive it.
$ swapoff /dev/sda3
Verify it is no longer active.
$ swapon -s
Filename Type Size Used Priority
/dev/dm-0 partition 4095992 0 -1
IF YOU HAVE ADDED IT TO /etc/fstab, DO NOT FORGET TO REMOVE IT FROM THERE AS WELL!
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