Swap is a space on a disk that is used when the amount of physical RAM memory is full. When a Linux system runs out of RAM, inactive pages are moved from the RAM to the swap space. Swap space can take the form of either a dedicated swap partition or a swap file.
NAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
/dev/dm-2 partition 4G 0B -2
[root@Server ~]# swapoff /dev/dm-2
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
[root@Server ~]#
[root@Server ~]# lvremove /dev/appvg/swap2
Do you really want to remove active logical volume appvg/swap2? [y/n]: y
Logical volume "swap2" successfully removed
[root@Server ~]# vgs
VG #PV #LV #SN Attr VSize VFree
appvg 2 9 0 wz--n- 124.99g 35.99g
rootvg 1 11 0 wz--n- 45.59g 3.38g
[root@Server ~]# lsblk -l | grep -i sdd
sdd 8:48 0 15G 0 disk
[root@Server ~]#
[root@Server ~]# fdisk /dev/sdd
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x8c1fe0d2.
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-31457279, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-31457279, default 31457279):
Partition 1 of type Linux and size 15 GiB is set
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
/dev/sdd1 2048 30722047 15360000 83 Linux
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx
5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data
6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility
8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt
9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access
a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT
1e Hidden W95 FAT1 80 Old Minix
Hex code (type L to list all codes): 82
Changed type of partition 'Linux' to 'Linux swap / Solaris'
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
/dev/sdd1 2048 30722047 15360000 82 Linux swap / Solaris
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@Server ~]# partprobe
[root@Server ~]#
[root@Server ~]# mkswap /dev/sdd1
Setting up swapspace version 1, size = 15359996 KiB
no label, UUID=caf2bb4e-23ea-4e8a-8843-0020eac8e77f
[root@Server ~]# echo "UUID=caf2bb4e-23ea-4e8a-8843-0020eac8e77f swap swap defaults 0 0" >> /etc/fstab
[root@Server ~]# swapon -a
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
/dev/sdd1 partition 14.7G 0B -2
[root@Server ~]# swapoff /dev/sda2
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sdd1 partition 14.7G 0B -1
[root@Server ~]# vgextend rootvg /dev/sda2
WARNING: swap signature detected on /dev/sda2 at offset 4086. Wipe it? [y/n]: y
Wiping swap signature on /dev/sda2.
Physical volume "/dev/sda2" successfully created.
Volume group "rootvg" successfully extended
[root@Server ~]# vgs
VG #PV #LV #SN Attr VSize VFree
appvg 2 9 0 wz--n- 124.99g 35.99g
rootvg 2 11 0 wz--n- 49.47g 7.25g
Recommendation:
If RAM is 1-2 GB, it is recommended to use twice the SWAP space as amount of RAM.
If RAM is 2-16 GB, SWAP is recommended to be equal to amount of RAM.
If RAM is above 16 GB, SWAP of minimum 16 GB should be fine.
Steps:
[root@Server ~]# swaponNAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
/dev/dm-2 partition 4G 0B -2
[root@Server ~]# swapoff /dev/dm-2
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
[root@Server ~]#
[root@Server ~]# lvremove /dev/appvg/swap2
Do you really want to remove active logical volume appvg/swap2? [y/n]: y
Logical volume "swap2" successfully removed
[root@Server ~]# vgs
VG #PV #LV #SN Attr VSize VFree
appvg 2 9 0 wz--n- 124.99g 35.99g
rootvg 1 11 0 wz--n- 45.59g 3.38g
[root@Server ~]# lsblk -l | grep -i sdd
sdd 8:48 0 15G 0 disk
[root@Server ~]#
[root@Server ~]# fdisk /dev/sdd
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x8c1fe0d2.
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
Command (m for help): n
Partition type:
p primary (0 primary, 0 extended, 4 free)
e extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-31457279, default 2048):
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-31457279, default 31457279):
Partition 1 of type Linux and size 15 GiB is set
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
/dev/sdd1 2048 30722047 15360000 83 Linux
Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): L
0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris
1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-
2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-
3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-
4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx
5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data
6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .
7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility
8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt
9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS access
a OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/O
b W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStor
c W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fs
e W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPT
f W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/
10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b
11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor
12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor
14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary
16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS
17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE
18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto
1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep
1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT
1e Hidden W95 FAT1 80 Old Minix
Hex code (type L to list all codes): 82
Changed type of partition 'Linux' to 'Linux swap / Solaris'
Command (m for help): p
Disk /dev/sdd: 16.1 GB, 16106127360 bytes, 31457280 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 label type: dos
Disk identifier: 0x8c1fe0d2
Device Boot Start End Blocks Id System
/dev/sdd1 2048 30722047 15360000 82 Linux swap / Solaris
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@Server ~]# partprobe
[root@Server ~]#
[root@Server ~]# mkswap /dev/sdd1
Setting up swapspace version 1, size = 15359996 KiB
no label, UUID=caf2bb4e-23ea-4e8a-8843-0020eac8e77f
[root@Server ~]# echo "UUID=caf2bb4e-23ea-4e8a-8843-0020eac8e77f swap swap defaults 0 0" >> /etc/fstab
[root@Server ~]# swapon -a
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sda2 partition 3.9G 0B -1
/dev/sdd1 partition 14.7G 0B -2
[root@Server ~]# swapoff /dev/sda2
[root@Server ~]# swapon
NAME TYPE SIZE USED PRIO
/dev/sdd1 partition 14.7G 0B -1
[root@Server ~]# vgextend rootvg /dev/sda2
WARNING: swap signature detected on /dev/sda2 at offset 4086. Wipe it? [y/n]: y
Wiping swap signature on /dev/sda2.
Physical volume "/dev/sda2" successfully created.
Volume group "rootvg" successfully extended
[root@Server ~]# vgs
VG #PV #LV #SN Attr VSize VFree
appvg 2 9 0 wz--n- 124.99g 35.99g
rootvg 2 11 0 wz--n- 49.47g 7.25g
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