Add second swap partition on CentOS 6
Posted On October 13, 2016
Swap space is extremely important for Linux system. It acts like temporary storage for process memory image. There are many reasons to have multiple swap areas. We will take a look at the process of creating additional swap partition on already existing system.
In our example system was partiiotned with 3 primary partitions. / /boot and swap
[root@rh ~]#fdisk -l Disk /dev/sda: 8589 MB, 8589934592 bytes 255 heads, 63 sectors/track, 1044 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: 0x00018a08 Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 192 1024000 83 Linux Partition 2 does not end on cylinder boundary. /dev/sda3 192 217 204800 82 Linux swap / Solaris Partition 3 does not end on cylinder boundary.
[root@rh ~]# mount /dev/sda2 on / type ext4 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) tmpfs on /dev/shm type tmpfs (rw,rootcontext="system_u:object_r:tmpfs_t:s0") /dev/sda1 on /boot type ext4 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)
[root@rh ~]# free total used free shared buffers cached Mem: 1020592 129264 891328 0 6768 39124 -/+ buffers/cache: 83372 937220 Swap: 204792 0 204792
Create extended partition
Since we already have 3 primary partitions created. We will start by creting extended partition which within itself will be holding logical volume with our swap partition.
First we run parted /dev/sda print free to see all free space available
[root@rh ~]# parted /dev/sda print free Model: ATA QEMU HARDDISK (scsi) Disk /dev/sda: 8590MB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 32.3kB 1049kB 1016kB Free Space 1 1049kB 525MB 524MB primary ext4 boot 2 525MB 1574MB 1049MB primary ext4 3 1574MB 1784MB 210MB primary linux-swap(v1) 1784MB 8590MB 6806MB Free Space
1. Create extended partition
fdisk /dev/sda n for new e for extended select 4 for partition number Use default value for number of cilinders +6G to add 6gb extended partition p to make sure everyhtong is correct w apply the changes
[root@rh ~]# fdisk /dev/sda
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
e
Selected partition 4
First cylinder (217-1044, default 217):
Using default value 217
Last cylinder, +cylinders or +size{K,M,G} (217-1044, default 1044): +6G
Command (m for help): p
Disk /dev/sda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 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: 0x00018a08
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 192 1024000 83 Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3 192 217 204800 82 Linux swap / Solaris
Partition 3 does not end on cylinder boundary.
/dev/sda4 217 1000 6290676 5 Extended
Command (m for help): w
[root@rh ~]# fdisk -l Disk /dev/sda: 8589 MB, 8589934592 bytes 255 heads, 63 sectors/track, 1044 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: 0x00018a08 Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 192 1024000 83 Linux Partition 2 does not end on cylinder boundary. /dev/sda3 192 217 204800 82 Linux swap / Solaris Partition 3 does not end on cylinder boundary. /dev/sda4 217 1000 6290676 5 Extended [label type="label" style="default" title="Create swap partition"]
[root@rh ~]# fdisk /dev/sda
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): p
Disk /dev/sda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 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: 0x00018a08
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 192 1024000 83 Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3 192 217 204800 82 Linux swap / Solaris
Partition 3 does not end on cylinder boundary.
/dev/sda4 217 1000 6290676 5 Extended
Command (m for help): n
First cylinder (217-1000, default 217):
Using default value 217
Last cylinder, +cylinders or +size{K,M,G} (217-1000, default 1000): +200M
Command (m for help): t
Partition number (1-5): 5
Hex code (type L to list codes): 82
Changed system type of partition 5 to 82 (Linux swap / Solaris)
Command (m for help): p
Disk /dev/sda: 8589 MB, 8589934592 bytes
255 heads, 63 sectors/track, 1044 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: 0x00018a08
Device Boot Start End Blocks Id System
/dev/sda1 * 1 64 512000 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 64 192 1024000 83 Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3 192 217 204800 82 Linux swap / Solaris
Partition 3 does not end on cylinder boundary.
/dev/sda4 217 1000 6290676 5 Extended
/dev/sda5 217 242 202009+ 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.
[root@rh ~]# [root@rh ~]# mkswap /dev/sda5 Setting up swapspace version 1, size = 105612 KiB no label, UUID=94039809-db22-4411-91bd-95d0dfd6559f [root@rh ~]# free total used free shared buffers cached Mem: 1020592 179612 840980 0 8740 85420 -/+ buffers/cache: 85452 935140 Swap: 204792 0 204792 [root@rh ~]# swapon /dev/sda5 [root@rh ~]# free total used free shared buffers cached Mem: 1020592 179612 840980 0 8744 85420 -/+ buffers/cache: 85448 935144 Swap: 310400 0 310400
Make changes permanent
To make chnages permanent the following line should be entered in /etc/fstab
/dev/sda5 swap swap defaults 0 0