Increase the swap partition size in linux

1. Accuracy
   Backup physical partition. Tools: fdisk,
   Partd. Note that if you want to operate on a partition on the hard disk separately, such as formatting the/dev/sda4 partition, the entire partition/dev/sda cannot be used.
   The root file system is on/dev/sda. You can only start linux to rescue mode on a CD and then format the file or perform other operations.
2. Create a swap filesystem, for example, [root @ jcwkyl vm] # mkswap
   /Dev/xen_space/swap
3. Activate the swap partition, for example, [root @ jcwkyl vm] # swapon
   /Dev/xen_space/swap
4. In/etc/fstab
   Add a record to the file to enable the swap partition to automatically mount:/dev/xen_space/swap when the system starts.
   Swap
   Swap
   Defaults 0 0
5. Verify that the swap partition has started working:
   [Root @ jcwkyl vm] # cat/proc/swaps
   Filename
   Type
   Size Used Priority
   /Dev/mapper/xen_space-swap
   Partition 5242872
   0-1
   Or:
   [Root @ jcwkyl vm] # free
   
   Total
   Used free
   Shared buffers cached
   Mem:
   1940480 486860
   1453620
   0 4452
   217220
   -/+ Buffers/cache: 265188 1675292
   Swap: 5242872 0 5242872