System Administration Guide, Volume 1

How Swap Space Is Allocated

Initially, swap space is allocated as part of the Solaris installation process. If you use the installation program's automatic layout of disk slices and do not manually change the size of the swap slice, the Solaris installation program allocates default swap slices as shown in the table below.

Table 38-1 Default Swap Space Allocations

If Your System Has n Mbytes of Physical Memory ...

Then the Default Swap Space Allocated Is ... 


32 Mbytes 


64 Mbytes 


128 Mbytes 

greater than 512 

256 Mbytes 

Additional swap space can also be added to the system by creating a swap file. See "Adding More Swap Space" for information about creating a swap file.

The /etc/vfstab File

After the system is installed, swap slices and files are listed in the /etc/vfstab file and are activated by the /sbin/swapadd script when the system is booted.

An entry for a swap device in the /etc/vfstab file contains:

Because the file system containing a swap file must be mounted before the swap file is activated, make sure that the entry that mounts the file system comes before the entry that activates the swap file in the /etc/vfstab file.