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System Administration Guide: Devices and File Systems     Oracle Solaris 11 Express 11/10
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Document Information


1.  Managing Removable Media (Overview)

2.  Managing Removable Media (Tasks)

3.  Accessing Removable Media (Tasks)

4.  Writing CDs and DVDs (Tasks)

5.  Managing Devices (Overview/Tasks)

6.  Dynamically Configuring Devices (Tasks)

7.  Using USB Devices (Overview)

8.  Using USB Devices (Tasks)

9.  Using InfiniBand Devices (Overview/Tasks)

10.  Managing Disks (Overview)

11.  Administering Disks (Tasks)

12.  SPARC: Adding a Disk (Tasks)

13.  x86: Adding a Disk (Tasks)

14.  Configuring iSCSI Storage Devices With COMSTAR

15.  Configuring and Managing the Solaris Internet Storage Name Service (iSNS)

16.  Managing Disk Use (Tasks)

17.  The format Utility (Reference)

18.  Managing File Systems (Overview)

19.  Creating ZFS, UFS, TMPFS, and LOFS File Systems (Tasks)

20.  Mounting and Unmounting File Systems (Tasks)

21.  Configuring Additional Swap Space (Tasks)

About Swap Space

Swap Space and Virtual Memory

Swap Space and the TMPFS File System

Swap Space as a Dump Device

Swap Space and Dynamic Reconfiguration

Configuring Swap Space in a SAN Environment

How Do I Know If I Need More Swap Space?

Swap-Related Error Messages

TMPFS-Related Error Messages

How Swap Space Is Allocated

Swap Areas and the /etc/vfstab File

Planning for Swap Space

Allocating Swap Space for UFS-Based Systems

Allocating Swap Space for ZFS-Based Systems

Monitoring Swap Resources

Adding More Swap Space

Creating a Swap File in a UFS Root Environment

mkfile Command

How to Create a Swap File and Make It Available in UFS Root Environment

Adding or Changing Swap Space in an Oracle Solaris ZFS Root Environment

How to Add Swap Space in an Oracle Solaris ZFS Root Environment

Removing a Swap File From Use

How to Remove a Swap Volume in a ZFS Root Environment

22.  Copying Files and File Systems (Tasks)

23.  Managing Tape Drives (Tasks)


Planning for Swap Space

The most important factors in determining swap space size are the requirements of the system's software applications. For example, large applications such as computer-aided design simulators, database management products, transaction monitors, and geologic analysis systems can consume as much as 200–1000 MB of swap space.

Consult your application vendors for swap space requirements for their applications.

If you are unable to determine swap space requirements from your application vendors, use the following general guidelines based on your system type to allocate swap space.

System Type
Swap Space Size
Dedicated Dump Device Size
System with about 4 GB of physical memory
1 GB
1 GB
Mid-range server with about 8 GB of physical memory
2 GB
2 GB
High-end server with about 16 to 128 GB of physical memory
4 GB
4 GB
High-end server with more than 128 GB of physical memory
1/4 of physical memory size
1/4 of physical memory size

Note - Crash dump content is compressed so the dump device does not have to be the same size as physical memory. By default, the dump content value is set to kernel pages. However, if the dump content value is set to dump all memory pages, then consider increasing the dump size to half the size of physical memory or more.

Allocating Swap Space for UFS-Based Systems

In addition to preceding general guidelines, consider allocating swap space or disk space for a UFS-based system for the following:

Allocating Swap Space for ZFS-Based Systems

During an initial installation of a ZFS root file system, a swap area is automatically created on a ZFS volume in the ZFS root pool, generally in the 512 MB to 2 GB range.

In a ZFS root pool, swap devices are not pre-allocated to fixed-size slices, so it is fairly easy to modify the swap size later.

After you assess the swap requirements of your applications, you can use the default swap size or adjust the swap volume size during an initial installation or after the installation, if necessary.

During an initial installation, the default dump volume size is calculated by the kernel based on dumpadm information and the size of physical memory.

In a ZFS environment, file systems consume space from the pool so the /var/crash directory consumes what it needs depending on how many crash dumps are saved.