JavaScript is required to for searching.
Skip Navigation Links
Exit Print View
System Administration Guide: Devices and File Systems     Oracle Solaris 10 8/11 Information Library
search filter icon
search icon

Document Information

About This Book

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: Setting Up Disks (Tasks)

13.  x86: Setting Up Disks (Tasks)

14.  Configuring Oracle Solaris iSCSI Targets and Initiators (Tasks)

15.  The format Utility (Reference)

16.  Managing File Systems (Overview)

17.  Creating and Mounting File Systems (Tasks)

18.  Using The CacheFS File System (Tasks)

19.  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 Unneeded Swap Space in UFS Root Environment

How to Remove a Swap Volume in a ZFS Root Environment

20.  Checking UFS File System Consistency (Tasks)

21.  UFS File System (Reference)

22.  Backing Up and Restoring UFS File Systems (Overview)

23.  Backing Up UFS Files and File Systems (Tasks)

24.  Using UFS Snapshots (Tasks)

25.  Restoring UFS Files and File Systems (Tasks)

26.  UFS Backup and Restore Commands (Reference)

27.  Copying Files and File Systems (Tasks)

28.  Managing Tape Drives (Tasks)


Monitoring Swap Resources

The /usr/sbin/swap command is used to manage swap areas. Two options, -l and -s, display information about swap resources.

Use the swap -l command to identify a system's swap areas. Activated swap devices or files are listed under the swapfile column. For example:

# swap -l
swapfile             dev  swaplo blocks   free
/dev/dsk/c0t0d0s1   136,1      16 1638608 1600528

On a system with a ZFS root file system, the swap -l command identifies similar output except that it identifies the ZFS volume path name. For example:

# swap -l
swapfile                  dev  swaplo blocks   free
/dev/zvol/dsk/rpool/swap 256,1      16 1058800 1058800

Use the swap -s command to monitor swap resources.

# swap -s
total: 57416k bytes allocated + 10480k reserved = 67896k used, 
833128k available

The used value plus the available value equals the total swap space on the system, which includes a portion of physical memory and swap devices (or files).

You can use the amount of available and used swap space (in the swap -s output) as a way to monitor swap space usage over time. If a system's performance is good, use swap -s to determine how much swap space is available. When the performance of a system slows down, check the amount of available swap space to determine if it has decreased. Then you can identify what changes to the system might have caused swap space usage to increase.

When using this command, keep in mind that the amount of physical memory available for swap usage changes dynamically as the kernel and user processes lock down and release physical memory.

Note - The swap -l command displays swap space in 512-byte blocks. The swap -s command displays swap space in 1024-byte blocks. If you add up the blocks from swap -l and convert them to KB, the result is less than used + available (in the swap -s output). The reason is that swap -l does not include physical memory in its calculation of swap space.

The output from the swap -s command is summarized in the following table.

Table 19-3 Output of the swap -s Command

bytes allocated
The total amount of swap space in 1024-byte blocks that is currently allocated as backing store (disk-backed swap space).
The total amount of swap space in 1024-byte blocks that is not currently allocated, but claimed by memory for possible future use.
The total amount of swap space in 1024-byte blocks that is either allocated or reserved.
The total amount of swap space in 1024-byte blocks that is currently available for future reservation and allocation.