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Oracle Solaris Administration: Devices and File Systems     Oracle Solaris 11 Information Library
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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 Storage Devices With COMSTAR

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

16.  The format Utility (Reference)

17.  Managing File Systems (Overview)

18.  Creating and Mounting File Systems (Tasks)

19.  Configuring Additional Swap Space (Tasks)

About Swap Space

Swap Space and Virtual Memory

Swap Space and the TMPFS File System

Swap Space and Dump Device Configuration

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 ZFS-Based Systems

Monitoring Swap Resources

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

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

20.  Copying Files and File Systems (Tasks)

21.  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.

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.

Table 19-1 Swap and Dump Volume Sizes for ZFS File Systems

System Type
Swap Volume Size
Dump Volume Size
System with about 4 GB of physical memory
1 GB
2 GB
Mid-range server with about 8 GB of physical memory
2 GB
4 GB
High-end server with about 16 to 128 GB of physical memory
4 GB
8-64 GB
High-end server with more than 128 GB of physical memory
1/4 of physical memory size
1/2 of physical memory size

Note - A busy system with many active ZFS file systems might use 1/2 to 3/4 the size of physical memory for the size of the dump device.

On a system with a ZFS root file system, if you attempt to designate a dump device that is too small to hold a system crash system with the dumpadm -d command, you will see a message similar to the following:

dumpadm: dump device /dev/zvol/dsk/rpool/dump is too small to hold a
system dump dump size 43467329536 bytes, device size 42949672960 bytes

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.

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.