A dump device is usually disk space that is reserved to store system crash dump information. By default, a system's dump device is configured to be a swap slice in a UFS root environment. If possible, you should configure an alternate disk partition as a dedicated dump device instead to provide increased reliability for crash dumps and faster reboot time after a system failure. You can configure a dedicated dump device by using the dumpadm command. For more information, see Chapter 17, Managing System Crash Information (Tasks), in System Administration Guide: Advanced Administration.
In a ZFS root environment, swap and dump are configured as separate ZFS volumes. The advantages to this model are as follows:
You don't have to partition a disk to include swap and dump areas
Swap and dump devices benefit from the underlying ZFS I/O pipeline architecture
You can set characteristics, such as compression, on swap and dump devices
You can easily reset swap and dump device sizes. For example:
# zfs set volsize=2G rpool/dump # zfs get volsize rpool/dump NAME PROPERTY VALUE SOURCE rpool/dump volsize 2G -
Keep in mind that reallocating a large dump device is a time-consuming process.
For more information about using ZFS swap and dump devices, see ZFS Support for Swap and Dump Devices in Solaris ZFS Administration Guide.
If you are using a volume manager to manage your disks in a UFS environment, such as Solaris Volume Manager, do not configure your dedicated dump device to be under its control. You can keep your swap areas under Solaris Volume Manager's control, which is a recommended practice. However, for accessibility and performance reasons, configure another disk as a dedicated dump device outside of Solaris Volume Manager's control.