Resolves low memory---as slave virtual machine under Ubuntu

1) on the virtual machine installed Ubuntu Desktop version as Datanode, because the physical machine memory limit only divided 1G of memory to the virtual machine, using bin/start-all.sh started Hadoop, slave resource usage as shown:

A total of 986M of memory was used for 574M, which has not yet started to run the Mr Program.

2) Workaround: Set to enable Ubuntu to boot directly into the command line mode, rather than desktop mode. Use the following command to set up

sudo gedit/etc/default/grub

Find this line

grub_cmdline_linux_default="quiet Splash"

Change into

grub_cmdline_linux_default="quiet Splash text"

Re-enter the command:

sudo update-grub

It automatically enters the command line (tty1) after booting.

In addition, sometimes you may need to enter the desktop mode, command-line mode needs to return to the graphics mode, input command: STARTX

If you want to switch back again, just restart it, because this can happen with CTRL+ALT+F1:

3) Finally, using command-line mode, when running Hadoop, memory usage is as follows:

When command-line mode is turned on, memory usage is reduced to 235M, saving 300+m.

Resolves low memory---as slave virtual machine under Ubuntu