ServerBuddies Support Blog

Turn on DMA mode on a hard drive

DMA

Direct memory access (DMA) allows certain hardware subsystems within the computer to access system memory for reading and/or writing independently of the central processing unit. It uses a procedure called cycle stealing, where the central processor memory access cycles are delayed for very short times to intersperse DMA controller memory access cycles. DMA is used for transferring data between the local memory and the main memory.

You can turn On DMA mode on a hard drive

You can check whether DMA is enabled on a hard drive for the IDE harddrive.

If DMA is on, the output should contain the following line,

If it is off you can enable it as follows,

This will toggle the value of “using_dma” (It will turn off the value of “using_dma” if it was already on).

How to change the local timezone in Linux.

It is easy to change the timezone in Linux server. Replace your /etc/localtime file with the appropriate timezone data file from /usr/share/zoneinfo. For example, to set everything to Greenwich Mean Time (GMT), get a shell prompt and replace your /etc/localtime with /usr/share/zoneinfo/GMT by typing the following shell commands:

The first ‘date’ command will show you the current date/time before you change the timezone. The final ‘date’ command shows you current date/time in the timezone that you chose, which in this example is GMT.

There are many timezone data files in the zoneinfo directory and you can use any of them that you wish. To see them all, do:

So, symbolic linking /etc/localtime to any of those files, will change the time on server to that timezone.

Uninstalling VMware Workstation on a Linux Host.

Usually problem occurs when VMware is removed manually from Linux server. The easiest way to get it removed is by using the script or Redhat packet manager.

If you used the RPM installer to install VMware Workstation, remove the software from your system by running

If you cant find the package try

It will list the installed VMware package. Then perform

If you used the source to install VMware Workstation, remove the software from your system by running

Install VNC in VPS server with Gnome

VNC, or Virtual Networked Computing, is a way of controlling a remote server just as though you are sitting in front of it. Like RDP remote desktop connection in Windows we have VNC for Linux. You can connect using a VNC client to a remote server system running the VNC server, then an image of the remote desktop is transmitted to your local computer and you can see and control the desktop.

Usually Linux servers are not installed with graphical interface(only text mode). However, for VNC to gain access of the user friendly interface like windows, Gnome or KDE have to be installed.

Note : Please make sure you have at least 128MB of unused ram to allocate for VNC. Also, YUM and its required libraries are installed (python, sqlite, etc) on the server.

Installation :

1. Login as root to your server and run the following:

This will install Gnome and neccesary applications (VNC, FireFox, X11 libraries, etc) in the server.

2. Start up the vnc server with the ‘vncserver’ command and it will prompt you to enter a desired password. Just type what you want to use in and then confirm it. (if running as root, it will be in /.vnc or /root/.vnc or /home/root/.vnc)

3. Now, you’ll see VNC server is running by executing:

Now kill the VNC processes,

4. Edit xstartup file

Replace the last line(usually ‘twm & ‘ ) with ‘gnome-session & ‘ (without quotes of course). you can use ’startkde &’ for KDE

This tells VNC to startup GNOME instead of the default window manager, twm (or whatever the last line was).

5. Create users to VNCServer as follows,

Edit the lines below in the file /etc/sysconfig/vncservers and add a user (user should be a valid user created on your server and not just simply a name).

You can change the password of the VNCServer as :

If you want to change the password for the VNC user root, run the following
command from konsole,

6. Go ahead and execute the command ‘vncserver’ again, and VNC will startup, using the password specified earlier and create a default VNC instance on VNC port 1.

7. Start up your RealVNC client on your PC, and put in :1, and it should ask for your password that you put in earlier.

Disable journaling in ext3 file system

We know that EXT3 file system is nothing but EXT2 + a e. This allows faster FSCK process and avoids metadata corruption.

We can disable journaling (i.e convert EXT3 to EXT2) using tune2fs command.

Now the journaling is removed from /dev/xdy partition. The file system for this partition is know EXT2 rather than EXT3.

This is normally used when you want to re-size a partition.

If you want to convert it back to EXT3, use the following command:

Note: The partition should be un-mounted before converting the file-systems. For converting EXT2 to EXT3 you can also have the partition re-mounted as read-only too, but the former is safer.