[Computer System] Delay of SSH

Empirical Setting:

The delay of response of command built upon ssh protocol (git, ssh...etc) come from the setting of

GSSAPIAuthentication


Turn it off in the ~/.ssh/config
GSSAPIAuthentication no

[Computer System] Linux /bin, /sbin/, /usr/bin, /usr/sbin

/bin: 
  This directory contains executable programs which are needed in single user mode and for all users.

/sbin: 

  Like /bin, this directory holds commands needed to boot the system such as init, ip, mount, but those commands are not frequently executed by normal users.

/usr/bin:

  This is the primary directory for executable programs and for all users.

/usr/sbin:

  This directory contains program binaries for system administration which are not essential for the boot process, for mounting /usr or for system repair.

/usr/local:
  Neither of the above. Please use /usr/local/bin or /usr/local/sbin for system-wide available scripts. The local path means it's not managed by the system packages

Reference: 

1. Filesystem Hierarchy Standard
2. Single User Mode
3. Ubuntu Explaination

Note: Ubuntu 13 Installation in SSD

Enable the AHCI mode in BIOS;

Construct gpt partition table (In the older machine, gpt need the aid of BIOS to help construct the boot table. Therefore, we use the default partition (MSDOS) instead), which, however, I don't really understand the reason.

Check I/O Scheduler (use Deadline by default for SSD in Ubuntu 13)

Alignment is handled by the Gparted, and. on the other hand, there is not so much performance difference.

1. While the installation process, we need to mount the partition just formatted mount as root.
2. Installing...
3. Enable TRIM (Good Explanation of TRIM, Related)