ubuntu

 

 


Version number & Name

 

 年.月

20.04 - Focal Fossa

18.04 - Bionic Beaver

16.04 - Xenial Xerus

14.04 - Trusty Tahr

12.04 - Precise Pangolin

 


LTS

 

  • supported for five years
  • Business and enterprise users can get "extended maintenance release" (ESM) support for 10 years.

 


20.04 LTS

 

  • Linux Kernel 5.4
  • Kernel and initramfs compression algorithm has changed to lz4
  • Hypervisor: QEMU (v4.2), libvirt (v6.0)
  • Containers: lxd, lxc
  • Developer: Python 3.8.2, php 7.4, MySQL (v8.0) and NGINX (v1.17)
  • Snap-based Ubuntu Software app
  • SSH two-factor authentication
  • AppArmor 3

 


18.04 LTS

 

  • Linux Kernel 4.15
  • QEMU 2.11.1 libvirt 4.0
  • ships with LXD 3.0
  • New default networking queue management algorithms
  • BTRFS swap file support
  • swap file will be used by default instead of a swap partition
  • New block I/O latency controller
  • shiftfs filesystem providing LXD performance improvements
  • The default DNS resolver is systemd-resolved.
  • Python 3.6, Nginx 1.14.0, PHP 7.2, Apache 2.4.29

 


16.04 LTS

 

 


14.04 LTS

 

* 64-bit only
* Linux kernel 3.13

* Open vSwitch 2.0.1
* ship only Python 3 ( Python 2 = python package)

* Ceph 0.79 ( distributed object store and file system designed to provide excellent performance, reliability and scalability )

* Qemu 2
* Libvirt 1.2.2
* LXC 1.0

* MAAS 1.5 (Metal as a Service)
 - MAAS turns your bare metal into an elastic cloud-like resource.

* juju
 - Juju enables you to use Charms to deploy your application architectures to EC2, OpenStack, Azure
   Juju Charms define applications as services. There are 100s of Charms already created by application experts.
    = hadoop
    = mysql
    =ceph

* Apache 2.4
* PHP 5.5

* AppArmor 2.8.95

DB:

  • Percona XtraDB Cluster 5.5
  • MariaDB 5.5
  • MariaDB 5.5

* strongSwan

 


Backports

 

/etc/apt/sources.list

12.04

deb mirror://mirrors.ubuntu.com/mirrors.txt precise-backports main restricted universe

14.04

deb http://archive.ubuntu.com/ubuntu trusty-backports main restricted universe multiverse

# Configuring Backports for Manual Install

/etc/apt/preferences

Package: *
Pin: release a=precise-backports
Pin-Priority: 100

Install backport package

apt-get install btrfs-tools/precise-backports

E: Release 'precise-backports' for 'btrfs-tools' was not found

 


Kernel Difference

 

常見的 Kernel Package 有

  • linux-image-server package is a meta package that will install the latest Server kernel version
  • linux-image-generic package is a meta package for the latest Desktop kernel version
  • linux-image-3.2.0-54-virtual
  • linux-image-3.2.0-41-lowlatency

12.04 已沒有分 server 與 generic 了

原因:

an effort to reduce the maintenance burden over the life of the LTS

server 與 generic 的不同

  • default I/O scheduler
  • preemption model.

The virtual kernel only includes the necessary drivers to run inside popular virtualization technologies such as KVM, Xen, and VMWare.

lowlatency:

linux-lowlatency is based on the Ubuntu linux-generic kernel.
It has a few differing configurations to allow for more aggressive preempting.

https://wiki.ubuntu.com/RealTime

Ubuntu Studio 是用它的

linux-lowlatency is being able to achieve software processing with latencies well below the human perception threshold of 5 to 10 ms.

The scheduler allows applications to request immediate CPU time, which can drastically reduce audio latency.

 


Service

 

upstart-socket-bridge

DESCRIPTION

       The  upstart-socket-bridge  queries  the Upstart init(8) daemon for all
       job configurations which start on or stop on the socket event. It  then
       waits  for  an incoming connection on each specified socket(7) and when
       detected emits the socket event (socket-event (7)), setting a number of
       environment variables for the job to query.

gam_server

/usr/lib/gamin/gam_server

Gamin is a monitoring system for files and directories that independently implements a subset of FAM, the File Alteration Monitor. Running as a service, it allows for the detection of modifications to a file or directory. gam_server functions as a daemon for Gamin.

ondemand

 "ondemand" CPU scaling daemon

update-rc.d -f ondemand remove

/etc/init.d/ondemand

 


Other

 

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