Sendmail

What Sendmail does:

• Listen on network ports for mail.
• Sort mail and deliver it locally or externally to other servers.
• Append mail to files or pipe it through other programs.
• Queue mail (if immediate delivery fails).
• Convert email addresses to/from user names, or handle mailing lists.
• Reads rules for special mail handling, so it can try to catch spam, or check for correctness.

Basics of Shell Programming

1. To get a Linux shell, you need to start a terminal.
2. To see what shell you have, run: echo $SHELL.
3. In Linux, the dollar sign ($) stands for a shell variable.
4. The ‘echo‘ command just returns whatever you type in.
5. The pipeline instruction (|) comes to rescue, when chaining several commands.
6. Linux commands have their own syntax, Linux won’t forgive you whatsoever is the mistakes. If you get a command wrong, you won’t flunk or damage anything, but it won’t work.
7. #!/bin/sh – It is called shebang. It is written at the top of a shell script and it passes the instruction to the program /bin/sh.

Xen Server : Features Comparison

	Xen 4.0	Xen 4.1	Xen 4.2	Xen 4.3
Initial Release	7-Apr-10	25-Mar-11	17-Sep-12	2-Jul-13
Feature List			FL 4.2	FL 4.3
Release Notes	RN 4.0	RN 4.1	RN 4.2	RN 4.3
Supported Mainline Architectures
IA-A32	✓	✓	✓	✓
X86-64	✓	✓	✓	✓
Itanium	✓	✓deprecated in this release	✓deprecated
ARM v7 + Virtualization Extensions				✓tech preview [ 6 ]
ARM v8				✓tech preview [ 6 ]
Guest Types
For X86 Architectures
Paravirtualised	✓	✓	✓	✓
Traditional Xen PV guest
HVM Guest [ 1 ]	✓	✓	✓	✓
Fully virtualised guest using hardware virtualisation extensions
PV-on-HVM Guest [ 1 ]	✓	✓	✓	✓
Fully virtualised guest using PV extensions/drivers for improved performance
For ARM Architectures
ARM Guest				✓tech preview [ 6 ]
Optimal combination of full virtualization and PV extensions
Host Limits
For X86 Architectures
Physical CPUs	128 [ 0 ]	>255	4095	4095
Physical RAM	1TB	5TB	5TB	16TB
For ARM Architectures
Physical CPUs				8
Physical RAM				16GB
Guest Limits
X86 PV Guest Limits
Virtual CPUs	128	>255	512	512
Virtual RAM	512GB	512GB	512GB	512GB
X86 HVM Guest Limits
Virtual CPUs	128	128	256	256
Virtual RAM	1TB	1TB	1TB	1TB
ARM Guest Limits
Virtual CPUs				8
Virtual RAM				16GB
Toolstack
Built-in
xend / xm	✓	✓	✓deprecated in this release	✓deprecated
XL	✓initial implementation	✓preview release	✓	✓
Qemu based disk backend (qdisk) for XL		✓ [ 5 ]	✓ [ 5 ]	✓ [ 5 ]
XL Open vSwitch integration				✓tech preview [ 7 ]
3rd Party
libvirt driver for XL		✓	✓	✓
Features
Advanced Memory Management
Memory Ballooning	✓	✓	✓	✓
Memory Sharing	✓tech preview	✓tech preview	✓tech preview [ 3 ]	✓tech preview [ 3 ]
allow sharing of identical pages between HVM guests
Memory Paging	✓tech preview	✓tech preview	✓tech preview [ 3 ]	✓tech preview [ 3 ]
allow pages belonging to HVM guests to be paged to disk
TMEM - Transcendent Memory	✓experimental [ 2 ]	✓experimental [ 2 ]	✓experimental [ 2 ]	✓experimental [ 2 ]
Resource Management
Cpupool		✓	✓	✓
advanced partitioning
Credit 2 Scheduler		✓prototype	✓prototype	✓experimental
designed for latency-sensitive workloads and very large systems.
NUMA scheduler affinity				✓
Scalability
1GB/2MB super page support		✓	✓	✓
Deliver events to PVHVM guests using Xen event channels		✓	✓	✓
Interoperability / Hardware Support
Nested Virtualisation			✓experimental	✓experimental
Running a hypervisor inside an HVM guest
HVM PXE Stack	gPXE	iPXE	iPXE	iPXE
Physical CPU Hotplug	✓	✓	✓	✓
Physical Memory Hotplug	✓	✓	✓	✓
Support for PV kernels in bzImage format	✓	✓	✓	✓
PCI Passthrough	✓	✓	✓	✓
X86 Advanced Vector eXtension (AVX)		✓ [ 4 ]	✓	✓
High Availability and Fault Tolerance
Live Migration, Save & Restore	✓	✓	✓	✓
Remus Fault Tolerance	✓	✓	✓	✓
vMCE	?	?	✓	✓
Forward Machine Check Exceptions to Appropriate guests
Network and Storage
Blktap2	✓	✓	✓	✓
Online resize of virtual disks	✓	✓	✓	✓
Security (also see this presentation or this document)
Driver Domains	✓	✓	✓	✓
Device Model Stub Domains	✓	✓	✓	✓
Memaccess API		✓	✓	✓
enabling integration of 3rd party security solutions into Xen virtualized environments
XSM & FLASK	✓	✓	✓	✓
mandatory access control policy providing fine-grained controls over Xen domains, similar to SELinux
XSM & FLASK support for IS_PRIV				✓
vTPM Support	✓	✓	✓	✓
				updates and new functionality
Tooling
gdbsx	✓	✓	✓	✓
debugger to debug ELF guests
vPMU	✓ [ 4 ]	✓ [ 4 ]	✓ [ 4 ]	✓ [ 4 ]
Virtual Performance Management Unit for HVM guests
Serial console	✓	✓	✓	✓Add EHCI debug support
xentrace	✓	✓	✓	✓
performance analysis
Device Models and Virtual Firmware for HVM guests
For X86 Architectures
Traditional Device Model	✓	✓	✓	✓
Device emulator based on Xen fork of Qemu
Qemu Upstream Device Model			✓tech preview	✓default, unless stubdomains are used
Device emulator based on upstream Qemu
ROMBIOS	✓	✓	✓	✓
BIOS used with traditional device model only
SeaBIOS			✓	✓
BIOS used with upstream qemu device model and XL only
OVMF/Tianocore			✓experimental [ 4 ]	✓experimental [ 4 ]
UEFI Firmware used with upstream qemu device model and XL only
PV Bootloader support
For X86 Architectures
PyGrub support for GRUB 2	✓	✓	✓	✓
PyGrub support for /boot on ext4	✓	✓	✓	✓
pvnetboot support			✓	✓
Bootloader supporting network boot of PV guests

Fedora 19 New Features : NFStest

 NFStest provides a set of tools for testing either the NFS client or the NFS server, included tests focused mainly on testing the client.

 Test utilities package

Provides a set of tools for testing either the NFS client or the NFS server, most of the functionality is focused mainly on testing the client. These tools include the following:

• Process command line arguments
• Provide functionality for PASS/FAIL
• Provide test grouping functionality
• Provide multiple client support
• Logging mechanism
• Debug info control
• Mount/Unmount control
• Create files/directories
• Provide mechanism to start a packet trace
• Provide mechanism to simulate a network partition
• Support for pNFS testing

Installation

Install the rpm as root

# rpm -i NFStest-1.0.1-1.noarch.rpm

All manual pages are available

$ man nfstest

Run tests:

$ nfstest_pnfs --help

Untar the tarball

$ cd ~

$ tar -zxvf NFStest-1.0.1.tar.gz

The tests can run without installation, just set the python path

environment variable:

$ export PYTHONPATH=~/NFStest-1.0.1

$ cd NFStest-1.0.1/test

$ ./nfstest_pnfs --help

Or install to standard python site-packages and executable directories:

$ cd ~/NFStest-1.0.1

$ sudo python setup.py install

All manual pages are available

$ man nfstest

Run tests:

$ nfstest_pnfs --help

Clone the git repository

$ cd ~

$ git clone git://git.linux-nfs.org/projects/mora/nfstest.git

The tests can run without installation, just set the python path

environment variable:

$ export PYTHONPATH=~/nfstest

$ cd nfstest/test

$ ./nfstest_pnfs --help

Or install to standard python site-packages and executable directories:

$ cd ~/nfstest

$ sudo python setup.py install

All manual pages are available

$ man nfstest

Run tests:

$ nfstest_pnfs --help

Setup

Make sure user running the tests can run commands using 'sudo' without the need for a password.
Make sure user running the tests can run commands remotely using 'ssh' without the need for a password. This is only needed for tests which require multiple clients.
Create the mount point specified by the --mtpoint (default: /mnt/t) option on all the clients:

$ sudo mkdir /mnt/t

$ sudo chmod 777 /mnt/t

Examples

nfstest_pnfs

The only required option is --server

$ nfstest_pnfs --server 192.168.0.11

nfstest_cache

Required options are --server and --client

$ nfstest_cache --server 192.168.0.11 --client 192.168.0.20

Testing with different values of --acmin and --acmax (this takes a long time)

$ nfstest_cache --server 192.168.0.11 --client 192.168.0.20 --acmin 10,20 --acmax 20,30,60,80

nfstest_delegation

The only required option is --server but only the basic delegation tests will

be run. In order to run the recall tests the --client option must be used

$ nfstest_delegation --server 192.168.0.11 --client 192.168.0.20

nfstest_dio

The only required option is --server

$ nfstest_dio --server 192.168.0.11

nfstest_posix

The only required option is --server

$ nfstest_posix --server 192.168.0.11