What is Virtualization?
Virtualization is a general and ambiguous term that
typically means to run multiple instances of something inside something that
was intended to only run a single instance.
How do we get virtualization?
Well there is no. of options available for this, but
VMware, Citrix and Microsoft are front runners in domain. Here are the products
from above for the same.
- VMware ESX and VMware server
- Citrix Xen
- Microsoft Hyper-V
VMware Server:
VMware Server is a free
virtualization product for Microsoft Windows and Linux servers. It enables you
to quickly provision new server capacity or server consolidation by
partitioning a Physical server into multiple virtual machines. It is meant for
those businesses who want to optimize use of their technology assets using
virtualization.
Technology
behind VMware Server:
- Hypervisor – 2 (Hosted Architecture)
What is Hosted Architecture?
Hosted architecture is
where your virtualization software is installed as an application onto the
pre-existing host operating system. This means that your virtualization layer
relies on your host operating system for device support and physical resource
management. VMware Server is a good example of a hosted architecture.
Hardware and Software support:
- Any standard x86 compatible or x-86-64compatible personal
computer
- A wide variety of
Windows, Linux, Solaris, and other guest operating systems,
Including
64-bit operating systems
- Two-way Virtual SMP
- Intel
Virtualization Technology (Intel VT)
- AMD-Virtualization
(AMT-V)
Where VMware Server does fits for
your environment?
VMware
server suits the requirements and demands of small and medium scale business
with non-mission critical processes. It can provide following options to the
business resources.
- Virtual
Machines for software development:
- A
common environment matching in both configuration and tools for your
entire team
- Quick
rollout of new environments and tools
- Archive
of entire development environments for major projects
- Virtual
Machines for software testing:
- Platform Testing with Snapshots
- Platform Testing with Persistent and Non-persistent
Disks
- Virtual
Machines for Post-release and Application-Maintenance.
- It can create base image for
you development environment
- Archive of the development team’s
virtual machines used during the development phase
- Rapid
platform availability for quick support tasks and bug investigation
- Run Windows,
Linux, and other operating systems and applications without
Software conflicts.
- Move virtual
machines from one physical host to another without having to
Reconfigure them.
Features of VMware Server:
- Web-Based Interface
Use VMware Infrastructure Web
Access (VI Web Access) to perform host and virtual machine configuration for
VMware Server 2.0.
- Create, configure,
and delete virtual machines
- Add and remove
virtual machines from the inventory
- Perform power
operations (start, stop, reset, suspend, and resume) on virtual Machines
- Monitor the
operation of virtual machines
- Generate a Web
shortcut to customize the VI Web Access user interface for users, with the
option to limit their view to the console or a single virtual machine
- Generate a VMware Remote Console desktop
shortcut that allows virtual machine users to interact directly with the
guest operating system outside of a Web browser
- Configure
host-wide VMware Server settings
- VMware Remote Console
VMware Remote Console
enables you to interact with the guest operating system
running in a virtual
machine. You can run VMware Remote Console on the host or a remote client
system. After you install it as a Web browser add-on from VIWeb Access, VMware
Remote Console can run independently from VIWeb Access.
VMware Remote Console
also allows you to connect and disconnect client CD/DVD
and floppy devices.
- Memory Support
The maximum amount of
memory that can be allocated per virtual machine is
8GB. The amount of
memory that can be used by all virtual machines combined is limited only by the
amount of memory on the host computer.
- Number of Network Adapters Supported
It can support total of 10 network
adapters for a virtual machine.
- Quiesced Backups of Virtual Machines on
Windows
On Windows hosts, you can enable
the VMware VSS Writer, which uses snapshots to
maintain the data integrity of
applications running inside the virtual machine when
you take backups.
- Support for High-Speed USB 2.0 Devices
If the guest operating
system has the appropriate USB 2.0 device drivers, you can use peripherals that
require high-speed performance, such as speakers, webcams,
next-generation
printers and scanners, fast storage devices, MP3 players, DVD-RW
drives, and
high-capacity CD-ROM jukeboxes.
Besides
above there are few more such as
·
Additional host operating system support
·
Additional guest operating system support
·
improved 64 bit guest support
·
64 bit sound driver
·
Native 64 bit support on linux
·
Improved VIX-API
·
VMCI socket interface
Bottlenecks:
- It puts more of
your client's eggs in one basket. If the host machine breaks or needs to
be taken offline, several virtual servers will go down.
- Applications like
databases that require a lot of disk activity. The prevailing wisdom is
that databases should still run on dedicated physical servers.
- Time-sensitive
applications like Voice
over IP (VoIP) may also be poor candidates for virtualization.
- Virtual Machine
overload: Application that are low I/O intensive and low utilization are
best candidates for virtualization but need to put restriction on no. of
virtual machines that can be handled with ease on physical server.
VMware Server at a glance:
Architecture
|
Hosted
|
OS Requirements
|
Windows
or Linux
|
Typical Use Cases
|
Test
& Dev, Production
|
Dedicated Server Required
|
No
|
Centralized Management Option
|
No
|
Ease of Use
|
High
|
Performance
|
Good
|
ESX Server
ESX Server is
VMware’s flagship enterprise server virtualization platform. It comes in
two versions – ESX Server and ESXi Server where the latter has no service
console and is the thinnest version available. ESX Server has many optional
features like VMotion and VMHA and some built-in features like the VMFS file
system. Most end users purchase VMware ESX Server with some set of
optional features in a package called VMware Infrastructure. ESX Server is
managed by the VMware Infrastructure Client. Its centralized management
platform is called Virtual
Center.
Figure 1: ESX
server in Enterprise
(Virtual infrastructure)
What is the need of ESX Server?
If
you are an idealist then ESX is just for you. It possesses best approaches to
adopt the hardware abstraction and most effective usage of your resources
through vast available tools and services so that you can maximize your
infrastructure efficiency, reducing operational cost by providing cost
effective business continuity.
Technology behind ESX:
·
Hypervisor – 1 (Bare Metal)
Bare
Metal means no OS is required because it has its own kernel derived from linux
withit provides greater resources for the virtual machines, decreased cost of
licensing and increased utilization of servers.
Where ESX server does fit for your
environment?
As ESX is enterprise wide solution
for virtualization to adopt effective hardware abstraction, it best suits for
large enterprises with enormous resources.
Hardware and Software support with
Features for ESX:
Architecture:
- Bare-metal architecture: VMware
ESX inserts a robust virtualization layer directly on the server hardware
for near-native virtual machine performance, reliability and scalability.
Fig:
Hypervisor (Baremetal)
- Small Footprint: VMware ESXi’s 32MB disk footprint
is a fraction of the size of a general purpose operating system, reducing
complexity and providing unmatched security and reliability.
- Server Integration: VMware ESXi is available
built into server hardware as an embedded component, simplifying and
speeding deployment of virtualization.
- CPU virtualization: Increase server
utilization without the risk of critical services being starved for CPU
resources. VMware ESX uses intelligent process scheduling and load
balancing across available processors to manage the execution of virtual
machine processing.
- Storage in ESX Server: Leverage
high performance shared storage to centralize virtual machine file storage
for greater manageability, flexibility and availability.
- Virtual disk files: Add
or delete a VMware ESX server from a VMFS volume without pausing or
halting the processing of other instances of VMware ESX
- VMFS cluster file system: Leverage
high performance shared storage to centralize virtual machine file
storage for greater manageability, flexibility and availability
- Logical volume manager: Manage the
interaction between the physical storage arrays and VMFS with flexibility
and reliability
- Raw device mapping: Optionally,
map SAN LUNs directly to a virtual machine in order to enable application
clustering and array-based snapshot technology while profiting from the
manageability benefits of VMFS
- Fiber Channel HBA consolidation: Share
expensive storage network components across many virtual machines while
maintaining hardware fault tolerance
- Write-through I/O: Ensure precise
recovery of virtual machines in the event of server failure.
Write-through I/O enables virtual machines to have the same recovery
characteristics as a physical system running the same operating system.
- Boot from SAN: Run VMware ESX
installations on diskless configurations of blade and rack mount servers
by booting from SAN. Simplify backups and disaster recovery by
eliminating the need to separately backup local attached server disks
VMFS: (Virtual Machine File
System)
VMware Virtual Machine File System is a high performance cluster file system
which provides storage virtualization that is optimized for virtual machines.
Each virtual machine is encapsulated in a small set of files; and VMFS is the
default storage management interface for these files on physical SCSI disks and
partitions.
Fig: VMFS allows
sharing of storage for multiple ESX servers
Features of VMFS:
The technical features
of VMFS that make it suitable for use in a virtual environment include:
1. Automated file system
with hierarchical directory structure
2. Optimization for
virtual machines in a clustered environment
3. Lock management and
distributed logical volume management
4. Dynamic datastore
expansion by spanning multiple storage extents
5. Clustered file system
with journal logging for fast recovery
6. Encapsulation of the
entire virtual machine state in a single directory
Benefits of VMFS:
1. Automated Cluster File System Capability
2. Optimizes VM Access
3. Encapsulates the Entire VM State in a Single Directory
4. Simplifies Provisioning and Administration of VMs
5. Provides Distributed Infrastructure Services for Multi-ESX Servers
6. Facilitates Dynamic Growth
7. Intelligent Cluster Volume Management
8. Enables HA with Lower Management Overhead
9. Simplifies Disaster Recovery
VMFS V/S other file systems:
Conventional file systems allow
only one server to have read-write access to the same file at a given time. In
contrast, VMFS is a cluster file system that leverages shared storage to allow
multiple instances of ESX Server concurrent read and write access to the same
storage resources. VMFS also has distributed journaling to allow fast and
resilient recovery across these multi-server resource pools.
On-disk locking in VMFS ensures
that a virtual machine is not powered on by multiple installations of ESX
Server at the same time. With VMware HA enabled, if a server fails the on-disk
lock for each virtual machine is released, allowing the virtual machine to be
restarted on other physical servers. Moreover, VMFS provides the VM snapshot
capabilities so necessary for disaster recovery, and is the interface which
VMware Consolidated Backup (VCB) leverages to provide proxy backup of virtual
environments.
VMFS does not have every feature
found today in other CFS and CVM systems. However there is no other CFS/CVM
that provides the capabilities of VMFS. Its distributed locking methods forge
the link between the VM and the underlying storage resources in a manner that
no other CFS or CVM can equal. The unique capabilities of VMFS allow VMs to join
a cluster seamlessly, with no management overhead.
- Networking in ESX Server: Network
virtual machines like physical machines. Build complex networks within a
single VMware ESX server or across multiple installations of VMware ESX
for production deployments or development and testing purposes.
·
Virtual NICs: Configure
each virtual machine with one or more virtual NICs. Each of those network
interfaces can have its own IP address and even its own MAC address. As a
result, virtual machines are indistinguishable from physical machines from a
networking standpoint
·
Virtual switches: Create a
simulated network within a VMware ESX server with virtual switches that connect
virtual machines.
·
Expanded port
configuration policies: Simplify port configuration by utilizing a
single configuration object across large groups of ports. The configuration
object specifies all information needed to enable a port: NIC teaming policy
(now per port instead of per virtual switch), VLAN tagging, Layer 2 security,
and traffic shaping.
·
VLAN: Overlay a
logical LAN on top of physical LANs to isolate network traffic for security and
load segregation purposes. VMware ESX VLANs are compatible with standard VLAN
implementations from other vendors. Modify network configurations without
having to change actual cabling and switch setups. VLANs keep broadcast traffic
limited to the VLAN, reducing the network load of broadcast packets on other switches
and network segments.
Performance and Scalability:
VMware
ESX delivers unparalleled performance and scalability. With VMware ESX,
even the most resource intensive production applications such as databases, ERP
and CRM can be virtualized.
- Enhanced virtual machine performance: Benefit
from better virtual machine performance in VMware ESX. Performance
improvements have been achieved through:
- Networking performance optimization: Reduce the CPU
overhead associated with processing network i/
- Support for hardware nested page tables: Optimize memory
translation time between guest operating systems and physical memory
- Support for large memory pages: Improve memory
access efficiency for guest operating systems and the Hypervisor
- Support for Para
virtualized Linux guest operating systems (Linux kernel 2.6.21
onwards). Run higher levels of performance through virtualization-aware
operating systems
- Advanced memory management:
·
RAM over-commitment: Increase
memory utilization by configuring virtual machine memory that safely exceeds
the physical server memory. For example, the sum of the memory of all virtual
machines running on a server with 8GB physical memory can be 16GB
·
Transparent page
sharing: Utilize
available memory more efficiently by storing memory pages identical across
multiple virtual machines only once. For example, if several virtual machines
are running Windows Server 2003, they will have many identical memory pages.
Transparent page sharing consolidates those identical pages into a single
memory location.
·
Memory ballooning: Shift
memory dynamically from idle virtual machines to active ones. Memory ballooning
artificially induces memory pressure within idle virtual machines, forcing them
to use their own paging areas and release memory for active virtual machines.
- Improved power management: Lower
the data center utility bill with improved power management. VMware ESX
enters a low power “halt” state when a CPU is not scheduled.
- 4-Way Virtual SMP(Symmetric multiple
processor): Enable a single virtual machine to use up to four
physical processors simultaneously. VMware ESX extends this unique feature
from two to four processors. With 4-way Virtual SMP even the most
processor intensive software applications like databases and messaging
servers can be virtualized.
- 64GB RAM for virtual machines: Run the
most memory-intensive workloads in virtual machines with a memory limit
extended to 64GB.
- Support for powerful physical server systems: Take
advantage of very large server systems with up to 32 logical CPUs and
256GB RAM for large scale server consolidation and DR projects.
- Support for up to 128 powered-on virtual
machines: Take advantage of very large server systems for
enterprise-class server consolidation and containment with support for up
to 128 powered on virtual machines on a single server.
- Flexible virtual switches: Scale
up to handle more virtual machines. Virtual switches can be created with
any number of ports from 8 to 1016, and up to 248 virtual switches are
supported per host.
- Wake-on LAN: Enable higher
consolidation ratios by allowing virtual machines to go on stand-by mode
when not used.
Interoperability:
VMware
ESX is the only virtualization platform optimized, rigorously tested and
certified across the complete IT stack of servers, storage, operating systems,
and software applications allowing for enterprise-wide standardization.
- Hardware: VMware ESX has
been certified with industry-leading rack, tower and blade servers from
Dell, Fujitsu Siemens, HP, IBM, NEC, Sun Microsystems and Unisys as well
as servers that conform to Intel white-box standard specifications.
VMware ESXi is integrated into
server hardware guaranteeing that virtualization works out of the box.
- Storage: VMware ESX is
certified with a wide range of storage systems from, Dell, EMC,
EqualLogic, Fujitsu, Fujitsu Siemens, HP, Hitachi Data Systems, IBM, NEC,
Network Appliance, StorageTek, Sun Microsystems and 3PAR and many other
vendors.
- Heterogeneous storage arrays: Utilize
a wide variety of heterogeneous storage devices in the same VMFS volume
- NAS and iSCSI SAN support: By supporting
lower-cost, more easily managed shared storage, VMware ESX further
reduces total cost of ownership of IT environments. Advanced VMware
Infrastructure features like VMotion and VMware HA are fully supported
with NAS and iSCSI environments
- 4GB Fibre Channel SAN support: Centralize
management and configuration of all VMware ESX servers in VirtualCenter.
- Local SATA storage support: Use select
servers with local SATA storage to further lower total cost of ownership
while consolidating workloads
- Networking: Use high performance
networking such as 10 Gig E and Infiniband with VMware ESX 3.5
and VMware ESXi 3.5 for the most network intensive workloads
- Operating systems: Run any software
application in VMware virtual machines.
·
64-bit guest operating system suppor
·
Solaris 10 operating system suppor
·
Windows Vista operating system support
·
Ubuntu guest operating system support
- Software applications with third
party systems management products through Web services APIs provided by
the VMware Infrastructure SDK.
- Support for other virtual machine formats: VMware
ESX can run virtual machines created in non-VMware formats. Using the free
VMware Virtual Machine Importer users can run Microsoft® Virtual Server
and Virtual PC, and Symantec® LiveState Recovery virtual machines in
VMware ESX.
Management:
- Remote Command Line Interface. Manage VMware
ESXi through a remote execution environment that can run VMware ESX
command scripts.
- Advanced manageability and usability features: VMware
ESX enables management of entire virtualized IT environment.
- SMI-S-Compliant Management Interfaces: Monitor
virtual storage using any standard SMI-S-aware storage management tool.
- Virtual Infrastructure Client: Manage
VMware ESX, virtual machines, and (optionally) VMware vCenter Server with
a common user interface.
- Virtual Infrastructure Web Access: Manage
VMware ESX with simple Web interface (formerly known as the
Management User Interface, or MUI).
- Virtual machine shortcuts: Enable
self-help for end users with direct access to virtual machines through a
Web browser.
- Remote devices: Install software
in a virtual machine running on a server from the CD-ROM of a desktop
without leaving your desk.
- Agent-less Hardware Management with CIM: The Common
Information Model (CIM) provides a protocol for monitoring hardware health
and status through VirtualCenter or CIM-compatible 3rd party tools.
Fig: ESX-Virtual
Center
Resource Optimization:
It defines advanced resource
allocation policies for virtual machines to improve service levels to software
applications. Establish minimum, maximum, and proportional resource shares for
CPU, memory, disk and network bandwidth. Modify allocations while virtual
machines are running. Enable applications to dynamically acquire more resources
to accommodate peak performance.
- CPU capacity prioritization: CPU capacity is
assigned to virtual machines on a “fair share” basis and CPU resource
controls also allow an absolute minimum level of CPU capacity to be
provided to critical virtual machines
- Storage I/O traffic prioritization: Ensure
that critical virtual machines receive priority access to storage devices.
I/O traffic from virtual machines to disk can be prioritized on a “fair
share” basis.
- Network Traffic Shaper: Ensure
that critical virtual machines receive priority access to network
bandwidth. Network traffic from virtual machines can be prioritized on a
“fair share” basis. Network Traffic Shaper manages virtual machine network
traffic to meet peak bandwidth, average bandwidth and burst size
constraints.
- Resource Pool: Aggregate
collections of hardware resources virtualized by VMware ESX into unified
logical resources that can be allocated to virtual machines on-demand.
Resource pools increase flexibility and hardware utilization.
Security:
- Compatibility with SAN security practices: Enforce
security policies with LUN zoning and LUN masking.
- VLAN tagging: Enhance network
security by tagging and filtering network traffic on VLANs. Limit the
scope of broadcast domains.
- Layer 2 network security policies: Enforce
security for virtual machines at the Ethernet layer. Disallow promiscuous
mode sniffing of network traffic, MAC address changes, and forged source
MAC transmits.
ESX VCB(VMware Consolidated
backup):
VCB is a group of Windows
command line utilities, installed on a Windows system, that has SAN
connectivity to the ESX Server VMFS file system. With VCB, you can perform file
level or image level backups and restores of the VM guests, back to the VCB
server. FFf
Fig: ESX-VCB
ESX-Vmotion:
VM guests are
able to move from one ESX Server to another with no downtime for the users.
What is required is a shared SAN storage system between the ESX Servers and a
VMotion license.
Fig: ESX-Vmotion
ESX at a
glance:
Architecture
|
Hypervisor
|
OS Requirements
|
None
|
Typical Use Cases
|
Production,
Test & Dev
|
Dedicated Server Required
|
Yes
|
Centralized Management Option
|
Yes
|
Ease of Use
|
High
|
Performance
|
Best
|
Comparison between VMware ESX
Server and VMware Server using V-Mark:
Running
VMmark using ESX Server on an HP DL585 with four 2.2GHz dual-core processors
and then ran VMmark on VMware Server using a similar HP DL585 with four 2.4 GHz
dual-core processors. The result is as below:
These
results show that ESX Server not only achieves higher throughput than VMware Server
for a single VMmark tile (6 workload VMs) but also exhibits better scalability
when a second tile is added