Wpars versus Lpars- A quick comparision

While Lpars and Wpars are both virtualization features of IBM Power systems , there are inherently differences which do reside between Lpars and Wpars.

I would say a major difference which exist between Lpars and Wpars is that Lpars are hardware based virtualization approach while Wpars are software based approach.
WPARs are lightweight and quicker to install, because they share many of the file systems and resources of the global AIX system in which they reside.
On the other hand While using an LPAR requires you to install an entire operating system, creation of system WPARs only installs private copies of a few file systems, and application WPARs share even more of the global system's resources. As a result, a WPAR can be created in just a few minutes without installation media. Ongoing administration and maintenance of WPARs should be simpler—fewer AIX licenses might be required, and you don’t have to install fixes and updates on so many virtual systems. There is a command for synchronizing the filesets of a WPAR with the corresponding filesets on the global system, so you have the choice of propagating AIX fixes to WPARs or continuing to run with the current versions of system files.

While LPARs offer a significantly higher degree of workload isolation, WPARs might provide "good enough" isolation for your particular workloads, especially temporary ones such as development or test environments. Similarly, with LPARs, you can achieve a greater degree of control over the usage of resources—by allocating entire processors or precise fractions of processors to an LPAR, for example. With WPARs, you don’t have such fine control over resource allocations, but you can allocate target shares or percentages of CPU utilization to a WPAR (if have used the AIX Workload Manager, you will find the share and percentage resource allocation scheme familiar). Similar differences exist for the allocation of memory, number of processes, and other resources.

Unix Versus Windows- Which OS to choose?

1.Availability :

UNIX:UNIX operating system and Kernel, by design are free from viruses, worms and malicious system threats including spying software

WINDOWS:Windows Operating system inherently capable of being attacked by large number of viruses, worms and Trojan horses. These are potential threats to systems stability and may crash even a powerful production server running on windows or even corrupt the production data.


Additional Comments:
I
According to Dr. Nic Peeling and Dr Julian Satchell's Analysis of the Impact of Open Source Software
Windo("There are about 60,000 viruses known for Windows, 40 or so for the Macintosh, about 5 for commercial Unix versions, and perhaps 40 for Linux. Most of the Windows viruses are not important, but many hundreds have caused widespread damage. Two or three of the Macintosh viruses were widespread enough to be of importance. None of the Unix or Linux viruses became widespread - most were confined to the specific files."


2. Downtime Costs:

UNIX:Down time costs are low in case of UNIX.

WINDOWS:Downtime costs are high in case of windows OS.


Additional Comments:
Windows Server Downtime Costs Companies two to three times as much as Linux/UNIX server downtime. This is not due to any inherent flaws in the Windows server OS, but rather reflects the crucial nature of the data and applications running on Windows servers. Windows application servers racked up the biggest downtime expenses: $5,624 per hour versus $1,168 in hourly downtime costs for comparable Linux
Source :
http://www.iaps.com/Linux-Windows-TCO-Survey-2005.04.html



3. Stability:

UNIX:Unix is more stable operating system and it does not go down as often as Windows does, therefore requires less administration and maintenance

WINDOWS:Blue screen is a common windows dilemma. System crashes are very common due to many possible reasons including hardware and software.

Additional Comments:

According to latest servers reliability survey 2008 http://www.iaps.com/2008-server-reliability-survey.html,
UNIX has a superior edge over windows in terms of reliability and availability.. According to same survey report, IBM AIX is leading UNIX variant in terms of less down time, with HPUX as number two.


4. Performance:

UNIX:Unix possesses much greater processing power than Windows.

WINDOWS:Windows Operating system running on CICS architecture machines and is bit slower. Moreover, recent Microsoft attempts to increase OS hardening have also reduced windows performance little bit.

Most of leading UNIX servers are RISC architecture based and therefore much performance oriented as compared to Windows servers.


5.System Upgrades:

UNIX:Software upgrades are straightforward and does not require any prerequisites. Moreover time required for patch management is not high

WINDOWS:Software upgrades from Microsoft often require the user to purchase new or more hardware or prerequisite software. Time required for patch management is quite high due to large number of patches released by Microsoft.

6. Security

UNIX:Unix has greater built-in security and permissions features than Windows


ADDITIONAL COMMENTS:For example, on a Windows system, programs installed by a non-Administrative user can still add DLLs and other system files that can be run at a level of permission that damages the system itself. Even worse, the collection of files on a Windows system - the operating system, the applications, and the user data - can't be kept apart from each other. Things are intermingled to a degree that makes it unlikely that they will ever be satisfactorily sorted out in any sensibly secure fashion.


7.Manageability:

UNIX:UNIX system administration is available through command line as well as through GUI ( KDE, XWINDOWS, GNOME)

WINDOWS:Windows administration is more users friendly and available through GUI.


Traditionally speaking UNIX is considered as command line text editor oriented operating system, however availability of XWINDOWS and KNOME etc has changed the perspective and UNIX administration is far easy as compared to what it was ten years ago. Still, in terms of user friendliness , Windows have an edge.

8.System Recovery:

UNIX:System recovery time is slightly higher in case of UNIX systems

WINDOWS:System recovery is faster in windows systems

According to a survey, Linux Servers Take Nearly Four Hours or 30% Longer to Recover from a Security Attack than a similar Windows Server. The survey respondents revealed that it took them 17 hours on average for their Linux servers to recover from a security attack compared to an average recovery time of 13.2 hours for Windows Servers.
Source: http://www.iaps.com/Linux-Windows-TCO-Survey-2005.04.html

9. Virtualization:

UNIX:Virtualization is built-in for most of latest commercially available UNIX variants. AIX for example supports Lpars, Micropartitioning, PLM and WPARS for virtualization.

WINDOWS:Virtualization is available through third party tools like VMware, however possesses certain limitations.

SAN Versus NAS

At first glance NAS and SAN might seem almost identical, and in fact many times either will work in a given situation. After all, both NAS and SAN generally use RAID connected to a network, which then are backed up onto tape. However, there are differences -- important differences -- that can seriously affect the way your data is utilized. For a quick introduction to the technology, take a look at the diagrams below.

Wires and Protocols
Most people focus on the wires, but the difference in protocols is actually the most important factor. For instance, one common argument is that SCSI is faster than ethernet and is therefore better. Why? Mainly, people will say the TCP/IP overhead cuts the efficiency of data transfer. So a Gigabit Ethernet gives you throughputs of 60-80 Mbps rather than 100Mbps.

But consider this: the next version of SCSI (due date ??) will double the speed; the next version of ethernet (available in beta now) will multiply the speed by a factor of 10. Which will be faster? Even with overhead? It's something to consider.

The Wires
--NAS uses TCP/IP Networks: Ethernet, FDDI, ATM (perhaps TCP/IP over Fibre Channel someday)
--SAN uses Fibre Channel

The Protocols
--NAS uses TCP/IP and NFS/CIFS/HTTP
--SAN uses Encapsulated SCSI

More Differences
NAS		SAN
Almost any machine that can connect to the LAN (or is interconnected to the LAN through a WAN) can use NFS, CIFS or HTTP protocol to connect to a NAS and share files.		Only server class devices with SCSI Fibre Channel can connect to the SAN. The Fibre Channel of the SAN has a limit of around 10km at best
A NAS identifies data by file name and byte offsets, transfers file data or file meta-data (file's owner, permissions, creation data, etc.), and handles security, user authentication, file locking		A SAN addresses data by disk block number and transfers raw disk blocks.
A NAS allows greater sharing of information especially between disparate operating systems such as Unix and NT.		File Sharing is operating system dependent and does not exist in many operating systems.
File System managed by NAS head unit		File System managed by servers
Backups and mirrors (utilizing features like NetApp's Snapshots) are done on files, not blocks, for a savings in bandwidth and time. A Snapshot can be tiny compared to its source volume.		Backups and mirrors require a block by block copy, even if blocks are empty. A mirror machine must be equal to or greater in capacity compared to the source volume.