Fahmi Rizwansyah says:
Selamat pagi sobat semua. Ini aku tulis pada tanggal 1 Februari 2009 pukul 1:37 am.
Semoga semua sobat bloggerous sehat wal afiyat, terus giat berkarya dan makin cinta akan persahabatan.
Mulai hari ini aku launching project baru di www.lagunabiru.com, sebagai wadah berekspresi berikutnya. Semua yang ingin berpartisipasi akan aku terima dengan terbuka.
Love your visiting, your friendship and your posting...
Cheers, frizzy.
Lawyer Responsibilities
Fahmi Rizwansyah says:
Responsibilities
In most countries, particularly civil law countries, there has been a tradition of giving many legal tasks to a variety of civil law notaries, clerks, and scriveners. These countries do not have "lawyers" in the American sense, insofar as that term refers to a single type of general-purpose legal services provider; rather, their legal professions consist of a large number of different kinds of law-trained persons, known as jurists, of which only some are advocates who are licensed to practice in the courts. It is difficult to formulate accurate generalizations that cover all the countries with multiple legal professions, because each country has traditionally had its own peculiar method of dividing up legal work among all its different types of legal professionals.
Notably, England, the mother of the common law jurisdictions, emerged from the Dark Ages with similar complexity in its legal professions, but then evolved by the 19th century to a single dichotomy between barristers and solicitors. An equivalent dichotomy developed between advocates and procurators in some civil law countries, though these two types did not always monopolize the practice of law as much as barristers and solicitors, in that they always coexisted with civil law notaries.
Several countries that originally had two or more legal professions have since fused or united their professions into a single type of lawyer. Most countries in this category are common law countries, though France, a civil law country, merged together its jurists in 1990 and 1991 in response to Anglo-American competition. In countries with fused professions, a lawyer is usually permitted to carry out all or nearly all the responsibilities listed below.
Oral argument in the courts
Arguing a client's case before a judge or jury in a court of law is the traditional province of the barrister in England, and of advocates in some civil law jurisdictions. However, the boundary between barristers and solicitors has evolved. In England today, the barrister monopoly covers only appellate courts, and barristers must compete directly with solicitors in many trial courts. In countries like the United States that have fused legal professions, there are trial lawyers who specialize in trying cases in court, but trial lawyers do not have a de jure monopoly like barristers.
In some countries, litigants have the option of arguing pro se, or on their own behalf. It is common for litigants to appear unrepresented before certain courts like small claims courts; indeed, many such courts do not allow lawyers to speak for their clients, in an effort to save money for all participants in a small case. In other countries, like Venezuela, no one may appear before a judge unless represented by a lawyer. The advantage of the latter regime is that lawyers are familiar with the court's customs and procedures, and make the legal system more efficient for all involved. Unrepresented parties often damage their own credibility or slow the court down as a result of their inexperience.
Research and drafting of court papers
Often, lawyers brief a court in writing on the issues in a case before the issues can be orally argued. They may have to perform extensive research into relevant facts and law while drafting legal papers and preparing for oral argument.
In England, the usual division of labour is that a solicitor will obtain the facts of the case from the client and then brief a barrister (usually in writing). The barrister then researches and drafts the necessary court pleadings (which will be filed and served by the solicitor) and orally argues the case.
Advocacy (written and oral) in administrative hearings
In most developed countries, the legislature has granted original jurisdiction over highly technical matters to executive branch administrative agencies which oversee such things. As a result, some lawyers have become specialists in administrative law. In a few countries, there is a special category of jurists with a monopoly over this form of advocacy; for example, France formerly had conseil juridiques (who were merged into the main legal profession in 1991). In other countries, like the United States, lawyers have been effectively barred by statute from certain types of administrative hearings in order to preserve their informality.
Client intake and counseling (with regard to pending litigation)
An important aspect of a lawyer's job is developing and managing relationships with clients (or the client's employees, if the lawyer works in-house for a government or corporation). The client-lawyer relationship often begins with an intake interview where the lawyer gets to know the client personally, discovers the facts of the client's case, clarifies what the client wants to accomplish, shapes the client's expectations as to what actually can be accomplished, begins to develop various claims or defenses, and explains his or her fees to the client.
In England, only solicitors were traditionally in direct contact with the client. The solicitor retained a barrister if one was necessary and acted as an intermediary between the barrister and the client. In most cases a barrister would be obliged, under what is known as the "cab rank rule", to accept instructions for a case in an area in which they held themselves out as practising, at a court at which they normally appeared and at their usual rates.
Legal advice
Legal advice is the application of abstract principles of law to the concrete facts of the client's case in order to advise the client about what they should do next. In many countries, only a properly licensed lawyer may provide legal advice to clients for good consideration, even if no lawsuit is contemplated or is in progress. Therefore, even conveyancers and corporate in-house counsel must first get a license to practice, though they may actually spend very little of their careers in court. Failure to obey such a rule is the crime of unauthorized practice of law.
In other countries, jurists who hold law degrees are allowed to provide legal advice to individuals or to corporations, and it is irrelevant if they lack a license and cannot appear in court. Some countries go further; in England and Wales, there is no general prohibition on the giving of legal advice. Sometimes civil law notaries are allowed to give legal advice, as in Belgium. In many countries, non-jurist accountants may provide what is technically legal advice in tax and accounting matters.
Protecting intellectual property
In virtually all countries, patents, trademarks, industrial designs and other forms of intellectual property must be formally registered with a government agency in order to receive maximum protection under the law. The division of such work among lawyers, licensed non-lawyer jurists/agents, and ordinary clerks or scriveners varies greatly from one country to the next.
Negotiating and drafting contracts
In some countries, the negotiating and drafting of contracts is considered to be similar to the provision of legal advice, so that it is subject to the licensing requirement explained above. In others, jurists or notaries may negotiate or draft contracts.
Lawyers in some civil law countries traditionally deprecated "transactional law" or "business law" as beneath them. French law firms developed transactional departments only in the 1990s when they started to lose business to international firms based in the United States and the United Kingdom (where solicitors have always done transactional work).
Conveyancing
Conveyancing is the drafting of the documents necessary for the transfer of real property, such as deeds and mortgages. In some jurisdictions, all real estate transactions must be carried out by a lawyer (or a solicitor where that distinction still exists). Such a monopoly is quite valuable from the lawyer's point of view; historically, conveyancing accounted for about half of English solicitors' income (though this has since changed), and a 1978 study showed that conveyancing "accounts for as much as 80 percent of solicitor-client contact in New South Wales." In most common law jurisdictions outside of the United States, this monopoly arose from an 1804 law that was introduced by William Pitt the Younger as a quid pro quo for the raising of fees on the certification of legal professionals such as barristers, solicitors, attorneys and notaries.
In others, the use of a lawyer is optional and banks, title companies, or realtors may be used instead. In some civil law jurisdictions, real estate transactions are handled by civil law notaries. In England and Wales a special class of legal professional–the licensed conveyancer–is also allowed to carry out conveyancing services for reward.
Carrying out the intent of the deceased
In many countries, only lawyers have the legal authority to do drafting of wills, trusts, and any other documents that ensure the efficient disposition of a person's property after death. In some civil law countries this responsibility is handled by civil law notaries.
In the United States, the estates of the deceased must be administered by a court through probate. American lawyers have a profitable monopoly on dispensing advice about probate law (which has been heavily criticized).
Prosecution and defense of criminal suspects
In many civil law countries, prosecutors are trained and employed as part of the judiciary; they are law-trained jurists, but may not necessarily be lawyers in the sense that the word is used in the common law world. In common law countries, prosecutors are usually lawyers holding regular licenses who simply happen to work for the government office that files criminal charges against suspects. Criminal defense lawyers specialize in the defense of those charged with any crimes.
taken from Wikipedia.
Cheers, frizzy.
Responsibilities
In most countries, particularly civil law countries, there has been a tradition of giving many legal tasks to a variety of civil law notaries, clerks, and scriveners. These countries do not have "lawyers" in the American sense, insofar as that term refers to a single type of general-purpose legal services provider; rather, their legal professions consist of a large number of different kinds of law-trained persons, known as jurists, of which only some are advocates who are licensed to practice in the courts. It is difficult to formulate accurate generalizations that cover all the countries with multiple legal professions, because each country has traditionally had its own peculiar method of dividing up legal work among all its different types of legal professionals.
Notably, England, the mother of the common law jurisdictions, emerged from the Dark Ages with similar complexity in its legal professions, but then evolved by the 19th century to a single dichotomy between barristers and solicitors. An equivalent dichotomy developed between advocates and procurators in some civil law countries, though these two types did not always monopolize the practice of law as much as barristers and solicitors, in that they always coexisted with civil law notaries.
Several countries that originally had two or more legal professions have since fused or united their professions into a single type of lawyer. Most countries in this category are common law countries, though France, a civil law country, merged together its jurists in 1990 and 1991 in response to Anglo-American competition. In countries with fused professions, a lawyer is usually permitted to carry out all or nearly all the responsibilities listed below.
Oral argument in the courts
Arguing a client's case before a judge or jury in a court of law is the traditional province of the barrister in England, and of advocates in some civil law jurisdictions. However, the boundary between barristers and solicitors has evolved. In England today, the barrister monopoly covers only appellate courts, and barristers must compete directly with solicitors in many trial courts. In countries like the United States that have fused legal professions, there are trial lawyers who specialize in trying cases in court, but trial lawyers do not have a de jure monopoly like barristers.
In some countries, litigants have the option of arguing pro se, or on their own behalf. It is common for litigants to appear unrepresented before certain courts like small claims courts; indeed, many such courts do not allow lawyers to speak for their clients, in an effort to save money for all participants in a small case. In other countries, like Venezuela, no one may appear before a judge unless represented by a lawyer. The advantage of the latter regime is that lawyers are familiar with the court's customs and procedures, and make the legal system more efficient for all involved. Unrepresented parties often damage their own credibility or slow the court down as a result of their inexperience.
Research and drafting of court papers
Often, lawyers brief a court in writing on the issues in a case before the issues can be orally argued. They may have to perform extensive research into relevant facts and law while drafting legal papers and preparing for oral argument.
In England, the usual division of labour is that a solicitor will obtain the facts of the case from the client and then brief a barrister (usually in writing). The barrister then researches and drafts the necessary court pleadings (which will be filed and served by the solicitor) and orally argues the case.
Advocacy (written and oral) in administrative hearings
In most developed countries, the legislature has granted original jurisdiction over highly technical matters to executive branch administrative agencies which oversee such things. As a result, some lawyers have become specialists in administrative law. In a few countries, there is a special category of jurists with a monopoly over this form of advocacy; for example, France formerly had conseil juridiques (who were merged into the main legal profession in 1991). In other countries, like the United States, lawyers have been effectively barred by statute from certain types of administrative hearings in order to preserve their informality.
Client intake and counseling (with regard to pending litigation)
An important aspect of a lawyer's job is developing and managing relationships with clients (or the client's employees, if the lawyer works in-house for a government or corporation). The client-lawyer relationship often begins with an intake interview where the lawyer gets to know the client personally, discovers the facts of the client's case, clarifies what the client wants to accomplish, shapes the client's expectations as to what actually can be accomplished, begins to develop various claims or defenses, and explains his or her fees to the client.
In England, only solicitors were traditionally in direct contact with the client. The solicitor retained a barrister if one was necessary and acted as an intermediary between the barrister and the client. In most cases a barrister would be obliged, under what is known as the "cab rank rule", to accept instructions for a case in an area in which they held themselves out as practising, at a court at which they normally appeared and at their usual rates.
Legal advice
Legal advice is the application of abstract principles of law to the concrete facts of the client's case in order to advise the client about what they should do next. In many countries, only a properly licensed lawyer may provide legal advice to clients for good consideration, even if no lawsuit is contemplated or is in progress. Therefore, even conveyancers and corporate in-house counsel must first get a license to practice, though they may actually spend very little of their careers in court. Failure to obey such a rule is the crime of unauthorized practice of law.
In other countries, jurists who hold law degrees are allowed to provide legal advice to individuals or to corporations, and it is irrelevant if they lack a license and cannot appear in court. Some countries go further; in England and Wales, there is no general prohibition on the giving of legal advice. Sometimes civil law notaries are allowed to give legal advice, as in Belgium. In many countries, non-jurist accountants may provide what is technically legal advice in tax and accounting matters.
Protecting intellectual property
In virtually all countries, patents, trademarks, industrial designs and other forms of intellectual property must be formally registered with a government agency in order to receive maximum protection under the law. The division of such work among lawyers, licensed non-lawyer jurists/agents, and ordinary clerks or scriveners varies greatly from one country to the next.
Negotiating and drafting contracts
In some countries, the negotiating and drafting of contracts is considered to be similar to the provision of legal advice, so that it is subject to the licensing requirement explained above. In others, jurists or notaries may negotiate or draft contracts.
Lawyers in some civil law countries traditionally deprecated "transactional law" or "business law" as beneath them. French law firms developed transactional departments only in the 1990s when they started to lose business to international firms based in the United States and the United Kingdom (where solicitors have always done transactional work).
Conveyancing
Conveyancing is the drafting of the documents necessary for the transfer of real property, such as deeds and mortgages. In some jurisdictions, all real estate transactions must be carried out by a lawyer (or a solicitor where that distinction still exists). Such a monopoly is quite valuable from the lawyer's point of view; historically, conveyancing accounted for about half of English solicitors' income (though this has since changed), and a 1978 study showed that conveyancing "accounts for as much as 80 percent of solicitor-client contact in New South Wales." In most common law jurisdictions outside of the United States, this monopoly arose from an 1804 law that was introduced by William Pitt the Younger as a quid pro quo for the raising of fees on the certification of legal professionals such as barristers, solicitors, attorneys and notaries.
In others, the use of a lawyer is optional and banks, title companies, or realtors may be used instead. In some civil law jurisdictions, real estate transactions are handled by civil law notaries. In England and Wales a special class of legal professional–the licensed conveyancer–is also allowed to carry out conveyancing services for reward.
Carrying out the intent of the deceased
In many countries, only lawyers have the legal authority to do drafting of wills, trusts, and any other documents that ensure the efficient disposition of a person's property after death. In some civil law countries this responsibility is handled by civil law notaries.
In the United States, the estates of the deceased must be administered by a court through probate. American lawyers have a profitable monopoly on dispensing advice about probate law (which has been heavily criticized).
Prosecution and defense of criminal suspects
In many civil law countries, prosecutors are trained and employed as part of the judiciary; they are law-trained jurists, but may not necessarily be lawyers in the sense that the word is used in the common law world. In common law countries, prosecutors are usually lawyers holding regular licenses who simply happen to work for the government office that files criminal charges against suspects. Criminal defense lawyers specialize in the defense of those charged with any crimes.
taken from Wikipedia.
Cheers, frizzy.
Let's be inspired
Fahmi Rizwansyah says:
What Virgin does…
I’m not good at theory. Almost everything I’ve learned, I’ve learned by doing. However, Muhammad’s opinions excite me. They confirm a lot of the gut feelings I’ve developed about business over the years. And topping my list of gut feelings is this: business has to give people enriching, rewarding lives, or it’s simply not worth doing.
I think of our Virgin brand as one of the premier ‘way of life’ brands in the world. Whether you’re in the United States, Australia and New Zealand, Japan, South Africa, India, Europe, Russia, South America or China, the Virgin brand means something. The Virgin brand is about enjoying life to the full. By offering customers excellent value for money in so many areas of their lives, we aim to make them happier.
Most businesses concentrate on one thing, and for the best of reasons: because their founders and leaders care about one thing, above all others, and they want to devote their lives to that thing. They’re not limited in their thinking. They’re focused. The conventional wisdom at business school is that you stick with what you know. Of the top twenty brands in the world, nineteen ply a well-defined trade.
Coca-Cola specialises in soft drinks, Microsoft’s into computers, Nike makes sports shoes and gear. The exception in this list is Virgin – and the fact that we’re worth $5 billion and counting really gets up the noses of people who think they know ‘the rules of business’ (whatever they are). We’re the only one of the top twenty that has diversified into a range of business activities, including airlines, trains, holidays, mobile phones, media – including television, radio and cable – the Internet, financial services and healthcare.
Hopefully what I’ve written here is relevant to your business no matter what sector you are in.
taken from http://entrepreneur.virgin.com/2009/01/05/what-virgin-does/
Cheers, frizzy.
What Virgin does…
I’m not good at theory. Almost everything I’ve learned, I’ve learned by doing. However, Muhammad’s opinions excite me. They confirm a lot of the gut feelings I’ve developed about business over the years. And topping my list of gut feelings is this: business has to give people enriching, rewarding lives, or it’s simply not worth doing.
I think of our Virgin brand as one of the premier ‘way of life’ brands in the world. Whether you’re in the United States, Australia and New Zealand, Japan, South Africa, India, Europe, Russia, South America or China, the Virgin brand means something. The Virgin brand is about enjoying life to the full. By offering customers excellent value for money in so many areas of their lives, we aim to make them happier.
Most businesses concentrate on one thing, and for the best of reasons: because their founders and leaders care about one thing, above all others, and they want to devote their lives to that thing. They’re not limited in their thinking. They’re focused. The conventional wisdom at business school is that you stick with what you know. Of the top twenty brands in the world, nineteen ply a well-defined trade.
Coca-Cola specialises in soft drinks, Microsoft’s into computers, Nike makes sports shoes and gear. The exception in this list is Virgin – and the fact that we’re worth $5 billion and counting really gets up the noses of people who think they know ‘the rules of business’ (whatever they are). We’re the only one of the top twenty that has diversified into a range of business activities, including airlines, trains, holidays, mobile phones, media – including television, radio and cable – the Internet, financial services and healthcare.
Hopefully what I’ve written here is relevant to your business no matter what sector you are in.
taken from http://entrepreneur.virgin.com/2009/01/05/what-virgin-does/
Cheers, frizzy.
Sensasi Seks di Tempat Umum
Fahmi Rizwansyah says:
La Rose Djayasupena - Belanda
Hoi Zev en KoKiers, Untuk sebagian orang seks di muka umum mungkin sangat mengerikan dan memalukan melakukannya, tetapi untuk sebagian orang justru adalah suatu sensasi yang tak ternilai sangat indah dan menyenangkan untuk melakukannya.
Biasanya, kita dengan pasangan, pertama memulainya dengan sekedar ciuman saja sambil berpelukan di muka umum dan tanpa disadari saking enak dan nikmatnya.. ceilee..malah ciuman pun berubah tidak hanya sekedar cap..cup.. cap.. cup..hingga memainkan lidah masing-masing sampai muter dan merem-melek segala, padahal kita saat itu sebenarnya lagi berada di tempat umum, paling orang yang lewat hanya geleng-geleng kepala sambil senyum-senyum.
Di Belanda melakukan hubungan intim sangat mudah di tempat umum atau ruangan terbuka, sensasinya...hhmm.. ehem..ehem..bener - bener mengasyikan dan menyenangkan.
http://community.kompas.com/index.php/read/artikel/2192<--original posting.
Cheers, frizzy.
Virtualization...continue
Fahmi Rizwansyah says:
Following are some (possibly overlapping) representative reasons for and benefits of virtualization.
* Virtual machines can be used to consolidate the workloads of several under-utilized servers to fewer machines, perhaps a single machine (server consolidation). Related benefits (perceived or real, but often cited by vendors) are savings on hardware, environmental costs, management, and administration of the server infrastructure.
* The need to run legacy applications is served well by virtual machines. A legacy application might simply not run on newer hardware and/or operating systems. Even if it does, if may under-utilize the server, so as above, it makes sense to consolidate several applications. This may be difficult without virtualization as such applications are usually not written to co-exist within a single execution environment (consider applications with hard-coded System V IPC keys, as a trivial example).
* Virtual machines can be used to provide secure, isolated sandboxes for running untrusted applications. You could even create such an execution environment dynamically - on the fly - as you download something from the Internet and run it. You can think of creative schemes, such as those involving address obfuscation. Virtualization is an important concept in building secure computing platforms.
* Virtual machines can be used to create operating systems, or execution environments with resource limits, and given the right schedulers, resource guarantees. Partitioning usually goes hand-in-hand with quality of service in the creation of QoS-enabled operating systems.
* Virtual machines can provide the illusion of hardware, or hardware configuration that you do not have (such as SCSI devices, multiple processors, ...) Virtualization can also be used to simulate networks of independent computers.
* Virtual machines can be used to run multiple operating systems simultaneously: different versions, or even entirely different systems, which can be on hot standby. Some such systems may be hard or impossible to run on newer real hardware.
* Virtual machines allow for powerful debugging and performance monitoring. You can put such tools in the virtual machine monitor, for example. Operating systems can be debugged without losing productivity, or setting up more complicated debugging scenarios.
* Virtual machines can isolate what they run, so they provide fault and error containment. You can inject faults proactively into software to study its subsequent behavior.
* Virtual machines make software easier to migrate, thus aiding application and system mobility.
* You can treat application suites as appliances by "packaging" and running each in a virtual machine.
* Virtual machines are great tools for research and academic experiments. Since they provide isolation, they are safer to work with. They encapsulate the entire state of a running system: you can save the state, examine it, modify it, reload it, and so on. The state also provides an abstraction of the workload being run.
* Virtualization can enable existing operating systems to run on shared memory multiprocessors.
* Virtual machines can be used to create arbitrary test scenarios, and can lead to some very imaginative, effective quality assurance.
* Virtualization can be used to retrofit new features in existing operating systems without "too much" work.
* Virtualization can make tasks such as system migration, backup, and recovery easier and more manageable.
* Virtualization can be an effective means of providing binary compatibility.
* Virtualization on commodity hardware has been popular in co-located hosting. Many of the above benefits make such hosting secure, cost-effective, and appealing in general.
* Virtualization is fun.
* Plenty of other reasons ...
Variations
Generically speaking, in order to virtualize, you would use a layer of software that provides the illusion of a "real" machine to multiple instances of "virtual machines". This layer is traditionally called the Virtual Machine Monitor (VMM).
There are many (often intertwined) high-level ways to think about a virtualization system's architecture. Consider some scenarios:
A VMM could itself run directly on the real hardware - without requiring a "host" operating system. In this case, the VMM is the (minimal) OS.
A VMM could be hosted, and would run entirely as an application on top of a host operating system. It would use the host OS API to do everything. Furthermore, depending on whether the host and the virtual machine's architectures are identical or not, instruction set emulation may be involved.
From the point of view of how (and where) instructions get executed: you can handle all instructions that execute on a virtual machine in software; you can execute most of the instructions (maybe even some privileged instructions) directly on the real processor, with certain instructions handled in software; you can handle all privileged instructions in software ...
A different approach, with rather different goals, is that of complete machine simulation. SimOS and Simics, as discussed later, are examples of this approach.
Although architectures have been designed explicitly with virtualizationWhy Virtualization in mind, a typical hardware platform, and a typical operating system, both are not very conducive to virtualization.
As mentioned above, many architectures have privileged and non-privileged instructions. Assuming the programs you want to run on the various virtual machines on a system are all native to the architecture (in other words, it would not necessitate emulation of the instruction set). Thus, the virtual machine can be run in non-privileged mode. One would imagine that non-privileged instructions can be directly executed (without involving the VMM), and since the privileged instructions would cause a trap (since they are being executed in non-privileged mode), they can be "caught" by the VMM, and appropriate action can be taken (they can be simulated by the VMM in software, say). Problems arise from the fact that there may be instructions that are non-privileged, but their behavior depends on the processor mode - these instructions are sensitive, but they do not cause traps.
Cheers, frizzy.
Following are some (possibly overlapping) representative reasons for and benefits of virtualization.
* Virtual machines can be used to consolidate the workloads of several under-utilized servers to fewer machines, perhaps a single machine (server consolidation). Related benefits (perceived or real, but often cited by vendors) are savings on hardware, environmental costs, management, and administration of the server infrastructure.
* The need to run legacy applications is served well by virtual machines. A legacy application might simply not run on newer hardware and/or operating systems. Even if it does, if may under-utilize the server, so as above, it makes sense to consolidate several applications. This may be difficult without virtualization as such applications are usually not written to co-exist within a single execution environment (consider applications with hard-coded System V IPC keys, as a trivial example).
* Virtual machines can be used to provide secure, isolated sandboxes for running untrusted applications. You could even create such an execution environment dynamically - on the fly - as you download something from the Internet and run it. You can think of creative schemes, such as those involving address obfuscation. Virtualization is an important concept in building secure computing platforms.
* Virtual machines can be used to create operating systems, or execution environments with resource limits, and given the right schedulers, resource guarantees. Partitioning usually goes hand-in-hand with quality of service in the creation of QoS-enabled operating systems.
* Virtual machines can provide the illusion of hardware, or hardware configuration that you do not have (such as SCSI devices, multiple processors, ...) Virtualization can also be used to simulate networks of independent computers.
* Virtual machines can be used to run multiple operating systems simultaneously: different versions, or even entirely different systems, which can be on hot standby. Some such systems may be hard or impossible to run on newer real hardware.
* Virtual machines allow for powerful debugging and performance monitoring. You can put such tools in the virtual machine monitor, for example. Operating systems can be debugged without losing productivity, or setting up more complicated debugging scenarios.
* Virtual machines can isolate what they run, so they provide fault and error containment. You can inject faults proactively into software to study its subsequent behavior.
* Virtual machines make software easier to migrate, thus aiding application and system mobility.
* You can treat application suites as appliances by "packaging" and running each in a virtual machine.
* Virtual machines are great tools for research and academic experiments. Since they provide isolation, they are safer to work with. They encapsulate the entire state of a running system: you can save the state, examine it, modify it, reload it, and so on. The state also provides an abstraction of the workload being run.
* Virtualization can enable existing operating systems to run on shared memory multiprocessors.
* Virtual machines can be used to create arbitrary test scenarios, and can lead to some very imaginative, effective quality assurance.
* Virtualization can be used to retrofit new features in existing operating systems without "too much" work.
* Virtualization can make tasks such as system migration, backup, and recovery easier and more manageable.
* Virtualization can be an effective means of providing binary compatibility.
* Virtualization on commodity hardware has been popular in co-located hosting. Many of the above benefits make such hosting secure, cost-effective, and appealing in general.
* Virtualization is fun.
* Plenty of other reasons ...
Variations
Generically speaking, in order to virtualize, you would use a layer of software that provides the illusion of a "real" machine to multiple instances of "virtual machines". This layer is traditionally called the Virtual Machine Monitor (VMM).
There are many (often intertwined) high-level ways to think about a virtualization system's architecture. Consider some scenarios:
A VMM could itself run directly on the real hardware - without requiring a "host" operating system. In this case, the VMM is the (minimal) OS.
A VMM could be hosted, and would run entirely as an application on top of a host operating system. It would use the host OS API to do everything. Furthermore, depending on whether the host and the virtual machine's architectures are identical or not, instruction set emulation may be involved.
From the point of view of how (and where) instructions get executed: you can handle all instructions that execute on a virtual machine in software; you can execute most of the instructions (maybe even some privileged instructions) directly on the real processor, with certain instructions handled in software; you can handle all privileged instructions in software ...
A different approach, with rather different goals, is that of complete machine simulation. SimOS and Simics, as discussed later, are examples of this approach.
Although architectures have been designed explicitly with virtualizationWhy Virtualization in mind, a typical hardware platform, and a typical operating system, both are not very conducive to virtualization.
As mentioned above, many architectures have privileged and non-privileged instructions. Assuming the programs you want to run on the various virtual machines on a system are all native to the architecture (in other words, it would not necessitate emulation of the instruction set). Thus, the virtual machine can be run in non-privileged mode. One would imagine that non-privileged instructions can be directly executed (without involving the VMM), and since the privileged instructions would cause a trap (since they are being executed in non-privileged mode), they can be "caught" by the VMM, and appropriate action can be taken (they can be simulated by the VMM in software, say). Problems arise from the fact that there may be instructions that are non-privileged, but their behavior depends on the processor mode - these instructions are sensitive, but they do not cause traps.
Cheers, frizzy.
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