When the basin is small, or it's time to choose a VPS server
Recommendations for analyzing performance and choosing the right VDS hosting . It is meant to be read by those users who need to make a decision on the expediency of transferring web projects with a heavy load to a web server (forum, media portal, online store) from hosting to a virtual dedicated server.
1. When an Internet project has outgrown shared hosting
1.1. What is VDS
Virtual dedicated server - VDS (or VPS virtual private server) is a mini-server created with the help of special programs and technologies, limited in resources, but much more powerful than web hosting, completely separate and controlled by its owner.
1.2. Signs of increased hosting load
In the process of developing an Internet project comes one of three possible situations:
- When the site starts to open longer than 4 seconds, it becomes unavailable every day, and angry letters about overloading the processor and web server memory come from hosting technical support. As a rule, this happens because of the increase in the size of the MySQL database used in most modern CMS # and because of the increase in the number of visitors to the website. As a result of the development of any forum, blog or social network, new members appear, more and more messages, comments appear. People are visiting the site more often. Because of this, the load on the server processor due to database queries becomes so high that it already violates the rules of hosting. For example: HostGator, in its rules , clause 7a, prohibits MySQL from working for more than 15 seconds or using more than 25% of system resources for more than 90 seconds.
- When further developing an Internet project, it is necessary to use scripts or web server modules that require customization of the server operating system and therefore cannot work on shared hosting. For example, a mail server (Sendmail , Postfix or Exim ), an FTP server or a Nginx web server.
- When it is necessary to solve some security issues, for example, make it impossible to access third-party files or refuse FTP and replace it with #SFTP.
At this stage, the site owner is thinking about transferring their projects to VDS hosting. VDS hosting is often viewed as a compromise in a situation where the power and functionality of a shared hosting for $ 3 - $ 7 a month is not enough, and a dedicated server priced at $ 150 to $ 300 is still too expensive. VDS (Virtual Dedicated Server) virtual dedicated server is a software emulation service for a real physical server. VPS (Virtual Private Server) is a virtual private server, meaning in the same sense as VDS, but with the difference that in practice it is applied only to virtual servers based on the OpenVZ / Virtuozzo technology, which provides virtualization at the kernel level of the OS and is less reliable than other technologies (XEN, KVM, etc.).
2. Comparison of shared-hosting and VDS
One of the most common misconceptions about using VDS is that any site will always run faster on a virtual server than on a regular web hosting service. In fact, VDS is at least a dedicated server, but a virtual, and therefore MySQL database server, mail server, all services will be run on it within its limited resources (there are exceptions in the form of some managed VDS).
Unlike web hosting, where all clients access a shared database server, very often hosted on a separate physical server and running on a powerful hardware platform. Also, on VDS, depending on the virtualization technology, there may be performance problems with the hard disk during high intensity file operations (a frequent problem with VPS based on OpenVZ / Virtuozzo).
The main advantage of VDS over web hosting is a much larger amount of guaranteed RAM and processor resources for executing user scripts exclusively for any required time and the ability to self-tune the server to fit your needs. Unlike web hosting on a virtual server, you can install any applications, for example, PHP accelerator , Nginx , change PHP version (PHP 4.4.9 to 5.2.1, return from PHP 5 to PHP 4). Also, the owner of the virtual server completely controls access to files.
3. Types of VDS by level of support
3.1. Unmanaged
In the case of unmanaged VDS, the hosting company is only responsible for the smooth running of the hosting and availability from the network of your virtual server. You get a VDS with an installed operating system and must independently install and configure all the necessary programs (control panel, web server, mySQL server, mail server). This option is cheaper, but it requires good knowledge of server administration from a VDS user.
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3.2. Managed
In this case, you, as the owner of VDS, can count on the help of technical support in configuring or using a virtual server. A server control panel and a set of typical software (Apache, MySQL, PHP, FTP server, mail server) will be installed and configured for you in advance. The cost of renting a VDS will be much more, but it is convenient for those users who want to browse their site, rather than delving into the settings of the virtual server.
For example, Acenet system administrators are responsible for:
- regular OS updates, patches and security updates
- round-the-clock monitoring of the virtual server
- tracking and response to system messages about disk full, scripts exceeding the limits of server resources allocated for operation
- performing backup
- installation and configuration of various programs, servers and modules for them
| Unmanaged | Managed | What is configured in the managed version | |
| Acenet | $ 19.95 | $ 79.90 |
|
Table 1. Differences in the cost of managed and unmanaged VDS
Also, the concept of managed VDS often includes the ability to place resource-intensive programs, for example, the MySQL database server on a separate physical server, which will reduce the load on the client’s virtual server.
Hosting InMotion understands managet VDS like this :
| What does hosting support do? | What the client does on his own |
|
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Table 2. Composition of free administration services managed VPS InMotion Hosing
4. Types of virtualization when used for hosting websites
When creating virtual machines, the following concepts are used:
- Host OS - an operating system installed on a physical server (host computer)
- Guest OS - operating system installed on a virtual server
4.1. OS kernel-level virtualization
In this case, the operating system creates separate containers - virtual machines. For users, these containers look like a copy of the main server with reduced resources. Programs and system processes in different containers cannot influence each other. Access to resources and their separation between virtual machines provides the main operating system. When using this technology, it is impossible to launch a guest operating system different from the host OS on the virtual machine. Examples of such systems used in the hosting industry are Virtuozzo and FreeBSD Jail.
4.2. Hypervisor-based Virtualization
This technology uses a hypervisor - a program or electronic circuit that is installed on a host computer and provides for the creation, launch and operation of several virtual machines. All virtual machines are completely isolated and independent of each other. The hypervisor uses the capabilities of virtualized virtualization and creates an environment that completely simulates the hardware of a physical server, while the guest operating system may not know what is running in a virtual environment. A guest operating system can be any of those operating systems that are supported by the hypervisor and different in different virtual machines. Examples of a hypervisor are Xen and KVM .
5. Virtual server technologies in hosting
5.1. OpenVZ (and its commercial version of Virtuozzo )
This is one of the first and most common virtualization technologies, for example, among the participants of Best 10 VPS Hosting Providers, only one company - Acenet offers VDS based on Xen technology , all others use OpenVZ / Virtuozzo. OpenVZ - open-source - development, distributed free of charge. Based on OpenVZ, Parallels developed Virtuozzo . This technology works on Linux. Virtuozzo is easy to install and configure. But it is necessary to take into account that all virtual servers use one core, therefore, individually, you cannot enable the necessary modules for a separate VPS, memory and disk space are shared, shared between all virtual servers within the allocated limit.
This means that a neighboring VPS, creating a load on the file system with a large number of disk operations, will create a problem and cause a slowdown in your and all other virtual servers. Due to the fact that one common core of the operating system is used, you cannot install another OS in virtual servers.
Also, the use of shared resources makes it possible for owners of hosting overselling. Overselling is a situation when the server administrator expects that the client in most cases does not spend all the resources that should be on the tariff. Therefore, the resources of the physical server are distributed to a larger number of virtual machines than can simultaneously run at full capacity. For example, 4GB of RAM is installed on the physical server and it is distributed over 512 MB to 10-20 virtual machines, and not to eight.
Since, in reality, most clients do not use all the resources that should be at the tariff, problems will arise only at peak load or when the application is started, which, for example, really takes up all the memory allocated by the tariff. A virtual machine can only have the same OS as it does on the server.
Figure 1. OpenVZ Control Panel
In fact, the two only advantages of a Virtuozzo-based VPS are:
- lower cost for customers compared to virtual servers based on Xen or KVM technology.
- the ability to change server settings (for example, RAM size, amount of allocated CPU time, virtual machine disk size) without rebooting.
5.2. Xen
This is a much more stable technology. Due to the fact that each virtual server runs its own kernel, the user has full control over the system and does not depend on other users and their actions on their own VDS. Due to complete isolation from each other, a different operating system can be installed in each virtual server, and the available resources (memory, disk space) correspond exactly to the value according to the tariff. Also, which is very important, any cataclysms on a single VDS will not affect the speed and stability of the work of neighbors in the server.
For example, if on a separate VDS a process takes all the memory or creates too many file operations, then only this virtual server will slow down or stop working, and the remaining VDS will continue to work normally. Using this technology, you can install operating systems such as Linux, NetBSD, FreeBSD, OpenBSD, Windows XP or 2003 Server on a virtual server.
Figure 2. VDS organization with XEN technology
The main features of Xen: support for the para-virtualization mode in addition to hardware virtualization, the ability to migrate a running virtual machine between physical machines (for example, a cloud server). In the simplest case, the system can physically work on two nodes - virtual machines are distributed between them, and their disks are duplicated and stored on both nodes.
When using Xen for the Cloud technology, if one of the nodes fails, all virtual machines are started on the second - the system remains fully functional. With the normal shutdown of one of the nodes, the machines that worked on it migrate to the second node completely unnoticed by the users of these machines. This allows you to perform sequential maintenance and updating of server hardware at any time and without interfering with users.
5.3. KVM
Virtualization technology that works at the kernel level of the operating system (which is why it is called the Kernel-based Virtual Machine) and supports hardware virtualization. For a VDS user, this means that there is almost no performance loss due to virtualization, high reliability and stability.
Figure 3. The organization of virtual machines on KVM technology
Advantages of KVM technology:
- independent and isolated allocated disk space and allocated RAM for each virtual machine.
- support for network protocols allows you to install and use VPN
- support for emulation of physical access to the console, you can control the virtual server from the moment of loading
- support any operating system on virtual servers.
5.4. Hyper-v
Microsoft's virtualization technology, running on Windows Server 2008. Hardware virtualization is used. Performance losses are minor. Permitted Guest OSs: Windows NT, 2000, 2003, 2008, XP, Vista, Linux Red Hat or Linux SUSE. Other Linux-based guest OSes are not supported.
Fig 4. Architecture of Hyper-V technology.
This technology does not have USB support for virtual machines; also, no sound is played in virtual machines. This technology is recommended if you plan to use VDS with Windows OS.
5.5. FreeBSD Jail
This is a virtualization technology that allows you to create several FreeBSD virtual machines operating in isolation on the base of a FreeBSD system installed on a physical server. The common core of the operating system is used, but the virtual machines themselves are configured completely individually. None of the processes running inside the Jailed process can affect any external processes. Other operating systems cannot be used as a guest.
5.6. VMWare
VMware ESX / ESXi Server is used for virtualization. ESX allows you to create fully isolated virtual machines, the physical resources of the server are divided into logical partitions. Currently, this virtualization platform is used for cloud hosting. For organization VDS is used very rarely.
5.7. Differences between the most popular platforms for VDS
In reality, virtual server for web hosting purposes, as a rule, are created based on the three most popular technologies: KVM, OpenVZ / Virtuozzo, Xen.
Figure 5. Voting results on the popularity of virtualization technologies from webhostingtalk.com
A comparison of the advantages and disadvantages of these technologies is given in Table 3.
| KVM | OpenVZ / Virtuozzo | Xen | |
| Own file system of any type | + | - | + |
| A dedicated area in RAM with full access and debugging capabilities | + | - | + |
| Complete isolation from neighbors | + | - | + |
| VNC-connection in the early stages of loading | + | - | limited |
| PPTP VPN | + | limited | + |
| Openvpn | + | limited | + |
| IPSec VPN | + | - | limited |
| Firewalls | + | limited | + |
| Kernel mode NFS server | + | - | - |
| Independent core | + | - | limited |
| Independent core modules | + | - | limited |
| Full control over sockets and processes | + | - | - |
| Full guest OS support (Windows, Linux, BSD, OpenSolaris, etc.) | + | - | limited |
| Emulation of PCI / PCIe cards with full access to them | + | - | limited |
| Official Linux kernel integration | + | - | + |
Table 3. Comparison of KVM, OpenVZ / Virtuozzo and Xen virtualization technologies
6. Criteria for selecting a virtual server
Usually, if you need a virtual server, this means that you will be hosting a large resource-intensive project, for example, a store ( www.dsw.com ), a news portal ( militarytimes.com ) or a social network ( www.caringbridge.org ) or a specific service. that cannot be run on a shared web hosting (for example, a mail server). Any of these options implies a greater load on the hosting of the scripts and a large attendance. When choosing a VDS hosting you need to consider several factors.
Considering the three groups, the quality of the hosting service, the cost and the level of service, we get the following criteria:
- Virtualization technology - although the most popular technology is OpenVZ / Virtuozzo and, due to historical reasons, is both a pioneer and low cost, it’s still better to choose VDS hosting based on more stable XEN, KVM or Hyper-V technologies. Of the ten leaders offering virtual servers ( http://webhostinggeeks.com/vpshosting.html ), VDS on XEN technology offers only Acenet .
- Memory size - in addition to the memory allocated for your VDS in the case of the Virtuozzo technology, there is also Burstable Memory - this is an additional memory that your scripts can use for a short time when their own resources are being used up (provided that other users did not occupy Burstable Memory at that moment).
- Disk space - the place on the disk where all your files, html pages, scripts, databases, statistics, mail will be placed.
- The size of the monthly traffic - do not forget that your traffic is consumed not only when visiting your sites, but also when uploading sites to a hosting service, installing a CMS, downloading and installing scripts and performing a backup entrenching to your local hard drive.
- The size of the CPU time used is an important indicator that determines how much of the processing power of the server processor your VDS will use. Unfortunately, this indicator is conditional and in practice it cannot be compared for different VDS hosting providers because different providers use different processors on the servers and the user does not know which ones. For example, out of the ten leaders of the http://webhostinggeeks.com/vpshosting.html rating, no hosting provider specified the characteristics of the physical servers hosting the VDS and only Acenet indicated the share of the processor, albeit in completely incomprehensible units of measurement (vCPU).
- The geographical location of the data center - the closer to the main audience of your site, the greater the likelihood that visitors will be satisfied with the speed of loading web pages. For example, when testing the download speed of a file from the InMotion Hosting data center on the east coast, the download time for users in San Francisco (1.9 seconds) and in Washington (0.36 seconds) will differ 5 times #. Ideally, it is good to be able to choose from several options, for example, InMotion Hosting has data centers on the west and east coast of the United States ( http://goo.gl/UvJVv ).
- The type of VDS operating system . It is better to choose CentOS , Debian , Ubuntu , which are distinguished by stable operation on virtual servers and a large amount of background information for those who are not well-versed in system administration. FreeBSD is a good, reliable operating system, but requires good administrative knowledge. It makes sense to choose Windows only in the case of the specific requirements of the programs (for example, when using the MSSQL database server or ASP scripts), which you will run on the VDS.
- The cost of a monthly rental VDS - please note whether the tariff includes free administration. As in this case, the hosting support administrators are interested in setting everything up right away at once.
- The cost of additional administration - you need to understand what expenses you are waiting for in those situations when you do not cope with server administration yourself. If you rent Managed VDS, then the cost of support will be included in the payment of VDS.
- The work of technical support . Schedule and schedule of technical support. Communication methods: telephone, tickets, live chat, email.
- Reviews about the hosting of real users (the work of technical support in reality, overselling, real uptime servers).
- A test period is a period of time during which you can request a refund according to the hosting rules. This is important, because only in practice the actual processor power of the server and the correspondence of the actual resources of the virtual server to those described in the tariffs will be visible.
7. Conclusion
So, placing one or more websites on a virtual dedicated server is a crucial decision that needs to be made, having considered all the pros and cons.
Advantages of using VDS:
- ability to run scripts requiring more memory and CPU time
- full user control over access to his files
- ability to customize the web server to your needs
Using VDS is:
- higher costs for hosting compared to shared-hosting
- the need to be able to administer Linux or a Windows server, or
- system administrator fees
- great user responsibility for the performance of their sites
Figure 7. Server structure with VPS.
Also, always remember that there are two factors that will not allow you to compare virtual servers of different providers for exactly all the characteristics written in the tariffs:
- One of the main indicators of virtual server power is that the share of processor time does not have a common unit of measurement, it can be measured in Mhz, it can be not specified as a percentage of processor time, in virtual processors, but in any case these units are not comparable for different hosting providers .
- Since the OpenVZ / Virtuozzo technology is often used, the hoster can and often does overselling, i.e. for example, it offers in the tariff plans of RAM for each individual VDS - and more than the sum physically is the memory on the server. This leads to the fact that during peak load on one virtual server, there is not enough resources for another. How much the hosting administration abuses the possibility of overselling, you can find out only in practice or from reviews of other users.
Therefore, choose a virtual server not only for technical specifications, but also for reviews of other users.
| Rank | Web Hosting Provider | Core specs | Features | Hosting review |
| one | Inmotion
Ultra Fast Servers | Space: 80 Gb
Bandwidth: 1000 Gb Price: $ 74.95 | Free & Easy Setup,
5 Dedicated IPs, Full cPanel / Fantastico | Inmotion Review
|
| 2 | Ultrahosting
Cheap vps solutions | Space: 40 Gb
Bandwidth: 1500 Gb Price: $ 54.00 | Free & Easy Setup,
1 Dedicated IP | UltraHosting Review
|
| 3 | NS
Secure vps hosting | Space: 50 Gb
Bandwidth: 2000 Gb Price: $ 80.00 | Free & Easy Setup,
1 Dedicated IP, Virtuozzo / Plesk 9 | NS Review
|
| four | Acenet
High Performance Servers | Space: 40 Gb
Bandwidth: 1500 Gb Price: $ 109.95 | Free & Easy Setup,
Full cPanel / Fantastico | Acenet Review
|
| five | Hostican
Affordable VPS Hosting | Space: 90 Gb
Bandwidth: Unlimited Price: $ 84.95 | cPanel / WHM / Plesk,
2 Dedicated IPs | HostICan Review
|
| 6 | Liquidweb
Reliable VPS Hosting | Space: 40 Gb
Bandwidth: 350 Gb Price: $ 100.00 | Free & Easy Setup,
4 dedicated IPs, Full cPanel / Fantastico | LiquidWeb Review
|
| 7 | Dotster
Cheap VPS Hosting | Space: 30 Gb
Bandwidth: 1000 Gb Price: $ 48.95 | Free & Easy Setup,
2 dedicated IPs, Virtuozzo / Plesk 9 | Dotster review
|
| eight | Lunarpages
Linux & Windows VPS | Space: 20 Gb
Bandwidth: 1000 Gb Price: $ 49.95 | Free & Easy Setup,
1 Dedicated IP, Virtuozzo Power Panel | Lunarpages Review
|
| 9 | 1 & 1 Internet
Cheap VPS Hosting | Space: 50 Gb
Bandwidth: 2000 Gb Price: $ 59.00 | Free SSL Certificate,
1 Dedicated IP, CentOS 5 + Plesk 9 | 1 & 1 Review
|
| ten | XL Host
Cheap VPS Hosting | Space: 10 Gb
Bandwidth: 250 Gb Price: $ 59.00 | Free & Easy Setup,
4 dedicated IPs, Tons of Extras | XL Host Review
|
Table 5. Leaders of the VDS rating - hosting from webhostingw.com
And immediately after the purchase, try to actively test your VDS at maximum load in the initial period, while it is possible to demand a refund.
Source: https://habr.com/ru/post/109451/
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