E-mail Servers

Servers designed to send, receive and make e-mail available to you..

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File Servers

Store and share files between multiple users.

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Specialty Servers

Many other ways to store/share/retrieve information.

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Generally speaking, email is taken care of by the same company who hosts your web site or provides your internet service. However, in some cases, this is done internally. However, even if an outside agency handles your e-mail for you, in some cases you would like to have an internal e-mail server also.

Internal e-mail servers have many advantages:

  1. Internal e-mail servers can provide permenant, long term storage of e-mail. Many Service Providers limit the total size of e-mail that can be on their servers at any point in time (a quota). By creating an internal e-mail server that can automatically retrieve your e-mail from an external source, you are limited only by the amount of disk space your server has.
  2. Privacy can be an issue. email flows through many paths, even if you are sending an e-mail to the person sitting next to you at the office. Sending this e-mail through your Internet Presence Provider (IPP, the people who host your e-mail) means the email goes out through your Internet Service Provider to your IPP. In many cases, email will go through several connections to make this simple trip. When you retrieve the mail it reverses the path. However, an internal email server can note that the e-mail is for internal use, and remains inside your office.
  3. Many times IPP's will limit the size of attachments for e-mail. If you have a fax server that sends recevied faxes as e-mail attachments, this can cause problems. An internal email server can relax this restriction allowing you to use these additional services.
  4. Many IPP's will limit the total size of e-mail sent during a month, though they may allow it but charge an additional fee. This can become a problem if you want to send large graphics files, faxes, or any other large attachment via e-mail. Using an internal e-mail server can save significant money in these cases.

Daily Data supports many e-mail servers, from the old "standby" Sendmail (http://www.sendmail.org/) which has been around almost as long as the Internet, to some of the latest fully integrated packages on the market now such as Zimbra (http://www.zimbra.com/) which gives a full web based calendar/contact list/e-mail program with integrated anti-virus and anti spam which rivals "normal" e-mail programs.

Email servers can, in many cases, co-exist with web or file servers.

A problem appeared shortly after Personal Computers (PC's) hit the world in the late 1970's. Multiple computers meant that information was no longer stored on one giant server any more. Important company information was being stored on individual workstations, and were shared around by carrying floppy disks from one computer to another.

With growing acceptance of the Local Area Network (LAN), the problem was solved to some degree; people could copy the files directly across the network and work on it. If they forgot to return it to its "official" workstation, however, additional problems came up as various versions of important documents were stored on different workstations. Additionally, backup became a problem, as one workstation breaking could mean the loss of important information.

A file server solves many of these problems, and is recommended any times the number of workstations exceeds two. All documents ("documents" is a term that includes spreadsheets, accounting information, and word processing files) are stored on a special computer that does nothing but stores files. Users connect to this server as if it were physically attached to their workstation, editing, saving, printing, as if it were merely an additional disk on their computer. Under normal circumstances, the slight delay in opening and changing a document is not even noticeable to the user.

The advantages, however, are enormous. First, most programs "lock" a file that is being edited on a server. This lock allows other people to view the document, but not change it (the first person to open it has the right to make changes). This simple form of "Version Control" (link to specialty page) keeps people from overwriting each others work. Additionally, all of your important information is on one computer, which you can back up as often as needed. If a workstation fails, you no longer need worry about losing the information that was on it; simply buy a new computer and connect it to your file server. Of course, if your file server fails, that is bad, but you can spend slightly more to build a machine that will be sturdy and last longer. And, with proper backups, a total failure on the server means a loss of a minimal amount of work.

Linux file servers tend to require minimal hardware. A good file server is designed for reliability, not for all the fancy extras such as good graphics, high quality sound, or speed. An older 1 Gigahertz computer with 128 Megabytes of memory is more than fast enough for a small company's file server (though you want to ensure it is reliable enough). Even with such poor specifications that it would not run a Linux workstation, Windows XP or Mac OS X without the operater getting frustrated with its sluggishness, this system could handle the requirements of a 50 user office under normal circumstances.

In many cases, a small to medium business can share use a single computer for file services and internal web services with no problems.

Database Servers

A database is an organized way to store large amounts of information for fast retrieval. If you are familiar with spreadsheets, think of a database as a spreadsheet on steroids. A database is designed to allow a specialty language, called SQL, to find information very, very fast. For example, one of the databases available to Daily Data's web hosting clients contains the distances between all zip codes in the United States. Using this database, a properly formed query can retrieve the 12 zipcodes within a 50 mile radius of 75214, searching 635,000+ entries to do so, in 0.19 seconds.

Database servers are rarely thought of on their own, except in very large installations. In most cases, database servers are "back end" parts of applications and/or web sites. In some cases, especially in medium to large businesses, however, the load on a server due to the database services required are great enough to demand one or more servers dedicated to databases only. Linux has many databases available, from MySQL, a small, extremely fast database to Oracle, the name in high end, high availability Database Servers.

Version Control Servers

Version Control servers allow many people to work on one project at the same time without fear that one person will overwrite anothers work. Think of the situation where two people, Sue and John work on the same document. Sue and John both copy the document from the file server and make changes. Sue finishes first and copies her changes back to the file server. A few minutes later, John does the same, overwriting all the work that Sue did.

Version control gives ways around this. With Version Control, Under the older version control systems, Sue would "check out" the document and, when John wanted to do the same, he would be told that Sue had it and he must wait until she was finished to check it out for editing. When Sue checked the document back in, John would get an e-mail saying it was available to edit, then he could check it out and make his changes.

In some of the newer Version Control systems, both John and Sue can check out the document simultaneously. When Sue checks it back in, only her changes have been made. Then, when John tries to check the document back in, the Version Control system attempts to merge his changes to Sue's automatically. If it can not do so, it tells John that Sue has made changes he did not know about, gives him both documents (showing what was changed by Sue) and requiring he "merge" the changes before checking the document back in.

While not for every situation, Version Control systems are a requirement for many businesses, especially where many people simultaneously work on the same project. Linux has many Version Control systems available, the most common being Subversion, which is basically a rewrite/upgrade of the Concurrent Version System (CVS) which was the standard for many years. In many cases, a Version Control system can safely share a server with other services, many times being stored on a web or file server.

File/Contact/Calendar ("cloud") Servers

When people hear "Cloud Storage" this is the main thing that comes to mind; a server which can allow files, contacts and calendars to be synchronized (stored and updated) to multiple devices, even multiple users.

Owncloud, one of the leading products of this area. With clients for Android, IOS, Microsoft Windows, Apple OSX and Linux, information can be easily shared between devices running any of these operating systems.

Two attributes of this which make it especially useful are the ability to share information with other users (or even non-users) on a very granular basis, and the ability to have your information available even if you do not have an internet connection at the time.

Virtualization

As you grow, your servers tend to multiply. You might have a web server, a file server, an e-mail server. Another server that is dedicated to your "techno-nerds" so they do not mess up everyone elses work when someone brings the server to its knees, and, in some computer intensive companies, you might have one or more "test servers".

Each time you add a server, you are increasing the chance that a piece of equipment will break. Computers are made up of many parts, and generally last a few years. Watching many different physical computers, waiting for an important one to break, and fixing it rapidly can be time consuming.

Virtualization allows many "computers" to be stored on one physical machine. The physical computer actually has a special operating system on it that allows many "virtual computers" to run, apparently simultaneously.

With virtualization, instead of several inexpensive machines that need to be watched continuously, you need only have one more powerful computer that is designed to last longer, and be easier to repair. Definitely not for everyone, but in many cases the extra expense of buying a more powerful machine, and setting it up to run virtual servers, is repaid in a very rapid way.

Daily Data specializes in Xen virtualization (developed at the University of Cambridge), and has a lot of experience in VMWare, a commercial offering that also runs under Microsoft Windows.

Note that the "virtual servers" running in this environment can be of many flavors; Daily Data currently manages "virtuals" running Microsoft, Linux and BSD Unix, all on the same physical server.

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