Month: April 2017

Tech Terms: Facetime

FaceTime is a video telephone / video chat service somewhat similar to Skype and Google Hangouts that makes it possible to conduct one-on-one video calls between newer Apple iPhone, iPad, iPod touch and Mac notebooks and desktops.

FaceTime App Requires AppleID
Apple’s FaceTime service is free to use but does require an Apple ID and a Wi-Fi connection, although future versions of FaceTime may also work over 3G and/or 4G connections, and several apps are currently available that make FaceTime over a 3G connection possible on a jailbroken iPhone.
FaceTime first debuted in the second half of 2010 on the iPhone 4, and currently supports the iPhone 4 and later, iPad 2 and later, the fourth generation iPod touch and later, and Macs with Mac OS X Snow Leopard (v10.6.6) and later installed. Some FaceTime features, like 720p resolution, are only available on certain platforms such as newer MacBook Pros and iMacs.

How to Set Up FaceTime on Your Apple Device

  • From settings tap “FaceTime”
  • Turn on FaceTime and tap “Use Your Apple ID”
  • Enter your Apple ID and password then tap to sign in
  • Verify the log in details then tap “Next”
  • Choose an email address and phone number for incoming and outgoing FaceTime calls

FaceTime Compatibility for Android Devices

FaceTime is incompatible with non-Apple devices as it is a proprietary app and service. For non-Apple users, there exists a number of alternative Android apps including Google Hangouts, ooVoo and Skype.


Tips & Tricks: macOS Universal Clipboard

Ensure you are signed into the same iCloud account, connected to the same network and to be within Bluetooth range (Universal Clipboard doesn’t work over the internet for security reasons).

In Sierra, navigate to System Preferences > General and select the Allow Handoff between this Mac and your iCloud devices. 

On an iOS device, go to Settings > General > Handoff & Suggested Apps, then tap to turn on Handoff.

Tech Terms: Directory

A directory is defined as an organizational unit, or container, used to organize folders and files into a hierarchical structure.
A directory contains bookkeeping information about files that are, figuratively speaking, beneath them in the hierarchy. You can think of a directory as a file cabinet that contains folders that contain files directory

File Paths and the Root Directory

Computer manuals often describe directories and file structures in terms of an inverted tree. The files and directories at any level are contained in the directory above them. To access a file, you may need to specify the names of all the directories above it. You do this by specifying a path.

The topmost directory in any file is called the root directory. A directory that is below another directory is called a subdirectory. A directory above a subdirectory is called the parent directory. Under DOS and Windows, the root directory is a back slash (\).

To read information from, or write information into, a directory, you must use an operating system command. You cannot directly edit directory files. For example, the DIR command in DOS reads a directory file and displays its contents.

GUI Folder

Many graphical user interfaces use the term folder instead of directory. For example, Windows Explorer will display the hierarchical structure of files, folders, and drives on your computer in addition to showing any mapped network drives. The Windows Explorer GUI makes it easy to see the folder hierarchy and serves as a primary tool to copy, move, rename or search for files and folders on your computer.

Other Meanings of the Word Directory
In networks, a database of network resources, such as email addresses. See under directory service.


Tech Terms: DAS

DAS is short for direct attached storage.
Direct attached storage (DAS), also called direct attach storage, is digital storage that is attached directly to a computer or a server. In other words, DAS isn’t part of a storage network. The most familiar example of DAS is the internal hard drive in a laptop or desktop PC. In practice, the phrase direct attached storage is used most often in reference to dedicated storage arrays attached directly to servers. It is used to distinguish DAS from networked storage arrangements, like SAN or NAS devices.

DAS Devices Explained
DAS can refer to a single drive or a group of drives that are connected together, as in a RAID array. In addition, DAS devices can be housed inside a PC or server (as is the case with internal hard drives) or outside the PC or server (as is the case with external hard drives and storage appliances). Multiple systems can use the same DAS device, as long as each PC or server has a separate connection to the storage device.

The primary benefits of DAS include simplicity and low cost. Installing networked storage systems, like NAS and SAN devices, requires more planning, as well as the purchase and deployment of network hardware, such as routers and switches, in addition to appropriate cabling and connections. By contrast, most PCs and many servers come with DAS already installed, and if you want to add more direct attached storage, generally all you need to purchase is a storage device and possibly a cable. Maintaining DAS is also very simple; by contrast, SAN and NAS solutions usually require management software and may require monitoring software as well.

The Difference Between DAS, SAN and NAS
In the early days of computing, DAS was the only type of storage available. In fact, the term direct attached storage didn’t come into use until much later when people needed a way to differentiate between traditional storage and SAN and NAS devices.

NAS (network attached storage) offers file-level storage for end users that are connected to a network. The advantage of NAS over DAS is that it simplifies file sharing among multiple users while potentially offering faster performance than a traditional file server.

SAN (storage area network) refers to a network of storage devices that provides block-level storage for servers in a data center. For large organizations with many servers, SAN offers better performance and flexibility than DAS, along with potential cost savings, although SAN hardware can be costly.

Many SAN and NAS devices can also be used as DAS devices. The difference lies in whether they are attached directly to a server or attached to a network via routers and switches.

Direct Attached Storage Implementation
Setting up a DAS device is generally very simple. When you purchase a PC, DAS is included in the form of the hard drive. If you would like to add more direct attached storage to a laptop or desktop, you can attach a plug-and-play external hard drive.
DAS is also included in many servers. Connecting additional DAS devices to servers is a little more complicated than adding DAS to a PC, but it is generally simpler than connecting SAN or NAS devices because it doesn’t require you to design a network or purchase hardware like routers and switches. Depending on the type of server, you may be able to add DAS in the form of additional drives in your existing server chassis. Other times, DAS sits in a separate chassis. You can also purchase DAS as storage appliances that you can connect directly to your servers. DAS deployment may require some configuration, but most IT workers can handle it on their own without outside consultants or specialized technical experts.

Using DAS is very easy. You simply save files as usual. Your operating system will allow you to view, rename, delete and perform other operations on the files on your DAS.

DAS Technology
DAS devices can utilize traditional spinning hard disk drives or solid state media. Hard disk drives (HDDs) are less expensive than solid state drives (SDDs) on a per gigabyte basis. However, they aren’t as fast as SDDs. The majority of DAS devices sold today use hard disk drives, although SSDs and hybrid devices are becoming more popular, particularly for applications where performance is paramount, such as Big Data analytics.

Conversely, SSDs offer the fastest performance, but they are also the most expensive. However, in recent years, they have become more affordable. In addition, because SSDs don’t have a spinning disk, they last longer and offer better reliability than HDDs. Many vendors now offer SSDs as an option on mid- to high-end servers for part or all of the storage capacity.
DAS devices can connect to PCs and servers via a variety of protocols, including SCSI, SAS, SATA, ATA, eSATA and Fibre Channel.


Tips & Tricks: Record Screen with xBox App

The new built-in Windows 10 Xbox app also includes a screen recording feature that lets you record the screen of the active window, as well. To use it, start the Xbox app, click Win+G to open the Game bar and select Screenshot or Start Recording.

Tech Terms: RAID

RAID is short for redundant array of independent disks.

Originally, the term RAID was defined as redundant array of inexpensive disks, but now it usually refers to a redundant array of independent disks. RAID storage uses multiple disks in order to provide fault tolerance, to improve overall performance, and to increase storage capacity in a system. This is in contrast with older storage devices that used only a single disk drive to store data.

RAID allows you to store the same data redundantly (in multiple paces) in a balanced way to improve overall performance. RAID disk drives are used frequently on servers but aren’t generally necessary for personal computers.

How RAID Works
With RAID technology, data can be mirrored on one or more disks in the same array, so that if one disk fails, the data is preserved. Thanks to a technique known as striping (a technique for spreading data over multiple disk drives), RAID also offers the option of reading or writing to more than one disk at the same time in order to improve performance.

In this arrangement, sequential data is broken into segments which are sent to the various disks in the array, speeding up throughput. A typical RAID array uses multiple disks that appear to be a single device so it can provide more storage capacity than a single disk.

Standard RAID Levels
RAID devices use many different architectures, called levels, depending on the desired balance between performance and fault tolerance. RAID levels describe how data is distributed across the drives. Standard RAID levels include the following:

  • Level 0: Striped disk array without fault tolerance. Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails then all data in the array is lost.
  • Level 1: Mirroring and duplexing. Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks.
  • Level 2: Error-correcting coding. Not a typical implementation and rarely used, Level 2 stripes data at the bit level rather than the block level.
  • Level 3: Bit-interleaved parity. Provides byte-level striping with a dedicated parity disk. Level 3, which cannot service simultaneous multiple requests, also is rarely used.
  • Level 4: Dedicated parity drive. A commonly used implementation of RAID, Level 4 provides block-level striping (like Level 0) with a parity disk. If a data disk fails, the parity data is used to create a replacement disk. A disadvantage to Level 4 is that the parity disk can create write bottlenecks.
  • Level 5: Block interleaved distributed parity. Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance. Level 5 is one of the most popular implementations of RAID.
  • Level 6: Independent data disks with double parity. Provides block-level striping with parity data distributed across all disks.
  • Level 10: A stripe of mirrors. Not one of the original RAID levels, multiple RAID 1 mirrors are created, and a RAID 0 stripe is created over these.

Non-Standard RAID Levels
Some devices use more than one level in a hybrid or nested arrangement, and some vendors also offer non-standard proprietary RAID levels. Examples of non-standard RAID levels include the following:

  • Level 0+1: A Mirror of Stripes. Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.
  • Level 7: A trademark of Storage Computer Corporation that adds caching to Levels 3 or 4.
  • RAID 1E: A RAID 1 implementation with more than two disks. Data striping is combined with mirroring each written stripe to one of the remaining disks in the array.
  • RAID S: Also called Parity RAID, this is EMC Corporation’s proprietary striped parity RAID system used in its Symmetrix storage systems.
  • RAID History and Alternative Storage Options. Before RAID devices became popular, most systems used a single drive to store data. This arrangement is sometimes referred to as a SLED (single large expensive disk). However, SLEDs have some drawbacks. First, they can create I/O bottlenecks because the data cannot be read from the disk quickly enough to keep up with the other components in a system, particularly the processor. Second, if a SLED fails, all the data is lost unless it has been recently backed up onto another disk or tape.

In 1987, three University of California, Berkeley, researchers — David Patterson, Garth A. Gibson, and Randy Katz — first defined the term RAID in a paper titled A Case for Redundant Arrays of Inexpensive Disks (RAID). They theorized that spreading data across multiple drives could improve system performance, lower costs and reduce power consumption while avoiding the potential reliability problems inherent in using inexpensive, and less reliable, disks. The paper also described the five original RAID levels.

Today, RAID technology is nearly ubiquitous among enterprise storage devices and is also found in many high-capacity consumer storage devices. However, some non-RAID storage options do exist. One alternative is JBOD (Just a Bunch of Drives). JBOD architecture utilizes multiple disks, but each disk in the device is addressed separately. JBOD provides increased storage capacity versus a single disk, but doesn’t offer the same fault tolerance and performance benefits as RAID devices.

Another RAID alternative is concatenation or spanning. This is the practice of combining multiple disk drives so that they appear to be a single drive. Spanning increases the storage capacity of a drive; however, as with JBOD, spanning does not provide reliability or speed benefits.

RAID Is Not Data Backup
RAID should not be confused with data backup. Although some RAID levels do provide redundancy, experts advise utilizing a separate storage system for backup and disaster recovery purposes.

Setting Up a RAID Array
In order to set up a RAID array, you’ll need a group of disk drives and either a software or a hardware controller. Software RAID runs directly on a server, utilizing server resources. As a result, it may cause some applications to run more slowly. Most server operating systems include some built-in RAID management capabilities.
You can also set up your own RAID array by adding a RAID controller to a server or a desktop PC. The RAID controller runs essentially the same software, but it uses its own processor instead of the system’s CPU. Some less expensive “fake RAID” controllers provide RAID management software but don’t have a separate processor.

Alternatively, you can purchase a pre-built RAID array from a storage vendor. These appliances generally include two RAID controllers and a group of disks in their own housing.

Using a RAID array is usually no different than using any other kind of primary storage. The RAID management will be handled by the hardware or software controller and is generally invisible to the end user.

RAID Technology Standards
The Storage Networking Industry Association has established the Common RAID Disk Data Format (DDF) specification. In an effort to promote interoperability among different RAID vendors, it defines how data should be distributed across the disks in a RAID device.

Another industry group called the RAID Advisory Board worked during the 1990s to promote RAID technology, but the group is no longer active.


Tech Terms: Application

An application is any program, or group of programs, that is designed for the end user. Application software can be divided into two general classes: systems software and applications software. Applications software (also called end-user programs) include such things as database programs, word processors, Web browsers and spreadsheets.

In contrast, Systems software consists of low-level programs that interact with the computer at a very basic level. This includes operating systems, compilers, and utilities for managing computer resources.
Recommended Reading: Webopedia’s enterprise application definition.
App Versus Application
A similar phrase, app is used to describe a type of application that has a single functionality whereas an application may handle a number of functions.