Archives d’Auteur: Owner

Software Vs Hardware RAID

A redundant array of independent disks (RAID) allows high levels of storage reliability. RAID is not a backup solution. It is used to improve disk I/O (performance) and reliability of your server or workstation. A RAID can be deployed using both software and hardware.
Below is a quick comparison of hardware vs software RAID.

Feature Software RAID Hardware RAID
Cost:
Software RAID is part of OS, so no need to spend extract money.		 Low High
Complexity:
The software RAID works on partition level and it can sometime increase complexity if you mix different partitions and hardware RAID.		 Medium to high Low
Write back caching (BBU):
The software RAID cannot add a battery. Hardware RAID can run in write-back mode if it has a BBU installed. With BBU pending writes are not lost on a power failure.		 No Yes
Performance:
With the software based RAID0 and RAID1 performance is negligible. However, performance goes down when you use parity-based arrays and/or several arrays at the same time. The performance of a software-based array is dependent on the server CPU performance and current load.		 Depend upon usage High
Overheads (CPU, RAM etc): 
The software RAID must use server’s CPU and RAM for RAID software. The more hard drives means more CPU cycle will go to software RAID instead of your Apache / Postfix or MySQL server.		 Depend upon usage No
Disk hot swapping:
It means replacing hard disk without shutting down the server. Many RAID controller supports disk hot swapping.		 No Yes
Hot spare support:
A hard disk is physically installed in the array which stays inactive until an active drive fails, when the system automatically replaces the failed drive with the spare, rebuilding the array with the spare hard disk included.		 Yes Yes
/boot partition:
It is hard to make fail over with software RAID if /boot fails while booting the server. This can result into unexpected errors and data loss. However, LILO and FreeBSD loader can get around this problem too.		 No Yes
Open source factor:
*BSD / OpenSolaris and Linux RAID software drivers are open source. It means more people can fix problems as compare to a closed source hardware firmware. You can move, mix and match different sizes with open source software RAID.		 Yes No
Vendor lock in (open formats): See above. No Yes
Higher write throughput:
Hardware RAID with BBU may offers higher write throughput.		 No Yes
Faster rebuilds:
Hardware RAID with BBU may offers faster rebuilds as compare to software based solution.		 No Yes
Can act as a backup solution?:
Both software and hardware RAID cannot protect you against human errors or system failures or viruses. Daily scheduled and off site backups of your system are highly recommended. Use tools such as rsync, rsnapshot, tar, dump, restore and others to make daily backups.		 No No
Recommend usage: +Low cost solution
+Better for RAID0 or RAID1
+Single server / workstation
+Perfect for home and small business users.
+No vendor lock-ins		 +Do you run a mission critical cluster or setup?
+Heavy database driven dynamic site
+Do you want the highest performance possible?

iSCSI

iSCSI is Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities, developed by the Internet Engineering Task Force (IETF). By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. The iSCSI protocol is among the key technologies expected to help bring about rapid development of the storage area network (SAN) market, by increasing the capabilities and performance of storage data transmission. Because of the ubiquity of IP networks, iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval.

In essence, iSCSI allows two hosts to negotiate and then exchange SCSI commands using internet protocol (IP) networks. By doing this, iSCSI takes a popular high-performance local storage bus and emulates it over a wide range of networks, creating a storage area network (SAN). Unlike some SAN protocols, iSCSI requires no dedicated cabling; it can be run over existing IP infrastructure. As a result, iSCSI is often seen as a low-cost alternative to fiber channel, which requires dedicated infrastructure except in its FCoE (Fibre Channel over Ethernet) form. However, the performance of an iSCSI SAN deployment can be severely degraded if not operated on a dedicated network or subnet (LAN or VLAN), due to competition for a fixed amount of bandwidth.

Although iSCSI can communicate with arbitrary types of SCSI devices, system administrators almost always use it to allow server computers (such as database servers) to access disk volumes on storage arrays.

 

CDN (Content Delivery Network)

A content delivery network or content distribution network (CDN) is a large distributed system of servers deployed in multiple data centers across the internet. The goal of a CDN is to serve content to end-users with high availability and high performance. CDNs serve a large fraction of the Internet content today, including web objects (text, graphics and scripts), downloadable objects (media files, software, documents), applications (e-commerce, portals), streaming media, on-demand streaming media, and social networks.

The use of CDN technology has obvious economic advantages to enterprises who expect, or experience, large numbers of hits on their Web sites from locations all over the world. If dozens or hundreds of other users happen to select the same Web page or content simultaneously, the CDN sends the content to each of them without delay or time-out. Problems with excessive latency, as well as large variations in latency from moment to moment (which can cause annoying « jitter » in streaming audio and video), are minimized. The bandwith each user « sees » is maximized. The difference is noticed most by users with high-speed Internet connections who often demand streaming content or large files.

Another advantage of CDN technology is content redundancy that provides a fail-safe feature and allows for graceful degradation in the event of damage to, or malfunction of, a part of the Internet. Even during a large-scale attack that disables many servers, content on a CDN will remain available to at least some users. Still another advantage of CDN technology is the fact that it inherently offers enhanced data backup, archiving, and storage capacity. This can benefit individuals and enterprises who rely on online data backup services.

What is a Cluster?

Microsoft Cluster Server (MSCS) is computer program that allows servers to work together as a computer cluster, to provide failover and increased availability of applications.

Microsoft has three technologies for clustering: Microsoft Cluster Service (MSCS), Component Load Balancing (CLB) , and Network Load Balancing Services (NLB). In windows Server 2008  the MSCS service has been renamed to Windows Server Failover Clustering and the Component Load Balancing (CLB) feature has been deprecated.

cluster

What is Circular Logging?

Circular logging is a method of conserving hard disk space in the Microsoft Exchange Transactional Logging process. It works by overwriting individual log files to keep the transactional log (the set of all log files) from expanding without limit on the hard disk.

When circular logging is disabled, every single log file goes into the transactional log database, and no limit exists as to how large that database can get. When circular logging is enabled, however, the transactional log can only grow to one megabyte (1 MB) in size. After that limit has been reached, the first log file is overwritten automatically to keep the transactional log database from growing any larger. The term « circular » arises from the fact that the set of log files starts to « rotate » once the disk space limit is reached, something like a LIFO (last-in, first-out) queue.

Circular logging is commonly used with Exchange native data protection, because in that mode, backups are not made so a detailed transactional log is not necessary. Circular logging is disabled by default in Exchange 2010. That’s because, if circular logging has been enabled and the database becomes corrupted or otherwise compromised, it cannot be completely recovered if data has been added more recently than the time that the last full backup was created.

CryptoLocker Ransomware Infections

CryptoLocker is a new variant of ransomware that restricts access to infected computers and demands the victim provide a payment to the attackers in order to decrypt and recover their files. As of this time, the primary means of infection appears to be phishing emails containing malicious attachments.

CryptoLocker appears to have been spreading through fake emails designed to mimic the look of legitimate businesses and through phony FedEx and UPS tracking notices.  In addition, there have been reports that some victims saw the malware appear following after a previous infection from one of several botnets frequently leveraged in the cyber-criminal underground.

The malware has the ability to find and encrypt files located within shared network drives, USB drives, external hard drives, network file shares and even some cloud storage drives.  If one computer on a network becomes infected, mapped network drives could also become infected. CryptoLocker then connects to the attackers’ command and control (C2) server to deposit the asymmetric private encryption key out of the victim’s reach.

The following preventative measures to protect their computer networks from a CryptoLocker infection:

  • Conduct routine backups of important files, keeping the backups stored offline.
  • Maintain up-to-date anti-virus software.
  • Keep your operating system and software up-to-date with the latest patches.
  • Do not follow unsolicited web links in email.
  • Use caution when opening email attachments.
  • Follow safe practices when browsing the web.

Windows Storage Server

Windows Storage Server is a version of Windows Server that’s licensed to OEMs for use in network-attached storage appliances. Windows Storage Server 2008 included a couple of features — namely single instance storage (file deduplication) and the Microsoft iSCSI Software Target — that differentiated it from other editions of Windows Server 2008. But there are no such distinguishing characteristics of Windows Storage Server 2012, which has no storage features beyond those found in every other edition of Windows Server 2012. Windows Storage Server 2012 is Windows Storage Server only because it is sold exclusively through Microsoft’s hardware partners with storage systems such as the HP StoreEasy 5530.

Windows Storage Server 2012 is available in Workgroup and Standard editions. The Workgroup license is limited to a single CPU socket, 32GB of RAM, six isks, and 250 concurrent SMB connections. The Standard license supports 64 CPU sockets and 2TB of RAM, and it has no restrictions on the number of disk drives or concurrent SMB connections. Standard also has a number of features — notably fail-over clustering, data deduplication, and the ability to host Hyper-V virtual machines — that you don’t get in the Workgroup edition.

WPA vs WPA2 for Wireless Security

As the name suggests, WPA2 is a second, newer version of Wireless Protected Access (WPA) security and access control technology for Wi-Fi wireless networking. WPA2 is available on all certified Wi-Fi hardware since 2006 and was an optional feature on some products before that. It is designed to improve the security of Wi-Fi connections by requiring use of stronger wireless encryption than what WPA requires. Specifically, WPA2 does not allow use of an algorithm called TKIP (Temporal Key Integrity Protocol) that has known security holes (limitations).

Most wireless routers for home networks support both WPA and WPA2 and administrators must choose which one to run. Obviously, WPA2 is the simpler, safer choice. Some techies point out that using WPA2 requires Wi-Fi hardware to work harder in running the more advanced encryption algorithms, which can theoretically slow down the network’s overall performance compared to running WPA. Network owners can make their own choice but should run experiments to decide whether they notice any difference in their networks speeds with WPA2 vs. WPA.

Parallels Desktop for Mac

With Parallels Desktop for Mac, you can seamlessly run both Windows and Mac OS X applications side-by-side without rebooting. MacBook_Air_13in_PD8_cmyk
Drag and drop files between Windows and Mac applications and launch Windows applications from your Mac dock.

Powerful performance lets you run Windows productivity applications, even graphics intensive ones, with ease.

With Parallels Desktop, you can:

• Open Windows programs side-by-side with your Mac OS X applications, without having to restart
• Copy and paste text and drag and drop objects between Mac and Windows applications
• Run Windows games and other 3D programs
• Transfer all your data from a PC and use it on your Mac
• Easily share files, devices, and other resources between Windows and the Mac
• Install other operating systems, such as Linux, Google Chrome OS, another copy of OS X Mountain Lion, and Mac OS X Server, and use them together

Windows 8.1 for Business

Someone’s business device should be just as customized, responsive, and easy to use as their own personal device. Each person in your organization has unique needs. Some need a highly mobile, always connected device. Others need the high performance of a notebook packed with features. Windows 8.1 provides flexibility and choice across a range of options–touch, type, or voice input–individuals can choose the device that best fits their needs.

Workers can customize their Windows 8.1 Preview device to suit their individual needs and work styles. Multiple windows and multimonitor enhancements allow workers to arrange their apps, sites, customize their Start screen, and change their desktop just the way they need to. IT professionals can allow workers to customize their Start screen with relevant apps and live tiles or they can choose to manage the Start screen experience through Group Policy either for individuals or for groups.

With new desktop enhancements, including the new Start button, workers can easily transition between the Start screen and the desktop. IT professionals can also customize the Start button to open the Apps view, which provides a complete list of installed apps. This list can be reordered by category, date, or name, and desktop apps can appear at the front of the list. Windows 8.1 can also boot right to the desktop. In fact, you can start directly in any view– the Start screen, Apps view, the desktop, or even a single app. Make important apps easily accessible in the Start screen on company-issued devices. This includes the ability to manage different Start screen configurations for different groups and roles by using Group Policy.

With assigned access, you can enable a single Windows Store app experience on dedicateduse devices. You might want to run a customer service app in a retail store device, or have a single learning app running in school. Enabling assigned access turns on a predefined set of  filters that blocks other actions so the specified app runs and system files and other apps can’t be accessed. Windows 8.1 makes managing personal devices much easier for Bring Your Own Devices

(BYOD) programs. New features make it possible to more securely allow access to corporate resources–like work folders, apps, and services–from any Internet connection. The management,security, monitoring, and compliance benefits of Windows Server,
Active Directory, Group Policy, Domain Join, System Center, Windows Intune, and MDOP, can continue to support devices running Windows 8.1. You can also benefit from the high levels of hardware and software compatibility with Windows 8.1. The majority of Windows
desktop apps and Windows Store apps will run on Windows 8.1.

Windows 8.1 Preview delivers enterprise-grade security through enhanced access control, improved data protection, and new features that make devices less susceptible to malware threats. Windows 8.1 Preview and Windows Server together introduce many features that make  it easier for you to embrace BYOD programs, keeping your people productive on their own mobile devices, while company information is protected. Windows 8.1 gives you more options to manage user-owned and controlled devices. New Open Mobile Alliance Device Management (OMA-DM) capabilities are built in and enable mobile device management using third-party MDM solutions with no additional agent required. Enhanced policies allow you to manage more settings from both Windows Intune and the third-party MDM solutions for both Windows 8.1 and Windows RT 8.1 devices.

Windows 8.1 personal devices include an option to join the workplace, allowing workers to access network resources, such as a SharePoint site from their personal devices. They can also choose to enroll in the device management service, to gain access to access
to the company portal, get corporate apps, and manage their own device. With work folders, they can access their work files across all their devices, with automatic synchronization to your file servers in your data center and back out to their other devices. IT professionals can enforce dynamic access control policies on the Work Folder Sync Share (including automated rights management.) When workers remove their device from the corporate network, the corporate data can no longer be accessed.