Highly Available Data Management in VS .NET

Making QR Code JIS X 0510 in VS .NET Highly Available Data Management
Highly Available Data Management
Scanning Quick Response Code In .NET Framework
Using Barcode Control SDK for VS .NET Control to generate, create, read, scan barcode image in .NET applications.
As SANs mature, more features will develop, and implementation costs will drop. For example, there are products that allow parallel applications to read and write from more than one server at the same time. The result is increased performance and reliability. Oracle s enhanced version of their database, called Oracle 9i RAC, is a parallelized application, and VERITAS s SANpoint Foundation Suite allows the simultaneous reading and writing of disks by the members of a SAN. There are not, however, many applications that can take advantage of this capability.
QR-Code Maker In .NET Framework
Using Barcode maker for Visual Studio .NET Control to generate, create QR image in VS .NET applications.
RAID Technology
Recognizing Quick Response Code In Visual Studio .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in VS .NET applications.
The RAID standard describes several ways to combine and manage a set of independent disks so that the resultant combination provides a level of disk redundancy. Five levels of RAID are defined, plus an additional loosely defined level that does not provide any redundancy. RAID functionality can be provided from within a disk array or on a disk controller (Hardware RAID) or from the host system (Software RAID). In general, Software RAID requires cycles from the host system s CPU; Hardware RAID is performed on a separate dedicated CPU. More on the differences between the two is discussed in the sections that follow.
Bar Code Maker In .NET Framework
Using Barcode generator for .NET framework Control to generate, create bar code image in Visual Studio .NET applications.
RAID Levels
Barcode Recognizer In Visual Studio .NET
Using Barcode recognizer for .NET framework Control to read, scan read, scan image in Visual Studio .NET applications.
The RAID Advisory Board has defined six official levels of RAID. Five of them (RAID-1 through RAID-5) provide various levels of increased disk redundancy. One more (RAID-0) does not provide any redundancy. Several other levels of RAID fall into one of two classes: combined levels and marketing-created levels. Combined levels, such as RAID 0+1 or RAID 5+0, indicate, as you might guess, a combined approach. Other levels, such as RAID-6 or RAID-S, are not recognized by the RAID Advisory Council, and generally come from one company s marketing department or another. We discuss these topics in more detail in the paragraphs that follow. As explained in the data management layers at the start of this chapter, RAID functionality is totally independent of the data stored on the disks. The data could be stored in a filesystem or in raw format (non filesystem-based); it could be user data, application data, source code, or any other sort of data. RAID simply manages where and how many times the data is written, and what, if any, calculations are performed on the data to protect it.
QR Code Creation In C#
Using Barcode creator for .NET Control to generate, create QR image in .NET applications.
RAID-0: Striping
Generating QR Code JIS X 0510 In VS .NET
Using Barcode generator for ASP.NET Control to generate, create QR Code 2d barcode image in ASP.NET applications.
RAID-0 is another name for disk striping. In a striping model, each chunk of data to be written to disk is broken up into smaller segments, with each
Making QR In VB.NET
Using Barcode drawer for .NET framework Control to generate, create Quick Response Code image in .NET applications.
7
Drawing Barcode In Visual Studio .NET
Using Barcode maker for .NET Control to generate, create barcode image in VS .NET applications.
segment written to a separate disk. Because each disk can complete the smaller writes at the same time, write performance is improved over writes to a single disk. Performance can be enhanced further by striping the writes between separate controllers too. The size of each segment is called the stripe width. In general, the optimal size of a stripe width is the average size of a disk write, divided by the number of disks in the stripe. However, if the disk array has its own cache, the rules may change. The first and most important thing to know about RAID-0 is that, unlike all the other levels of RAID, RAID-0 does not increase your system or data availability. In fact, when used by itself, RAID-0 decreases availability. In order for a stripe set to function, all of its member disks must be available. If any disk in a stripe fails, the entire stripe fails and cannot be read or written. Consider a 2GB filesystem, and disks with a 200,000-hour MTBF. If the filesystem lives on a single 2GB disk, the MTBF in is simply 200,000 hours. If the filesystem is striped across four disks, with 500MB of data on each disk, the MTBF is reduced significantly due to the increased probability that at least one of the disks will fail. Because RAID-0 adds no redundancy, it does not require any additional disk space. Please note that when we use the term RAID throughout the book as a generalized way of adding disk redundancy, we are specifically excluding RAID-0 from that discussion, since RAID-0 reduces overall system availability and all other levels increase it.
Generating Barcode In .NET Framework
Using Barcode encoder for .NET framework Control to generate, create barcode image in Visual Studio .NET applications.
Encoding Code 39 Extended In .NET Framework
Using Barcode creation for .NET framework Control to generate, create Code-39 image in Visual Studio .NET applications.
EAN 13 Encoder In .NET Framework
Using Barcode generation for ASP.NET Control to generate, create EAN13 image in ASP.NET applications.
Create Code39 In C#
Using Barcode generator for VS .NET Control to generate, create Code 39 Full ASCII image in .NET applications.
Bar Code Generation In .NET
Using Barcode generation for ASP.NET Control to generate, create bar code image in ASP.NET applications.
Paint GS1-128 In Visual Studio .NET
Using Barcode creator for ASP.NET Control to generate, create GS1-128 image in ASP.NET applications.