Understanding the Linux Reiser File System
This year, more IT professionals are going to be looking seriously at a Linux type system and trying to determine how to implement this system into existing networks. Is this on your project list for 2005? If so, this month's technical article will be an enlightening look at the choices you'll have to consider.
File System Choices
File systems provide hierarchical organisation to files, information (or meta-data) about those files, and management of space to where those files physically reside on the hard drive. Over the years, file system development has focused on performance and reliability. Recently, however, developers have started to focus on file system security and protection in an attempt to meet the growing needs of the business community.
These simple precepts have introduced highly complex file systems with some being tailored for specific applications or systems. For example, an audio/video company might require a high performance file system, whereas an accounting firm might require a file system that specialises in high security.
Administrators coming from the Microsoft server/workstation environment may be used to having the choice of FAT32 or NTFS for the installed file system. Yet in the Linux environment, administrators may be surprised at the number of file system choices Linux has to offer. What is the best file system for your environment? What will give your organisation more performance, security, or reliability?
Sometimes it is easier to just go forward with the default choice, but there are good reasons to do your homework before committing a production server to a default file system. Relevant questions include:
- How many files will this server store?
- Are the files small or large?
- Will there be requirements for specific access controls to the files?
- What are the performance expectations for the system?
These decisions are critical for the success of your system's rollout. (For more information on the various pros and cons of the major Linux file systems, click here.)
Here is an example of the some of the choices of file systems that the Linux operating system supports.
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ReiserFS Comes of Age
Journaling file systems provide integrity and prevent corruption to the indexing of your files. (For more information on Journaling file systems, http://www.linuxgazette.com/issue55/florido.html) By caching file system operations and confirming each transaction, Journaling file systems provide ACID transactions. ACID stands for:
Atomicity: In a transaction involving two or more discrete pieces of information, either all of the pieces are committed or none are.
Consistency: A transaction either creates a new and valid state of data, or, if any failure occurs, returns all data to its state before the transaction was started.
Isolation: A transaction in process and not yet committed must remain isolated from any other transaction.
Durability: Committed data is saved by the system such that, even in the event of a failure and system restart, the data is available in its correct state.
The list of Journaling file systems includes Ext3, XFS, JFS, and ReiserFS. The Reiser File System has been around for the past four years and considerable time has been invested in its development. The philosophy behind the Reiser File System (referred to as ReiserFS) is to simplify the file system's requirements into basic components. These components are used within ReiserFS to define the sorting and indexing schemes that keep track of your files. The ReiserFS development team is applying mathematical theorems to the logic of the file system. Instead of making a ‘table of contents and chapters' type of file system, ReiserFS has an operational methodology so that files can be found and presented back to the user quickly.
No doubt you have seen how quickly hard drives fill up with data. Whether on user's desktops, laptops, or servers, data collects quickly—if there's space, it will get filled. ReiserFS uses a complex ‘Balanced-Tree' environment which provides substantial performance with large amounts of files. Additionally, the ReiserFS method of storing information about the files is compact, thereby allowing the file system to handle many thousands of files efficiently and with ease.
ReiserFS has proven itself to be efficient with disk space management, fragmentation, and with performance. (For the latest performance tests on ReiserFS, http://linuxgazette.net/102/piszcz.html)
So what file system is best for you? The summation of all this is application. What are the requirements and goals of the data volume you are planning? Just choosing the default settings may get the server setup quickly and in operation, however over the coming months and years, it may be obvious that performance, redundancy, and scalability needs are not available because of default choices.
The only way you or your clients will be able to make an informed decision is to make sure that enough research has been done. Research should also involve recovery options for your systems. If there is a data disaster, Ontrack has the experience and technology to provide recovery solutions for the Reiser File System. Ontrack has provided successful recoveries for the Reiser File System internationally through both in-lab and Remote Data Recovery™ services.
Partner Solutions
Data loss happens every day and all over the world. The loss of business productivity, time, and hard work spent on documents and reports is staggering. Data loss seems to happen at the worst possible time—just when a proposal is due or minutes before an important presentation. When data loss happens, users are frustrated and angry, business operations may grind to a halt, and daily revenue may be severely impacted. While IT administrators work tirelessly to get things back, the results may be poor or out of date.
Therefore to successfully survive a data disaster, the recovery should be left to experienced and qualified professionals. Ontrack realises this important fact and distinguishes itself from other services by concentrating on the details of data recovery. The science of data recovery is split into two fields of discipline; one is in the electronic science where hard drives reside and the other is computer science where data resides. Ontrack pursues both disciplines with equal passion. Ontrack's development group provides recovery solutions for many different data loss situations. Ontrack gets into the science of data recovery and develops its own proprietary tools and methods for hard drives and specialised proprietary software to repair file systems and find lost data. Just as we have with previous file systems, Ontrack has developed the expertise to handle ReiserFS recoveries and keep our customers protected.
Partnering with Ontrack enables you to mitigate data loss when disasters occur. Ontrack realises that time is of the essence when you experience data loss; Ontrack's goal is to get accurate data back to you as fast as possible. When you choose Ontrack, you are partnering with the recovery experts.
