Choosing the most appropriate data storage and data backup services

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Choosing the most appropriate data storage and data backup services

The boom in the IT sector has led to a rising demand for data storage and data backup services. However, choosing the most appropriate services for your company requires a strategy of its own

The tremendous growth of the IT industry has created an increasing demand for data storage capacity and consequently, better data backup services. Developing a successful backup strategy begins with a carefully planned backup needs analysis. The administrator first identifies the company's total backup needs and then matches those needs to the appropriate backup hardware and software.

There are various hardware technologies available for data backup. The most common and inexpensive one is the QIC or Quarter Inch Cartridge. Although rather slow, it is ideal for small businesses. Medium-level enterprises might want to consider DAT or Digital Audio Tape. Much faster than QIC, DAT tapes can also store more data. Businesses with multiple offices and larger server capacities should adopt technologies like DLT or Digital Linear Tape. DLT tapes have capacities up to 30Gb and are much more reliable. There are also high capacity proprietary solutions available from companies like OnStream.

While choosing data backup software, it is important to assess the quality of technical support available and the reliability of the backup device.

Although not quite as visible as many other operations, data backup is just as important to the success and well being of the organisation.

The tremendous growth of the IT industry has created an increasing demand for data storage capacity and consequently, better data backup services. Fuelled by the ever-expanding growth of Internet-related technologies, electronic messaging, multimedia, Online Transaction Processing (OLTP) and other data-intensive applications, the enterprise backup and storage market is expected to expand rapidly during the next two years.

Why are backups essential?

The backup process copies important information (in many companies, this is vitally important information) onto magnetic tape or other disks. This enables the restoration of anything, from one file to the entire system, should the need arise. Backups have helped companies recover from data losses caused by power surges and outages, static electricity, lightning strikes, terrorist bombings, user errors, viruses and even spilled coffee.

Data recovery tools and services do exist. But they are limited and can be expensive. Using these services, users might be able to retrieve some of the lost data. But it is unlikely you will ever retrieve all of the lost data. Complex applications, network configurations, customised set-ups and passwords may be impossible to retrieve. The sudden loss of a mission critical server that stores and maintains corporate records and data (one of a company's most valuable assets) can be financially disastrous. In most companies just the downtime before recovery could prove too costly. A well-designed backup system safeguards crucial information, providing the most efficient insurance against disaster.

Developing a successful backup strategy begins with a carefully planned backup needs analysis. The administrator first identifies the company's total backup needs and then matches those needs to the appropriate backup hardware and software. In many companies as much as 40% of the data changes every month. Ultimately, all company data and programs should be backed-up so that the entire system can be restored in the event of a catastrophic disaster. The total amount of data to be backed-up indicates the capacity required of the drive and the media. If planned backups will be unattended, then the selected backup device must have enough capacity to hold the full amount of information to be backed-up.

Another crucial factor to consider is the performance of the backup kit, both hardware and software. System administrators typically perform backups when user demands on the server are at their lowest. Ideally, this time period, often called the backup window, is when user access can be restricted or the server shut down. For many companies with worldwide operations accessing their servers, no clear backup window exists. In such an instance, the administrator will have to perform the backup while the system is still in use. This often leads to some degradation in overall performance. Where a backup window does exist, the selected device's backup rate, together with the appropriate backup software, must be able to accomplish the task within the time available. The amount of data that needs to be backed up, along with the time available for doing it, often determines the type of media and software that can be used.

Performance is determined by dividing the amount of information (in gigabytes) that must be backed up by the size of the backup window (in hours). This simple calculation yields the required performance as an overall transfer rate expressed in gigabytes per hour.

Technologies for data backup?

Currently, there are three types of backup technologies that are frequently used. The oldest and most common among these is Quarter Inch Cartridge (QIC). These drives have the lowest capacities and slowest transfer speeds. QIC drives meet the half-height form factor of desktop computers. QIC tapes are virtually industry-standard for standalone machines. However, with capacities limited to 1.2Gb, they are not generally suitable for backing up servers with 2Gb or more storage capacity - a capacity exceeded by ordinary desktop PCs nowadays.

Low capacities and slow speeds are not the only disadvantages of QIC drives. They also require regular maintenance. Like normal audio tape heads in consumer tape recorders, QIC drive heads must be cleaned regularly. This is particularly important if the tapes themselves are being reused often.

QIC drives are slow, not just because of their overall data transfer rate. Most of them only allow sequential access to data. Therefore, it is not possible to selectively replace backed-up data. Despite these disadvantages, QIC drives are still very popular because they offer excellent value for money. For many small businesses for whom cost is a big concern, QIC drives offer the best solution. Even for larger enterprises, QIC can be useful for short-term archiving.

The second most popular backup hardware format is DAT (Digital Audio Tape). DAT drives are usually the appropriate choice for servers with 2Gb to 8Gb capacity. A high density DAT tape can store up to 16Gb of data with efficient compression. Like QIC drives, DAT drives also offer good value for money. In addition to bigger capacities, they offer better reliability and, more importantly, random access to stored data.

So, who should consider using DAT for backups? Medium-level enterprises who have modest backup windows and budgets are ideally suited for DAT backups. Even fast growing small businesses with increasing backup requirements might want to consider migrating to DAT at some stage from QIC or other less capable solutions.

One of the Goliaths among backup technologies is Digital Linear Tape (DLT). These drives can store up to 30Gb of data. The basic DLT technology has been around for a decade. It was first introduced by Digital Equipment Corporation (DEC). When coupled with RAID technology, arrays of identical DLT drives offer a high degree of fault tolerance and data accuracy. In addition to much higher data backup capabilities, the basic DLT design is inherently more reliable than those of DLT's counterparts from the older technologies. In DAT and other helical scan drives, the tape is wound tightly around a drum and moves through a complex tape path, resulting in stress and abrasion to the tape and the heads. DLT tape operates at a lower constant tension. Therefore its life span is much higher.

The technologies mentioned above are not the only ones available for backup purposes. Many companies offer proprietary backup solutions. For instance, OnStream's tape backup kit now offers capacities up to 70Gb with compression - a real competitor to the older and more expensive DLT technology. However, those who intend to adopt such apparently cheaper proprietary technologies must also enquire about hidden costs and the level of technical support available in each region.

Deciding the type of backup device is only one step towards solving the problem. After this, the system administrator has to adopt a schedule and methodology for creating the backups. For instance, if the backup windows are really small or non existent, the system administrator may opt for a dedicated network just for backup purposes. This dedicated network, which is completely independent of the normal LAN, has two major advantages. Firstly, it almost completely eliminates the need for a backup window as the backup process can be completed while users are still logged on to the network. Secondly, because there is a dedicated channel for transferring backup files, the bandwidth on the main LAN remains untouched and performance is not affected. This dedicated network can be constructed using regular networking cables or fibre channel cables. Of course, high bandwidth technologies, like fibre channels, tend to be much more expensive.

Choosing the right hardware is only one half of the backup solution. If you do not have fully tested software to run on the appropriate platforms, even the most robust hardware set-up may not be able to prevent loss of data. Like hardware, backup software is available from a number of different vendors to suit all needs and budgets. Quite a few of the advanced backup software packages are offered by the major hardware vendors themselves. And they are available for most popular server operating systems like Windows NT and UNIX.

Backup Software

In most companies, the backup process is done remotely without human intervention. Therefore, more than anything else, a backup software package must be able to schedule all the tasks involved. At times specified by the system administrator, the software must initiate the backup process. The software must be capable of continuously monitoring the entire process and reporting any problems it encounters. If the problem is a software one (such as conflict with another application), the package must be intelligent enough to recognise it as such and take the appropriate measures to correct it. Even some hardware problems can be fixed by good quality backup software.

Most backup software vendors offer regular updates for their products. However, not all the updates may be appropriate for every organisation. Therefore, it is absolutely essential to check the quality of technical support available before purchasing the product. Most of the major vendors of backup software support the popular UNIX platforms, NT, and NetWare. If you are backing up data resources on other platforms you may find your choice is restricted.

Data backup is an integral part of any organisation's IT infrastructure. Although not quite as visible as many other operations, data backup is just as important to the success and well being of any organisation. As the amount of data in an organisation increases, the scale of the backup solution must keep pace. As the world moves to a 24 x7 web-enabled e-commerce model, downtime for backup and restore must be kept as close to zero as practicable. Backup speed can become a critical issue for business competitiveness.


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This was first published in July 1999

 

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