Although most businesses understand the need for a network backup strategy, few appreciate the problems that can be introduced by using an inappropriate system.
Backing up to media like Zip or Jaz disks is fraught with perils. Removable disk drives are not backup devices, nor are they intended as such. They are meant for transferring files between computers. Recordable compact discs are not a viable solution either because a CD will only hold 650MB, which is far short of the gigabytes needed by small businesses.
Tape drives are a better backup solution. But, a single tape drive alone is not sufficient. The main problem is someone has to stand over the drives in order to change tapes. Plus, most backups need to be run during off-hours. Running a backup while users are accessing a system is dangerous. You never know what state your files are in when they are backed up and this slows down server performance. Even when the network can be backed up to a single tape, someone still has to make sure a fresh tape is installed every morning.
The best way to ensure that a backup session can run unattended is to use automation. A number of manufacturers have built tape autoloaders that will switch tapes automatically. Together with software designed for unattended backup, an autoloader is the best way to insure that important data is protected, whether or not someone is there making sure it takes place.
A tape autoloader is a single tape drive mounted in a cabinet with a robotic arm that swaps tapes. Autoloaders can hold as few as seven tapes or as many as 22. If a backup fills more than a single tape the robot can change tapes under control of the backup software.
A step up from autoloaders are tape libraries. With two or more tape drives, libraries can record multiple data streams shortening backup time. Having two tape drives opens up the possibility of making copies of your backups for extra protection. Autoloaders can also be programmed to automatically insert a cleaning cartridge into the tape drive after every few hours of run time. This insures that the often forgotten cleaning procedure takes place. In short, autoloaders make sure that your business' data is preserved while saving you labor costs.
HOW MUCH AUTOLOADER DO YOU NEED?
The number of tape slots and media capacity are what primarily differentiates autoloaders. A large number of slots mean there are more tapes available for backup. This lets you backup more data or backup more sessions without having to change tapes. Higher capacity tapes let you use fewer tapes for each backup.
Autoloaders are available for nearly any kind of tape drive. Select the tape drive for its performance characteristics, such as tape capacity and speed. All capacities specified in this article are native, with no compression applied. Tape drive manufacturers will often state compressed capacities of 2 to 1. Meaning, a 50GB native capacity would be listed as 100GB compressed. However, real compressed capacity can vary from 1 to 1 (no compression) to as much as 10 to 1 depending on the type of data.
Another option to consider is whether to go with a slot or magazine loading autoloader. Slot-loading lets you add tapes individually, either directly into the autoloader's tape slots or through a single mail slot. It can be tedious, but they make it easy to add and remove individual tapes.
A magazine loading autoloader uses a carrier to load and unload all the tapes at once. For example, if an autoloader uses ten-tape magazines each magazine can hold a week's worth of backups at once. This allows you to swap a week's backup at one time. You can also use the magazines to store several backup sets outside the autoloader. These autoloaders are inconvenient when you just need to replace a single tape, but they are more convenient when you need to keep groups of tapes together.
THE TAPE DRIVES
Half-inch tape is one of the most popular formats and offers an array of choices. Quantum and Tandberg make half-inch tape drives in three formats: DLT-4000, DLT-7000, and DLT-8000. These tapes will store 20, 35, and 40GB respectively. In addition to high capacity, Quantum's DLT tape drives also offer high performance. Assuming your hard disk drives and computers can feed data to the tape drive fast enough, a Quantum DLT drive will record data at speeds up to 5MB per second or 300MB per minute. If you have a lot of data on a RAID system to preserve every night, a fast DLT tape drive insures that the backup will be completed by morning.
An alternate DLT technology is the DLT1 tape drive from Benchmark Tape Systems. Although based on the same DLT tape drives and tapes used by Quantum, DLT1 is a different incompatible format. DLT1 offers the same capacity as a DLT-8000 tape drive but at a slower transfer rate of 180MB per minute, and reduced cost. DLT1 drives are good choices when you need a large capacity tape drive but either have less data to backup each night or your disk storage is not fast enough to take full advantage of DLT's maximum speed.
You can also choose to go with 8mm tape. The 8mm drives are made by Sony and Ecrix. Sony's AIT tape drives are relatively high-end products. An AIT-2 tape stores 50GB, the highest capacity you will find in an affordably priced tape drive. AIT-2 also supports lower capacity 25GB and 35GB tapes, so you can economize on these if you have modest backup needs now. You can switch to the higher capacity tapes later on as the need arises. AIT-2 tape drives are also very fast -- 6MB per second or 360MB per minute.
Ecrix's VXA-1 is a relatively new format also based on 8mm tape. The drive has reduced capacity and speed compared to Sony, but the price point is much lower. VXA tapes are available in two capacities, 12 and 33MB with a 3MB per second transfer rate. VXA-1 tape drives also have a unique packet-based recording technology that's designed to improve reliability, especially when moving tape between drives.
The most important feature of 8mm tape drives is its fast access to data, as 8mm tape drives can locate and restore a single file faster than a DLT tape drive. DLT tape drives are faster than an 8mm drive when you need to recover an entire tape but an 8mm drive will be faster at recovering individual files.
Finally, Tandberg offers a unique quarter-inch tape (QIC) format, SLR. SLR capacities are equivalent to that of AIT-2, at up to 50GB with transfer rates up to 5MB per second. SLR tapes are bulkier than 8mm tapes and are more expensive.
The most extensive line of autoloaders comes from ADIC, which makes two DLT autoloaders and two AIT autoloaders. Both of the AIT autoloaders can be upgraded with additional tape drives into true libraries.
The FastStor 7 is ADIC's smallest and least expensive autoloader. It holds a single DLT tape drive and seven tapes. The seven-tape capacity allows you to keep up to a week's worth of backups near-line or to make an unattended backup of as much as 280GB of data.
The FastStor 22 is twice the physical size of the FastStor 7 and holds 22 tapes, which are enough to capture nearly a month's worth of backups. The FastStor 22 also has a 23rd slot that can be used for tape cartridge swapping or to hold a cleaning cartridge. The autoloader can be programmed to clean the tape drive after a predetermined amount of time. There is also an optional bar code reader for larger scale environments that label tapes.
ADIC also makes two AIT tape libraries that can be fitted with one or two AIT tape drives. The VLS-AIT library holds 11 tapes putting it squarely between the FastStor 7 and FastStor 22 in capacity. ADIC's Scaler 220 holds 20 tapes and also includes a barcode reader for quick identification of tapes.
ADIC's autoloaders demonstrate the difference between magazine and slot-loading tape robots. The FastStor DLT autoloaders both use a slot-loading mechanism. Users can open the unit and load the front slots one by one or use the mail slot for individually loading slots in the back of the unit. ADIC's AIT libraries, however, use 11- or 10-tape magazines. When you load, you must move all the tapes at once.
Graphiti Associates, a graphics design bureau in Seattle, WA, used to backup all their files to a combination of CD-R and DDS tape. The CD was used for long term archives and the DDS tape for short-term. Graphiti was using a DDS-2 tape drive with just a 4GB capacity per tape. In the words of Michelle Fujimoto, Graphiti's principal, "We didn't like the DDS tapes because we kept having to swap them."
By switching to a FastStor 22 with a DLT-8000 tape drive, Graphiti improved their backup procedure in two ways. First, the DLT-8000 drive stores ten times as much data on a single tape as their previous solution. Second, the FastStor 22 holds 22 tapes, eliminating the need to search for a particular backup tape. "In the past, we've needed to go back as much as a month to retrieve a backup up file. We normally keep three week's worth of backups. They all reside in the FastStor eliminating the need to search for tapes."
Like ADIC, Overland Data offers a selection of autoloaders suitable for small businesses. The LoaderXpress holds a single DLT tape drive and five to 10 tapes in a single magazine. This is sufficient for one or two week's worth of backups. The magazines are solid plastic and interchangeable. The LoaderXpress supports all DLT tape formats.
Overland Data also offers the AIT LibraryPro, an AIT library that holds one or two drives and up to 17 tapes. The LibraryPro has both a mail-slot for loading and unloading single tapes and a magazine system to change all the tapes at once. The LibraryPro is expandable, allowing additional tape cabinets to be stacked on top of the first unit as capacity needs grow, an unusual feature found on many Overland Data tape libraries.
Another optional innovation from Overland Data is their Web TLC, a network-based control device for Overland Data's autoloaders and libraries. The Web TLC is a small black box that connects to a serial port on the LoaderXpress or LibraryPro. It enables you to control and monitor the autoloaders over the Internet and reports any problems automatically. The Web TLC can be a valuable tool when running an unattended backup.
Tandberg's SLR Autoloader
Tandberg is one of the few companies that make both drives and automation systems for backup purposes. For the company's SLR tape drives there is the Tandberg SLR Autoloader. SLR drives are linear, meaning the record/playback head remains fixed as the tape is drawn past it. Linear tape drives have fewer moving parts than 8mm tape drives and usually have a single motor. However, SLR tape drives run hot. Tapes have a large aluminum plate that keeps them rigid and acts as a heat sink. SLR autoloaders have to have large fans to draw the heat away from the tape drive, especially during prolonged use.
Tandberg's SLR Autoloader holds eight tapes and a single drive. The Autoloader will accommodate any of Tandberg's SLR tape drives. The SLR 100 offers the highest capacity. The tapes are loaded in eight-slot magazines. Eight tapes will let your run a full week of backups unattended or do one backup of as much as 400GB of data.
Ecrix VXA-1 Autopak
VXA-1 is a new tape format that is based on the proven 8mm tape format. It was originally designed as a replacement for 4mm tape but its high capacity and speed make it competitive with tape drives twice as expensive.
The Autopak is Ecrix's low-end automation system for VXA tape drives. It holds one or two tape drives so it can be configured as a true library. It holds 15 cassettes in a removable magazine, enough for two weeks of backups. There is a barcode option and the loader can be installed in a rack or kept on a tabletop.
Telecom Software Enterprises, a Greenwood Village, Colo., maker of IP telephony software switched to Ecrix's Autopak autoloader after struggling with a DDS-2 tape drive that held only 4GB of data.
According to John Maxson, who maintains Telecom's infrastructure, the standalone tape drive was seriously affecting the company's confidence in its data storage. "Our backup requirements had grown to 10GB per day. With the old DDS tape, we either had to leave someone behind to swap tapes, or live with the fact that we didn't have a complete backup." All too often, replacing a fresh tape for the nightly backup was neglected, leaving the company stranded with little protection if the system crashed.
The Ecrix Autopack solved both the company's backup problems. First, the high capacity of the tape meant that a single tape could hold a full backup session. Second, the autoloader made sure a new tape was used each and every night. "We keep two weeks worth of backups near-line now," says Maxson, "and the Ecrix tapes have enough storage capacity to keep pace with our company as it grows."