Most tape formats detail the maximum local capacity (without compression) and the maximum compressed capacity. These figures are approximate maximum capacities for the tape drive and these maximums are obtained under ideal conditions.
Because real world systems rarely meet great conditions, you can be unable to achieve the mentioned maximums. For instance, the type of info you are attempting to compress has a great effect on capacity. Some types of info just don't compress well.
If you are seeing significantly lower capacity, it may be due to one or more of the following reasons:
The tape drive's information compression is not enabled. Tape drives that compress information use compression by default. However , there are techniques for tape drive compression to be turned off thru the backup application. Test your application to work out if it has a setting for hardware compression. In most cases, you'll be wanting to make sure hardware compression is turned on.
You may be writing data that doesn't compress well.Maximum capacities for tapes are typically based primarily on a standard 2:1 info compression ratio (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some types of info compress at a higher proportion; others compress at a lower ratio. For instance, executable files and graphics files typically don't compress well.
The tape drive may be making an attempt to compress data that's already compressed.If your backup program compresses info before sending it to the tape drive, the tape drive can't compress it further. Actually the extra attempt at compression may actually cause the info to grow. Do not use both software and hardware information compression. If the tape drive is about to compress info, turn off the software compression in your backup application.In the same way, compressed files on your hard disk won't compress any further when fed through the tape drive's hardware compression chip. If you are backing up a high share of already compressed files,eg MP3, AVI, and JPG files, then you won't see any farther compression at the tape drive level. In fact , as the info is compressed twice, it may expand. Try turning off hardware compression and software compression in your backup application.
Your system may be unable to stay alongside of the tape drive.If your personal computer doesn't send info to the tape drive as fast as the tape drive can write information to the tape, the tape drive stops and waits for the computer. Each time the tape drive stops, it writes gap tracks (tracks of undefined data) to help in repositioning when more information becomes available. If the tape drive has to stop and restart often, tape capacity is affected. Check if there are transfer bottlenecks in your system. As an example, if you are backing up info over a 100bT network, a standard transfer rate could be far less quickly than you are expecting. In this situation, converting the network to at least 1GbE and for should improve both transfer rates and tape capacity. For the most recent servers and LTO5 drives, a full 6Gb/sec should be supplied to the tape drive.
Your tape could be prepared for retirement.If you are using a tape that's well worn, the tape drive might be performing high numbers of rewrites to correct mess ups. Over the top rewrites scale back the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your machine employing a new tape, and make sure you are using good quality info cartridges.
Your tape drive may need cleaning.A buildup of waste in the tape drive or on the recording heads can cause increased error rates and rewrites. If you haven't cleaned your tape drive latterly, try cleaning it with the right Cleaning Cartridge for your tape drive model.
Because real world systems rarely meet great conditions, you can be unable to achieve the mentioned maximums. For instance, the type of info you are attempting to compress has a great effect on capacity. Some types of info just don't compress well.
If you are seeing significantly lower capacity, it may be due to one or more of the following reasons:
The tape drive's information compression is not enabled. Tape drives that compress information use compression by default. However , there are techniques for tape drive compression to be turned off thru the backup application. Test your application to work out if it has a setting for hardware compression. In most cases, you'll be wanting to make sure hardware compression is turned on.
You may be writing data that doesn't compress well.Maximum capacities for tapes are typically based primarily on a standard 2:1 info compression ratio (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some types of info compress at a higher proportion; others compress at a lower ratio. For instance, executable files and graphics files typically don't compress well.
The tape drive may be making an attempt to compress data that's already compressed.If your backup program compresses info before sending it to the tape drive, the tape drive can't compress it further. Actually the extra attempt at compression may actually cause the info to grow. Do not use both software and hardware information compression. If the tape drive is about to compress info, turn off the software compression in your backup application.In the same way, compressed files on your hard disk won't compress any further when fed through the tape drive's hardware compression chip. If you are backing up a high share of already compressed files,eg MP3, AVI, and JPG files, then you won't see any farther compression at the tape drive level. In fact , as the info is compressed twice, it may expand. Try turning off hardware compression and software compression in your backup application.
Your system may be unable to stay alongside of the tape drive.If your personal computer doesn't send info to the tape drive as fast as the tape drive can write information to the tape, the tape drive stops and waits for the computer. Each time the tape drive stops, it writes gap tracks (tracks of undefined data) to help in repositioning when more information becomes available. If the tape drive has to stop and restart often, tape capacity is affected. Check if there are transfer bottlenecks in your system. As an example, if you are backing up info over a 100bT network, a standard transfer rate could be far less quickly than you are expecting. In this situation, converting the network to at least 1GbE and for should improve both transfer rates and tape capacity. For the most recent servers and LTO5 drives, a full 6Gb/sec should be supplied to the tape drive.
Your tape could be prepared for retirement.If you are using a tape that's well worn, the tape drive might be performing high numbers of rewrites to correct mess ups. Over the top rewrites scale back the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your machine employing a new tape, and make sure you are using good quality info cartridges.
Your tape drive may need cleaning.A buildup of waste in the tape drive or on the recording heads can cause increased error rates and rewrites. If you haven't cleaned your tape drive latterly, try cleaning it with the right Cleaning Cartridge for your tape drive model.
About the Author:
The writer is a lto repair expert running a local business concentrating on lto repairs and network attached storage.
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