Most tape formats detail the maximum native 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 barely meet great conditions, you'll not be able to achieve the mentioned maximums. As an example, the type of info you are trying to compress has a great effect on capacity. Some kinds of info just do not compress well.
If you're seeing noticeably lower capacity, it could be due to one or two of the following reasons:
The tape drive's data compression isn't enabled. Tape drives that compress info use compression by default. However , there are tactics for tape drive compression to be turned off thru the backup application. Check your application to work out if it's got a setting for hardware compression. Usually, you'll be wanting to confirm hardware compression is turned on.
You could be writing info that doesn't compress well.Maximum capacities for tapes are typically based totally on a median 2:1 data compression proportion (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some sorts of information compress at a higher proportion; others compress at a lower proportion. For instance, executable files and graphics files often do not compress well.
The tape drive could be attempting to compress data that's already compressed.If your backup programme compresses data before sending it to the tape drive, the tape drive cannot compress it further. Actually the additional attempt at compression may very well cause the data to expand. Do not use both software and hardware information compression. If the tape drive is about to compress information, 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're backing up a high percentage of already compressed files,eg MP3, AVI, and JPG files, then you will not see any farther compression at the tape drive level. Actually as the info is compressed twice, it may very well expand. Try turning off hardware compression and software compression in your backup application.
Your system may not be able to stay abreast of the tape drive.If your PC does not send information to the tape drive as speedily as the tape drive can write information to the tape, the tape drive stops and waits for the PC. Each time the tape drive stops, it writes gap tracks (tracks of undefined data) to aid in repositioning when more data becomes available. If the tape drive has to stop and restart often, tape capacity is influenced. Check if there are transfer bottlenecks in your system. For instance, if you're backing up data over a 100bT network, a standard transfer rate might be far slower 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 newest servers and LTO5 drives, a full 6Gb/sec should be made available to the tape drive.
Your tape might be ready for retirement.If you are using a tape that is well worn, the tape drive might be performing high numbers of rewrites to fix errors. Over the top rewrites cut back the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your device , employing a new tape, and ensure you are using good quality info cartridges.
Your tape drive may need cleaning.A buildup of debris in the tape drive or on the recording heads can cause increased mistake rates and rewrites. If you haven't cleaned your tape drive latterly, try cleaning it with the appropriate Cleaning Cartridge for your tape drive model.
Because real world systems barely meet great conditions, you'll not be able to achieve the mentioned maximums. As an example, the type of info you are trying to compress has a great effect on capacity. Some kinds of info just do not compress well.
If you're seeing noticeably lower capacity, it could be due to one or two of the following reasons:
The tape drive's data compression isn't enabled. Tape drives that compress info use compression by default. However , there are tactics for tape drive compression to be turned off thru the backup application. Check your application to work out if it's got a setting for hardware compression. Usually, you'll be wanting to confirm hardware compression is turned on.
You could be writing info that doesn't compress well.Maximum capacities for tapes are typically based totally on a median 2:1 data compression proportion (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some sorts of information compress at a higher proportion; others compress at a lower proportion. For instance, executable files and graphics files often do not compress well.
The tape drive could be attempting to compress data that's already compressed.If your backup programme compresses data before sending it to the tape drive, the tape drive cannot compress it further. Actually the additional attempt at compression may very well cause the data to expand. Do not use both software and hardware information compression. If the tape drive is about to compress information, 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're backing up a high percentage of already compressed files,eg MP3, AVI, and JPG files, then you will not see any farther compression at the tape drive level. Actually as the info is compressed twice, it may very well expand. Try turning off hardware compression and software compression in your backup application.
Your system may not be able to stay abreast of the tape drive.If your PC does not send information to the tape drive as speedily as the tape drive can write information to the tape, the tape drive stops and waits for the PC. Each time the tape drive stops, it writes gap tracks (tracks of undefined data) to aid in repositioning when more data becomes available. If the tape drive has to stop and restart often, tape capacity is influenced. Check if there are transfer bottlenecks in your system. For instance, if you're backing up data over a 100bT network, a standard transfer rate might be far slower 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 newest servers and LTO5 drives, a full 6Gb/sec should be made available to the tape drive.
Your tape might be ready for retirement.If you are using a tape that is well worn, the tape drive might be performing high numbers of rewrites to fix errors. Over the top rewrites cut back the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your device , employing a new tape, and ensure you are using good quality info cartridges.
Your tape drive may need cleaning.A buildup of debris in the tape drive or on the recording heads can cause increased mistake rates and rewrites. If you haven't cleaned your tape drive latterly, try cleaning it with the appropriate 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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