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 got under great conditions.
Because realworld systems seldom meet great conditions, you'll struggle to achieve the specified maximums. As an example, the kind of information you are trying to compress has a great effect on capacity. Some types of information just do not compress well.
If you are seeing noticeably lower capacity, it may be due to one or more of the following reasons:
The tape drive's info compression isn't enabled. Tape drives that compress info use compression by default. Nevertheless there are techniques for tape drive compression to be turned off thru the backup application. Test your application to see if it has a setting for hardware compression. In most cases, you will be wanting to make sure hardware compression is turned on.
You could be writing data that doesn't compress well.Maximum capacities for tapes are usually based primarily on a median 2:1 data compression proportion (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some types of info compress at a higher ratio; others compress at a lower proportion. For instance, executable files and graphics files often don't compress well.
The tape drive might be attempting to compress data that is already compressed.If your backup program compresses data before sending it to the tape drive, the tape drive can't compress it further. In fact , the extra attempt at compression may cause the info to expand. Don't use both software and hardware data compression. If the tape drive is set to compress information, switch off the software compression in your backup application.In the same way, compressed files on your hard disk won't compress any farther when fed thru the tape drive's hardware compression chip. If you're backing up a high share of already compressed files,eg MP3, AVI, and JPG files, then you will not see any further compression at the tape drive level. In fact , as the information is compressed twice, it may actually expand. Try turning off hardware compression and software compression in your backup application.
Your system may not be able to stay alongside of the tape drive.If your personal computer doesn't send data to the tape drive as fast as the tape drive can write data to the tape, the tape drive stops and waits for the computer. Everytime the tape drive stops, it writes gap tracks (tracks of undefined info) to aid in repositioning when more information becomes available. If the tape drive has to stop and restart frequently, tape capacity is influenced. Check if there are transfer bottlenecks in your system. For instance, if you're backing up info over a 100bT network, a standard transfer rate could be much more slowly than you predict. In this example, changing 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 made available to the tape drive.
Your tape may be prepared for retirement.If you use a tape that's well worn, the tape drive may be performing high numbers of rewrites to fix mess ups. Over the top rewrites scale back the tape's capacity. Try cleaning the tape drive with the proper cleaning tape for your gadget using a new tape, and ensure you are using good quality information cartridges.
Your tape drive may require cleaning.A buildup of debris in the tape drive or on the recording heads can lead to increased mistake rates and rewrites. If you haven't cleaned your tape drive lately, try cleaning it with the correct Cleaning Cartridge for your tape drive model.
Because realworld systems seldom meet great conditions, you'll struggle to achieve the specified maximums. As an example, the kind of information you are trying to compress has a great effect on capacity. Some types of information just do not compress well.
If you are seeing noticeably lower capacity, it may be due to one or more of the following reasons:
The tape drive's info compression isn't enabled. Tape drives that compress info use compression by default. Nevertheless there are techniques for tape drive compression to be turned off thru the backup application. Test your application to see if it has a setting for hardware compression. In most cases, you will be wanting to make sure hardware compression is turned on.
You could be writing data that doesn't compress well.Maximum capacities for tapes are usually based primarily on a median 2:1 data compression proportion (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some types of info compress at a higher ratio; others compress at a lower proportion. For instance, executable files and graphics files often don't compress well.
The tape drive might be attempting to compress data that is already compressed.If your backup program compresses data before sending it to the tape drive, the tape drive can't compress it further. In fact , the extra attempt at compression may cause the info to expand. Don't use both software and hardware data compression. If the tape drive is set to compress information, switch off the software compression in your backup application.In the same way, compressed files on your hard disk won't compress any farther when fed thru the tape drive's hardware compression chip. If you're backing up a high share of already compressed files,eg MP3, AVI, and JPG files, then you will not see any further compression at the tape drive level. In fact , as the information is compressed twice, it may actually expand. Try turning off hardware compression and software compression in your backup application.
Your system may not be able to stay alongside of the tape drive.If your personal computer doesn't send data to the tape drive as fast as the tape drive can write data to the tape, the tape drive stops and waits for the computer. Everytime the tape drive stops, it writes gap tracks (tracks of undefined info) to aid in repositioning when more information becomes available. If the tape drive has to stop and restart frequently, tape capacity is influenced. Check if there are transfer bottlenecks in your system. For instance, if you're backing up info over a 100bT network, a standard transfer rate could be much more slowly than you predict. In this example, changing 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 made available to the tape drive.
Your tape may be prepared for retirement.If you use a tape that's well worn, the tape drive may be performing high numbers of rewrites to fix mess ups. Over the top rewrites scale back the tape's capacity. Try cleaning the tape drive with the proper cleaning tape for your gadget using a new tape, and ensure you are using good quality information cartridges.
Your tape drive may require cleaning.A buildup of debris in the tape drive or on the recording heads can lead to increased mistake rates and rewrites. If you haven't cleaned your tape drive lately, try cleaning it with the correct Cleaning Cartridge for your tape drive model.
About the Author:
The writer is a lto repair expert running a local enterprise focusing on lto repairs and network attached storage.
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