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 perfect conditions.
Because real-world systems rarely meet great conditions, you may struggle to achieve the mentioned maximums. As an example, the kind of data you are endeavoring to compress has a great effect on capacity. Some kinds of data just do not compress well.
If you're seeing noticeably 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 data use compression by default. Nevertheless there are tactics for tape drive compression to be turned off through the backup application. Check your application to determine if it's got a setting for hardware compression. In most cases, you will want to make sure hardware compression is turned on.
You may be writing data that does not compress well.Maximum capacities for tapes are typically based primarily on a median 2:1 data compression ratio (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some sorts of data compress at a higher ratio; others compress at a lower proportion. As an example, executable files and graphics files typically do not compress well.
The tape drive might be trying to compress info that is already compressed.If your backup program compresses information before sending it to the tape drive, the tape drive cannot compress it further. In fact , the extra attempt at compression may actually cause the data to expand. Don't use both software and hardware data compression. If the tape drive is about to compress data, 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 thru the tape drive's hardware compression chip. If you're backing up a high proportion of already compressed files, for example MP3, AVI, and JPG files, then you won't see any farther compression at the tape drive level. In reality 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 keep up with the tape drive.If your computer does not 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 PC. Every time the tape drive stops, it writes gap tracks (tracks of undefined data) to help in repositioning when more info becomes available. If the tape drive has to stop and restart frequently, tape capacity is affected. 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 might be far less quickly than you predict. In this case, changing the network to at least 1GbE and for should improve both transfer rates and tape capacity. For the latest servers and LTO5 drives, a full 6Gb/sec should be supplied to the tape drive.
Your tape might be prepared for retirement.If you use a tape that is well worn, the tape drive could be performing high numbers of rewrites to correct errors. Over the top rewrites reduce the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your gadget employing a new tape, and ensure you are using top quality data cartridges.
Your tape drive may require cleaning.A building up of debris in the tape drive or on the recording heads can cause increased blunder rates and rewrites. If you have not cleaned your tape drive recently, try cleaning it with the appropriate Cleaning Cartridge for your tape drive model.
Because real-world systems rarely meet great conditions, you may struggle to achieve the mentioned maximums. As an example, the kind of data you are endeavoring to compress has a great effect on capacity. Some kinds of data just do not compress well.
If you're seeing noticeably 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 data use compression by default. Nevertheless there are tactics for tape drive compression to be turned off through the backup application. Check your application to determine if it's got a setting for hardware compression. In most cases, you will want to make sure hardware compression is turned on.
You may be writing data that does not compress well.Maximum capacities for tapes are typically based primarily on a median 2:1 data compression ratio (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some sorts of data compress at a higher ratio; others compress at a lower proportion. As an example, executable files and graphics files typically do not compress well.
The tape drive might be trying to compress info that is already compressed.If your backup program compresses information before sending it to the tape drive, the tape drive cannot compress it further. In fact , the extra attempt at compression may actually cause the data to expand. Don't use both software and hardware data compression. If the tape drive is about to compress data, 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 thru the tape drive's hardware compression chip. If you're backing up a high proportion of already compressed files, for example MP3, AVI, and JPG files, then you won't see any farther compression at the tape drive level. In reality 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 keep up with the tape drive.If your computer does not 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 PC. Every time the tape drive stops, it writes gap tracks (tracks of undefined data) to help in repositioning when more info becomes available. If the tape drive has to stop and restart frequently, tape capacity is affected. 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 might be far less quickly than you predict. In this case, changing the network to at least 1GbE and for should improve both transfer rates and tape capacity. For the latest servers and LTO5 drives, a full 6Gb/sec should be supplied to the tape drive.
Your tape might be prepared for retirement.If you use a tape that is well worn, the tape drive could be performing high numbers of rewrites to correct errors. Over the top rewrites reduce the tape's capacity. Try cleaning the tape drive with the right cleaning tape for your gadget employing a new tape, and ensure you are using top quality data cartridges.
Your tape drive may require cleaning.A building up of debris in the tape drive or on the recording heads can cause increased blunder rates and rewrites. If you have not cleaned your tape drive recently, 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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