Archive for August 12th, 2012

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 perfect conditions.

Because realworld systems seldom meet perfect conditions, you may be unable to achieve the mentioned maximums. As an example, the sort of data you are attempting to compress has a great effect on capacity. Some types of info just do not compress well.

If you’re seeing noticeably lower capacity, it could be due to one or more of the following reasons:

The tape drive’s information compression isn’t enabled. Tape drives that compress information use compression by default. However , there are ways for tape drive compression to be turned off thru the backup application. Check your application to determine if it has a setting for hardware compression. In most situations, you will be wanting to ensure hardware compression is turned on.

You may be writing information that doesn’t compress well.Maximum capacities for tapes are usually based primarily on an average 2:1 data compression proportion (or 2.5:1 for Exabyte M2 drives and some Sony AIT drives). Some types of data compress at a higher proportion; others compress at a lower ratio. As an example, executable files and graphics files often don’t compress well.

The tape drive may be attempting to compress info 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. In reality the extra attempt at compression may cause the info to expand. Do not use both software and hardware information compression. If the tape drive is ready 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 are backing up a high percentage of already compressed files, such as MP3, AVI, and JPG files, then you won’t see any farther compression at the tape drive level. In reality 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 keep up with the tape drive.If your computer doesn’t send information to the tape drive as fast as the tape drive can write info to the tape, the tape drive stops and waits for the computer. Each time the tape drive stops, it writes gap tracks (tracks of uncertain data) to help in repositioning when more data 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. For example, if you are backing up data over a 100bT network, a common transfer rate could be far slower 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 newest servers and LTO5 drives, a full 6Gb/sec should be supplied to the tape drive.

Your tape might be ready for retirement.If you’re using a tape that’s well worn, the tape drive could 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 correct cleaning tape for your gadget using a new tape, and ensure you are using high quality information cartridges.

Your tape drive may need cleaning.A buildup of waste in the tape drive or on the recording heads can end up in increased blunder rates and rewrites. If you have not cleaned your tape drive lately, try cleaning it with the right Cleaning Cartridge for your tape drive model.

The writer is a lto repair expert running a local economy specializing in lto repairs and network attached storage.