Knowledgebase

Tape Drive Common Causes of Failure

1. Dusty Environment
2. Power Fluctuation
   (a)  Frequency & (b) Voltage fluctuation
3. Improper Storage or Mishandling of Media
   Improper storage or mishandling of media is one of the common causes of backup failure. While DLTtape media is designed for durability and reliability, there are some basic steps that can be taken to avoid damage to the cartridge and media. It's important to respect media manufacturers' recommendations in terms of media inspection, handling and storage requirements.  Tapes that have been over used can also cause problems. DLTtape media is designed for heavy-duty cycle environments and lasts considerably longer -- it's specified for 5000 insertions -- but it's still important for an IT administrator to monitor media usage.
   
   System hardware and software can also be an issue: Simple things like exceeding the specified SCSI cable length or having a SCSI terminator missing can cause the backup to fail. So it's important that an administrator makes sure the system is compliant with the standards required for the level of SCSI Interface in place.
4. Tape Management Issue
   Tape management, unfortunately, is nonexistent for many of the popular tape and system formats used for mission critical businesses today. Without a formal tape management system and methodology all tape processing including the tape backups are subject to the unknown quality of the media being used. Tape must be managed for adequate quality in use. For tape, temporary errors often lead to permanent errors that relate to job failures. The idea is to remove and replace the failing tapes before the permanent error occurs and causes a job failure.
5. Human Mistakes like wrong cartridge, wrong policy etc. and drive/media Failures.  

Tape Life
BEI recommends using 4mm and 8mm tapes no more than 50 times before retiring the tape from active use. While tape manufacturers may state that their product can be used many more times than this, experience has shown that it is better to plan on a life cycle where restorations from tape are more predictable.

In supporting hundreds of customers with 4mm and 8mm tape drives, the most common restore problem is dirty read heads, then dirty write heads and then bad tape. A DAT drive will attempt to write 127 times before it fails with an I/O error! Our advice is to implement a program of constantly replacing aged tape before it creates problems.

An excellent method to accomplish tape replacement is to purchase enough tape to perform a month's worth of backups and then replace it after two years. Each tape would have about 25 uses and the net cost would be less than 50 cents a use. The additional benefit of being able to restore any file from the previous 30 days of backups will decrease significantly the opportunity for a backup or restore failure. One customer reported using 3 tapes for grandfather, father, son backups until a tape failed -- somewhere around 30-60 days, and then would replace the failed tape!

Type of Tape
Use only certified data grade 4mm and 8mm cassettes. Data grade cassettes will extend the life of your tape drive's read and write heads! Data grade tapes are burnished five times and then coated with ceramic particles to further smooth the tape. Audio grade media is not finished as finely. At the other end of the spectrum is cleaning tape, which is simply unburnished tape.

Both 4mm and 8mm tape drives require regular and systematic preventative maintenance to prevent backup and restore failures. These types of tape drive continuously pass tape over the heads which causes wear and accumulates residue on the recording and playback heads. While you cannot prevent wear from occurring, regular cleaning will eliminate accumulated residue, a principle cause of read or write failures.

Most manufactures suggest using a cleaning cassette about every 30 - 50 hours of use. This includes backup, restore and verify operations.

To clean a 4mm or 8mm drive, purchase a data grade-cleaning cassette and simply insert it into the drive. The tape drive will automatically start a cleaning cycle that takes 1 to 2 minutes and then will eject the tape. The cassette has special holes in the case, which program the drive to go through a cleaning cycle.

A cleaning cassette cannot be reused. When the cleaning tape reaches the end of the tape, it is completely used up. The next time the cleaning tape is inserted into the drive, it will be immediately ejected. This is the only indication that a cleaning tape has reached the end of its "life" short of keeping exact count of how many times the tape has been used.