Check the life of 4-mm tapes in backup
Although the magnetic medium used in tapes has a service life of more than 10 years, the effective life of a tape is much shorter. According to magnetic media manufacturer Imation, the number of passes through the drive usually determines the life of a tape.
What is different about 4-mm tapes, Imation says, is that each operation actually involves several passes through the mechanism. With 4-mm tape, a cartridge can accumulate six to 12 passes of the tape for each backup, restore or verify operation.
As a result, Imation says, even though a 4-mm tape is rated for 1500 passes, "the maximum number of backup, restore or verify operations which can be expected is actually about 250 under optimum conditions." Since optimum conditions seldom occur in real-life data centers, Imation recommends taking 4-mm tapes out of service for critical applications after 90 to 150 such operations. Many organizations doing daily backups replace their tapes after 30, 60 or 90 days.
For Imation's suggestions on 4-mm tapes, see the article on their Web site at: www.imation.com/en_US/main.jhtml?Id=12_10_02&Article=2002_02_4mmtape.xml.
Rick Cook has been writing about mass storage since the days when the term meant an 80K floppy disk. The computers he learned on used ferrite cores and magnetic drums. For the last twenty years he has been a freelance writer specializing in storage and other computer issues.
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