To prevent data loss, backups are made and data is archived. These are ZIP or RAR files under Windows, Linux archives like „.tar.gz“ and „.bz2“ archive files from image programs like „Acronis True Image“. But backups are error-prone too, sometimes already during the backup process, so data gets lost or defective.
This is a special backup method, where a tape drive is simulated by a server and the data is saved on a hard drive array. They are less prone to wear than tapes and provide a higher read and write speed.
With CD, DVD and BluRay backups errors often occur during the writing process or after a session was not finshed correctly.
Additonal errors occur if the CDs, DVDs or BluRays are rewritable, because they are easily being deleted or reinitialised.
It often happens that the so-called end marker isn't written correctly or the tape itself is reinitialised. On tape drives regularly used for backups, maladjustment of the read/write heads is common. This doesn't necessarily cause problems, but the tapes can't be reread in a new tape drive.