SDLT Media Warranty

[Yonghee]

Hello,

I found document of SDLT Media Warranty at below web site.
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?locale=en_US&taskId=120&prodSeriesId=214836&prodTypeId=12169&objectID=lpg50360

There is a definition of normal working life of SDLT.
“For warranty purposes, "normal working life" for SDLT equates to one million passes or 260 full back ups (whichever is soonest). For warranty purposes, "normal working life" for SDLT equates to one million passes or 260 full back ups (whichever is soonest).”
I need to know that detail meaning of “one million passes”
What is the definition of passes?

[Mahesh Kumar Malik]

Hi Yonghee

A pass refers to a single movement of a section of the tape media across the head assembly. The number of passes may be determined by the number of times the cartridge is read or written "end to end". But, a more significant source of passes is the internal repositioning of the media when an application does not "stream" the drive. During streaming, the drive continually puts information onto the media. The data comes from the host quickly and steadily enough so that the drive does not stop the tape movement to wait for more data. When the drive does have to stop, it repositions the head to the last block written to the media by moving the tape backwards. Then, when the data arrives, the media is moved again across the head for recording. This repositioning passes the media back and forth across the head and so increases the number of tape passes for that section. Though SDLT tape cartridges are specified at 1,000,000 passes, currently there is no suggested number of passes after which a cartridge should be retired. In laboratory tests, the media has been usable even after very high numbers of passes and the media actually seems to improve with use. After 500,000 passes the tape should continue to function normally, unless it is being used in an environment with heat, humidity or contamination levels beyond those recommended.

Regards
Mahesh