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Message Posted: Wed, 30 Jul 2003 @ 19:43:51 GMT

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This may not be your problem, but we have run into a similar issue with local attached DTL7000 drives. Performance degraded drastically when new media volumes were introduced to the silo. Since inception of the silo, it only contained the media volumes from "Company A".

At a certain point, new media volumes from "Company B" were introduced to the silo. This on occasion (more often than not), caused severe performance degradation when the new media "Company B" was used (normal 8 MB/sec down to about 1 MB/sec).

After researching the issue we found the drives can experience what is termed "Media Bias" when exposed to a single brand of tapes. If a single type media has been used on a device from when the device was new, it may experience a 'head wear issue'. This is when the head(s) of a drive get accustomed to a single type/style of media. When you introduce a new media to an older device/head, it has to check for errors constantly, thus impacting the performance of the back-up process drastically. The drive may also prompt for cleaning more frequently, even with new media.

We removed all the "Company B" media and reinserted new "Company A" media volumes back into the silo. We have had no problems since. We were also told that newer drive firmware can take care of the issue 80% of the time.

Kyle Prescott
Teradata Certified Professional
UnumProvident - Data Strategies, 3-South

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