08-06-04 10:45 PM
"Berry" <Berry@NOMAILSERVER.TLD> wrote in message
news:41139e39$0$144$e4fe514c@dreader17.news.xs4all.nl...
> I heard a story that when using a (S)DLT drive no VERIFY of the data is
> needed to have a succesful backup which you can trust.
>
> Is this true?
>
> Regards,
>
> Berry
Every modern tape drive (DLT, SLR, AIT, LTO, VXA) with more intelligence
than a Travan or QIC drive has on the fly read-after-write verify, if that's
what you mean. The drive writes data to tape, and reads it back immediately
with a separate set of heads. In theory this would eliminate the need for
verify. However, all it does is verify that the data is readable, and
compares to whatever was received by the drive buffer. The entire data path
in between from your disks through memory, through several device drivers
and through your SCSI/IDE/Fibre bus goes unchecked with read-after-write. So
do a verify if your data is worth anything..
Read-after-write verify is designed to deal with media defects, not to
replace your verify pass.
Rob
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