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From: cheeks@edsr.eds.com (Mark Costlow)
Newsgroups: comp.periphs.scsi,alt.sys.sun
Subject: Re: Exabyte News (High Speed Positioning)
Keywords: fast seek tape
Message-ID: <3291@tantalum.UUCP>
Date: 26 Oct 90 05:39:05 GMT
References: <1990Oct20.134852.2161@ecn.purdue.edu>
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In article <1990Oct20.134852.2161@ecn.purdue.edu>, ghg@ecn.purdue.edu (George Goble) writes:
|> 
|> New Exabyte drives will have the capability of hi speed positioning.
|> There currently exists an "EXB-8200-SX" which is an EXB-8200 with an
|> addtional chip to count servo tach pulses.
|> 

Just ordered one.  Sounds cool.


|> Although, not optimum for Unix, there may be hope in making use of
|> it for dump/restore.  As currently implemented, one must first use
|> a "showblock" scsi command, which returns a 10 byte quantity, to 
|> identify the current position on the tape.  As documented, one is
|> supposed to "leave a trail of crums" (do showblock's as the tape is
|> written) and save these indicies in a "directory" someplace.
|> 

Out of curiosity, what kind of performance hit does one take when doing
"showblock"s all the time while writing?  Does the drive continue to
stream, or does it have to stop and reposition?

|> 
|> Geo. Goble, Engr Comp Network, Purdue U.    pur-ee!ghg ghg@purdue.edu

Mark
-- 
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