27MB/s is for HP drives, and HP employs the best overall data rate 
matching mechanism.
40MB/s for IBM drives, and it's not variable like HP.  The drive must 
literally switch gears resulting in speeds of 40, 50, 60, 70 or 80 MB/s
7.5MB/s for Seagate/Quantum/Certance but don't be decieved by their 
"13-speed" marketing.  The drive not only needs to switch gears, but it 
can only switch at the beginning or end of the tape, making shoeshining 
a very real possibility.

Again, I don't have references, so take me with a grain of salt ;)


----Originial message----
Date: Mon, 25 Sep 2006 18:17:34 -0600
From: "Scott Jacobson" <SJACOBSO at novell.com>
Subject: Re: [Veritas-bu] LTO3 show shining

Remember, variable speed matching supported on some manufactures tape 
drives doesn't necessarily make Justin's suggested performance speeds an 
absolute.  But his performance number's are a good base line.
-sj

>>> Justin Piszcz <jpiszcz at lucidpixels.com> 9/25/2006 3:20 PM >>>
If your speeds are < 27MB/s, you get "Shoe Shining" - 27MB/s is the
minimum you are supposed to run an LTO3 drive at.

Justin.

On Mon, 25 Sep 2006, Hindle, Greg wrote:

> Nb 5.0 mp6 Solaris 9
>
> Ok Maybe this has been said before but with all the talked about show
> shining LTO3 FC drives. Currently I have NDMP backups going to my LTO 3
> drives. Early next year when we buy more LTO3 drives we are changing
> over our non-ndmp backups to go to LTO3 drives as well.  My questions
> are this:
>
> What settings need to be changed and to what to minimize LTO3 show
> shining?
>
> How can I tell if my drives are show shining? Where do I look, what
> commands do I need to run etc.?


-- 
Joe Royer / SysAdmin / Digital Motorworks / 512-692-1028


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