I usually strive to verify by direct observation or independent reliable
source, performance figures and other dubious claims made by any
manufacturer.  In this case, I was pleasantly reassured that the claim
is justified based on my personal observation.

Neil Strand

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Richard Sims
Sent: Friday, September 14, 2007 11:06 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] LTO4 and encryption questions

On Sep 14, 2007, at 10:44 AM, Strand, Neil B. wrote:

> I have observed almost no performance degradition using encryption.

The TS1120 redbook agrees:
"Enabling encryption incurs a less than 1% performance impact."
where the added time is to get the keys at load time.

But I think that's in ongoing operation.  From a reseller presentation,
their knowledgeable technician cited a 25 second extra time when the
tape is re-used as scratch (written from load point), in that it has to
write encryption information at the front AND position about 1/3 of the
way into the tape to additionally write the same information there, as
insurance in case the leading portion of the tape is mangled in one of
the drive problems we know so well.

    Richard Sims    http://people.bu.edu/rbs/ADSM.QuickFacts

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