First, you can't compare the cost of disk and tape directly like that.
You have to include the drives and robots.  A drive by itself is useful;
a tape by itself is not.  

Setting that aside, if I put that disk in a system that's doing 20:1
de-duplication, my cost is now 1.65c/GB vs your 3-9c/GB.  

---
W. Curtis Preston
Backup Blog @ www.backupcentral.com
VP Data Protection, GlassHouse Technologies 

-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of Justin
Piszcz
Sent: Friday, September 21, 2007 7:36 AM
To: Jeff Lightner
Cc: veritas-bu AT mailman.eng.auburn DOT edu
Subject: Re: [Veritas-bu] Tapeless backup environments?


I believe disks are 33c/gigabyte and tapes are 3-9cents/gigabyte or even

cheaper, I do not remember the exact figures, but someone I know has
done 
a cost analysis and tapes were by far cheaper.  Also something that
nobody 
calculates is the cost of power to keep disks spinning.

Justin.

On Fri, 21 Sep 2007, Jeff Lightner wrote:

> Disk is not cheaper?  You've done a cost analysis?
>
> Not saying you're wrong and I haven't done an analysis but I'd be
> surprised if disks didn't actually work out to be cheaper over time:
>
> 1) Tapes age/break - We buy on average several hundred tapes a year -
> support on a disk array for failing disks may or may not be more
> expensive.
>
> 2) Transport/storage - We have to pay for offsite storage and transfer
-
> it seems just putting an array in offsite facility would eliminate the
> need for transportation (in trucks) cost.  Of course there would be
cost
> in the data transfer disk to disk but since everyone seems to have
> connectivity over the internet it might be possible to do this using a
> B2B link rather than via dedicated circuits.
>
> 3) Labor cost in dealing with mechanical failures of robots.   This
one
> is hidden in salary but every time I have to work on a robot it means
I
> can't be working on something else.   While disk drives fail it
doesn't
> seem to happen nearly as often as having to fish a tape out of a drive
> or the tape drive itself having failed.
>
>
> -----Original Message-----
> From: Justin Piszcz [mailto:jpiszcz AT lucidpixels DOT com]
> Sent: Friday, September 21, 2007 10:08 AM
> To: Jeff Lightner
> Cc: veritas-bu AT mailman.eng.auburn DOT edu
> Subject: Re: [Veritas-bu] Tapeless backup environments?
>
>
>
> On Fri, 21 Sep 2007, Jeff Lightner wrote:
>
>> Yesterday our director said that he doesn't intend to ever upgrade
>> existing STK L700 because eventually we'll go tapeless as that is
what
>> the industry is doing.   The idea being we'd have our disk backup
>> devices here (e.g. Data Domain) and transfer to offsite storage to
>> another disk device so as to eliminate the need for ever transporting
>> tapes.
>>
>> It made me wonder if anyone was actually doing the above already or
> was
>> planning to do so?
>>
>
> That seems to be the way people are 'thinking' but the bottom line is
> disk
> still is not cheaper than LTO-3 tape and there are a lot of advantages
> to
> tape; however, convicing management of this is an uphill battle.
>
> Justin.
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