Networker

Re: [Networker] Query in Staging from adv_file

2008-08-22 13:39:01
Subject: Re: [Networker] Query in Staging from adv_file
From: Curtis Preston <cpreston AT GLASSHOUSE DOT COM>
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Date: Fri, 22 Aug 2008 13:34:36 -0400
>Very interesting discussions.  However, I have some direct
>comments/questions for Curtis here:

>-> How do you deal with sites like mine, who have 'DBO Option Tier 5'
(aka
>Unlimited adv_file) and actually use it as our primary storage?  With
VTLs
>now licensed by size, I don't see EMC (or in our case Sun) 'trading in'

>one license for another while still keeping us happy - do they have an
>equiv 'Unlimited VTL' license?

I think that's a business relationship thing.  My conversation would go
something like, "We bought this because that wasn't available. Now
you're selling that."

>And its nice to be able to just 'drop in' disk for a project or a
>specialized SN - its now just plain cheaper than looking at VTL for the
>near future; Just buy a x4500 and a $2K SN license, or use an existing
>x4100, $2K SN, and some older DAS disk (Sun 3000 series SATA) using ZFS
>raidz2.

If you had the right VTL, you could do the same.  Some VTLs are easier
to add disk to than others.

>-> What is the point of de-dupe when more than half your data coming in
is
>pre-compressed, and is just likely to increase (especially when pre
>compressing gets you 2-5x more data per tape than the average tape
drive
>can do in real-time)?

Dedupe and compression are completely different beasts.  Compression
does not remove duplicate data over time.  It only eliminates redundant
data in each file.  Dedupe finds redundant data over time, such as data
redundant between two different full backups.

Precomopressing your data will have one of two effects on your dedupe
device, though, depending on which dedupe device we're talking about.
The first is that you might get no dedupe at all.  Some (many) do not
look or can't find redundancies in compressed data.  That would be
something for an RFI or testing.  The second is that it will cut the
dedupe ratio in half, since dedupe devices compress after they dedupe.






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