I agree about client encryption wrecking dedup ratios.

FWIW however, if you turn on both COMPRESSION and ENCRYPTION on the client,
the client is also smart enough to compress first, then encrypt, so you get
the compression benefits.

However, that of course takes a lot of cycles on the client, and can really
slow down restores.  Outboard compression/encryption in the hardware is
definitely superior.


On 1/23/08, Roger Deschner <rogerd AT uic DOT edu> wrote:
>
> Encryption might have a DRAMATIC effect, completely eliminating the
> benefits of either deduplication or compression. I predict 1:1. i.e. NO
> savings for dedupliaction, with TSM client encryption.
>
> This is why encryption at the tape drive is a very popular option with
> LTO4. You can both encrypt and compress at the same time.
>
> Roger Deschner      University of Illinois at Chicago     rogerd AT uic DOT 
> edu
>               Academic Computing & Communications Center
>
>
> On Wed, 23 Jan 2008, Ben Bullock wrote:
>
> > As with all questions like this, the answer is "it depends".
> > It depends on the make-up of your data (# of DB full dumps, % of DB
> >dumps to filesystem data, % of change on the client, etc)
> >It depends on the vendor of DeDupe you are using.
> >
> >FWIW, I am about to replace a 100TB of LTO tape with a DataDomain 560
> >dedupe box starting next week. Once the migration from tape to disk is
> >complete, I will be reporting what I saw in my environment. The DD folks
> >are saying that the worst case scenario will be a 7X reduction (i.e.
> >70TB of data squeezed into a 10TB DataDomain appliance). We shall see.
> >
> >Ben
> >
> >
> >-----Original Message-----
> >From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf 
> >Of
> >lamont
> >Sent: Wednesday, January 23, 2008 1:29 AM
> >To: ADSM-L AT VM.MARIST DOT EDU
> >Subject: [ADSM-L] Data Deduplication
> >
> >Hi,
> >What would likely be the de-dupe ratio if tsm clients do archive
> >processing daily (file level, no tdps) with encryption enabled?
> >
> >Thanks.
> >
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