Hi Dave!
Thank you very much for your reply!
I deleted some data this morning and waited for 4 hours before making a new
backup, but that doesn't seem to be enough. Is there any way to influence this
waiting period? A certain table reorg or stop/start of the server or is it just
hard-coded?
Thanks again for your help!
Kind regards,
Eric van Loon
Air France/KLM Storage Engineering
-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Del Hoobler
Sent: maandag 10 april 2017 18:12
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Deduplication
Hi Eric,
A few things:
- Client-side provides better overall throughput for Spectrum Protect because
the deduplication is spread across more CPU's. So if you can afford to do the
deduplication client-side, that is the best overall result.
- Client-side helps reduce network traffic
- The algorithms on how deduplication is performed are the same between client
and server.
The behavior you are seeing has to do with the reusedelay impact on
deduplicated chunks. If the reusedelay is 1 day (default), that means
Spectrum Protect keeps the deduplicated chunks pinned in storage until
that time has passed. If the reusedelay is 0, there is a still a small
cushion window that might allow the chunks to still be linked to. If you
waited for a couple of hours AFTER the deletion occurred, I would not
expect those chunks to be reused.
Del
----------------------------------------------------
"ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU> wrote on 04/10/2017
10:57:27 AM:
> From: "Loon, Eric van (ITOPT3) - KLM" <Eric-van.Loon AT KLM DOT COM>
> To: ADSM-L AT VM.MARIST DOT EDU
> Date: 04/10/2017 11:01 AM
> Subject: Deduplication
> Sent by: "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>
>
> Hi guys!
> We are trying to make a fair comparison between server- and client-
> side deduplication. I'm running into an 'issue' where I notice that
> once you created a backup of a certain set of data, it is always
> deduplicated 100% afterwards when you start a new client-side
> deduped backup. Even when you delete all previous backup on the server
first!
> So I backed up a directory, retrieved all objectids through a select
> * from backups and deleted all objects, but still a new backup is
> deduplicated 100%. I don't understand why. I though it maybe had
> something to do with data still being in the container pool, but
> even with reusdelay=0, everything is deduplicated...
> Thanks for any help (Andy? :)) in advance.
> Kind regards,
> Eric van Loon
> Air France/KLM Storage Engineering
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