Dedup and Zero Detect

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apol
Posts: 267
Joined: Wed May 07, 2014 1:51 am

Dedup and Zero Detect

Post by apol »

Hi,

is it ok and does it make any sense to enable both dedup and zero detect on the same volume? I thought that dedup is more or less a superset of zero detect and left zero detect off for dedup volumes, but apparently automatically created secondary volumes have both features enabled (both 3.2.2 and 3.3.1 do this).
When all else fails, read the instructions.
MammaGutt
Posts: 1578
Joined: Mon Sep 21, 2015 2:11 pm
Location: Europe

Re: Dedup and Zero Detect

Post by MammaGutt »

My understanding is that this is primarily which numbers you want to look good. Disable zero detect and the dedupe ratio will increase, enable zero detect and general compaction/thin ratio will increase.

Without zero detect, you will store a 16kB block with all zeros in th DDS, with zero detect on all volumes you don’t. To my knowledge no other AFAs support zero detect and will dedupe zero blocks to increase dedupe ratio and 3PAR does the same by default.
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i3laze
Posts: 4
Joined: Tue Nov 19, 2019 10:32 am

Re: Dedup and Zero Detect

Post by i3laze »

Just a small observation on latest firmwares:

Zero Detect option is always Enabled on newly created TTPVs.
Enabling Dedup superseeds Zero Detect and hides that advanced option.
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