[Users] deduplication

[suporte at logicworks.pt]

So, we can say that dedup has more disadvantages than advantages. 

And what about dedup of Netapp? 

Jose 

----- Original Message -----

From: "Karli Sjöberg" <Karli.Sjoberg at slu.se> 
To: suporte at logicworks.pt 
Cc: "Jiri Belka" <jbelka at redhat.com>, users at ovirt.org 
Sent: Quinta-feira, 30 de Maio de 2013 8:33:19 
Subject: Re: [Users] deduplication 

ons 2013-05-29 klockan 09:59 +0100 skrev suporte at logicworks.pt: 

Absolutely agree with you, planning is the best thing to do, but normally people want a plug'n'play system with all included, because there is not much time to think and planning, and there are many companies that know how to take advantage of this people characteristics. 
Any way, I think another solution for dedup is FreeNAS using ZFS. 



FreeNAS is just FreeBSD with a fancy web-ui ontop, so it´s neither more or less of ZFS than you would have otherwise, And regarding dedup in ZFS; Just don´t, it´s not worth it! It´s said that it may increase performance when you have a very suitable usecase, e.g. everything exactly the same over and over. What´s not said is that scrubbing and resilvering slows down to a snail (from hundreds of MB/s, or GB if your system is large enough, down to less than 10), just from dedup. Also deleting snapshots of datasets that have(or have had) dedup on can kill the entire system, and when I say kill, I mean really fubar. Been there, regretted that... Now, compression on the other hand, you get basically for free and gives decent savings, I highly recommend that. 

/Karli 


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Jose 




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<blockquote>
From: "Jiri Belka" <jbelka at redhat.com> 
To: suporte at logicworks.pt 
Cc: users at ovirt.org 
Sent: Quarta-feira, 29 de Maio de 2013 7:33:10 
Subject: Re: [Users] deduplication 

On Tue, 28 May 2013 14:29:05 +0100 (WEST) 
suporte at logicworks.pt wrote: 

> That's why I'm making this questions, to demystify some buzzwords around here. 
> But if you have a strong and good technology why not create buzzwords to get into as many people as possible? without trapped them. 
> Share a disk containing "static" data is a good idea, do you know from where I can start? 

Everything depends on your needs, design planning. Maybe then sharing 
disk would be better to share via NFS/iscsi. Of course if you have many 
VMs each of them is different you will fail. But if you have mostly 
homogeneous environment you can think about this approach. Sure you have 
to have plan for upgrading "base" "static" shared OS data, you have to 
have plan how to install additional software (different destination 
than /usr or /usr/local)... If you already have your own build host 
which builds for you OS packages and you have already your own plan for 
deployment, you have done first steps. If you depend on upgrading each 
machine separately from Internet, then first you should plan your 
environment, configuration management etc. 

Well, in many times people do not do any planning, they just think some 
good technology would save their "poor" design. 

j. 


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	-- 

Med Vänliga Hälsningar 
------------------------------------------------------------------------------- 
Karli Sjöberg 
Swedish University of Agricultural Sciences 
Box 7079 (Visiting Address Kronåsvägen 8) 
S-750 07 Uppsala, Sweden 
Phone: +46-(0)18-67 15 66 
karli.sjoberg at slu.se 
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