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doc: add recommendations for managers
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Thomas Schoebel-Theuer
Thomas Schoebel-Theuer
parent
9f8061d529
commit
bd1cb9e8f6
@ -11604,7 +11604,7 @@ not
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\end_layout
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\begin_layout Section
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Recommendations for Designing and Operating Storage Systems
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Recommendations for Design and Operation of Storage Systems
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\begin_inset CommandInset label
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LatexCommand label
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name "sec:Recommendations-for-Designing"
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@ -11612,6 +11612,474 @@ name "sec:Recommendations-for-Designing"
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\end_inset
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\end_layout
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\begin_layout Subsection
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Recommendations for Managers
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\begin_inset CommandInset label
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LatexCommand label
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name "subsec:Recommendations-for-Managers"
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\end_inset
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\end_layout
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\begin_layout Standard
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When you are responsible for
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\series bold
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masses of enterprise-critical data
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\series default
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, the most important point is to get people with
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\series bold
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the right skills
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\series default
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, in
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\emph on
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addition(!) to
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\emph default
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the
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\emph on
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right mindset
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\emph default
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, and to assign the right roles to them.
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\end_layout
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\begin_layout Standard
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Practical observation from many groups in many companies: which storage
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systems / architectures are in use, and how much they are
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\emph on
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really
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\emph default
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failure resistent and reliable, and how much they are
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\emph on
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really
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\emph default
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scalable for their workload, and what is their TCO (Total Cost of Ownership),
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does often
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\emph on
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not
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\emph default
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depend on real knowledge and facts.
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It often depends on
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\series bold
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personal habits
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\series default
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and
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\series bold
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pre-judgement
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\series default
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of staff
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\begin_inset Foot
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status open
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\begin_layout Plain Layout
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\noindent
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This can be seen in a bigger company (e.g.
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after mergers etc) when very different architectures have been built by
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different teams for very similar usecases, although they are sometimes
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even roughly comparable in size and workload.
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\end_layout
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\end_inset
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.
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In essence, this results in a gambling game how safe / cost-effective etc
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your critical data
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\emph on
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really
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\emph default
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is.
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\end_layout
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\begin_layout Standard
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As just explained in the previous section, there are so many pitfalls, and
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there are only a few people who know them, because more people are working
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in small-scale systems than in large-scale enterprise ones.
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There are so many lots of people at the market who
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\emph on
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claim
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\emph default
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to have some experience, but in reality they don't know what they don't
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know (
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\series bold
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second-order ignorance
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\series default
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).
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\end_layout
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\begin_layout Standard
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Second-order ignorance is very dangerous, even for affected people themselves,
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because they are in good faith about their own skills, and that they would
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be able to control everything (sometimes they really want to control literally
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\emph on
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everything
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\emph default
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, even other people who have more real experience and knowledge).
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See for example wrong assumptions and
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\begin_inset Quotes eld
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\end_inset
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false proofs
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\begin_inset Quotes erd
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\end_inset
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about scalability, derived from different usecases (or in extreme cases
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even from workstations workloads), or the failed scalability scenario in
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section
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\begin_inset CommandInset ref
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LatexCommand vref
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reference "subsec:Example-Failures-of"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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where some freelancers were consulted as
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\begin_inset Quotes eld
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\end_inset
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external experts
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\begin_inset Quotes erd
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\end_inset
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.
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\end_layout
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\begin_layout Quotation
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\noindent
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\begin_inset Graphics
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filename images/MatieresCorrosives.png
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lyxscale 50
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scale 17
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\end_inset
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Check your information sources! There is a
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\emph on
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systematic reason
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\emph default
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for ill-informed
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\begin_inset Quotes eld
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\end_inset
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experts
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\begin_inset Quotes erd
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\end_inset
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.
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On the internet, you can find a lot of so-called
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\begin_inset Quotes eld
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\end_inset
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best practices
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\begin_inset Quotes erd
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\end_inset
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.
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Many of them propagating badly scaling storage architectures for enterprise
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workloads, sometimes even
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\emph on
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generally
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\emph default
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claiming they would
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\begin_inset Quotes eld
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\end_inset
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scale very well
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\begin_inset Quotes erd
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\end_inset
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, which is however often based on
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\emph on
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assumptions
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\emph default
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instead of knowledge (and almost never based on
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\emph on
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measurements
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\emph default
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at the right measurement points for deriving substantial knowledge about
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your real application behaviour).
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Literally
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\emph on
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anyone
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\emph default
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can post falsely generalized
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\begin_inset Quotes eld
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\end_inset
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best practices
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\begin_inset Quotes erd
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\end_inset
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to the internet.
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Together with second-order ignorance about the non-transferability of
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\begin_inset Quotes eld
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\end_inset
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success stories
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\begin_inset Quotes erd
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\end_inset
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from usecase A to usecase B (resulting in
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\emph on
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false
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\begin_inset Quotes eld
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\end_inset
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proofs
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\emph default
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\begin_inset Quotes erd
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\end_inset
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), the internet is creating
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\series bold
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information bubbles
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\series default
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.
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\end_layout
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\begin_layout Quotation
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\noindent
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\begin_inset Graphics
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filename images/lightbulb_brightlit_benj_.png
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lyxscale 12
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scale 7
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\end_inset
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Real knowledge originates from evaluated sources, such as
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\series bold
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scientific publications
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\series default
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which have undergone at least some minimum
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\emph on
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quality check
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\emph default
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, and which are trying to describe their preconditions and operating environment
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s as precisely
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\begin_inset Foot
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status open
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\begin_layout Plain Layout
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\noindent
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Therefore, chances are better to get a real expert when he has some (higher)
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academic degrees, and was working in the area for a longer time.
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\end_layout
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\end_inset
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as possible.
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\end_layout
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\begin_layout Quotation
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\noindent
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\begin_inset Graphics
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filename images/lightbulb_brightlit_benj_.png
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lyxscale 12
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scale 7
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\end_inset
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Real experts will tell you when they don't know something.
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In addition, they will tell you
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\emph on
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multiple
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\emph default
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ways for abtaining such information, such as measurements, simulation,
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etc.
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\end_layout
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\begin_layout Standard
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If you don't have anyone in your teams who knows how
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\series bold
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caching
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\series default
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\emph on
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really
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\emph default
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works, or if it is a single guy who cannot withstand the pressure from
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a whole group of
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\begin_inset Quotes eld
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\end_inset
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alpha animals
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\begin_inset Quotes erd
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\end_inset
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, you are running an
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\series bold
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increased risk
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\series default
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of unnecessary expenses
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\begin_inset Foot
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status open
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\begin_layout Plain Layout
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I know of cases which have produced unnecessary
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\emph on
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direct
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\emph default
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cost of at least € 20 millions.
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\end_layout
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\end_inset
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, worse services (indirect costs), failed projects, and sometimes even resulting
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in loss of market share and/or of stock exchange value.
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\end_layout
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\begin_layout Standard
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The problem is that it
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\emph on
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looks so easy
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\emph default
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, as if everyone could build a larger storage system, with ease.
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For example, just
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\begin_inset Quotes eld
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\end_inset
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spend some more money
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\begin_inset Quotes erd
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\end_inset
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, that's all you would need.
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Unfortunately, both
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\begin_inset Quotes eld
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\end_inset
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marketing drones
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\begin_inset Quotes erd
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\end_inset
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from commercial storage vendors, and even a few OpenSource advocates, are
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propagating this
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\series bold
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dangerous mindset
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\series default
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.
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\end_layout
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\begin_layout Standard
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As a responsible manager, how can you detect dangerous partly knowledge?
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Good indicators are wrong usage of the term
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\begin_inset Quotes eld
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\end_inset
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architecture
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\begin_inset Quotes erd
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\end_inset
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(see definition in section
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\begin_inset CommandInset ref
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LatexCommand vref
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reference "sec:What-is-Architecture"
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plural "false"
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caps "false"
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noprefix "false"
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\end_inset
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), and/or
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\series bold
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confusion of architecture with implementation
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\series default
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.
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When somebody confuses
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\begin_inset Foot
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status open
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\begin_layout Plain Layout
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Notice that there exist people who use the term
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\begin_inset Quotes eld
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\end_inset
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architecture
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\begin_inset Quotes erd
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\end_inset
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inadvertly.
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They even don't even know that they are confusing architecture with implementat
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ion.
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Pure usage of a certain term is no clear indicator that somebody is really
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an expert.
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\end_layout
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\end_inset
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this, he does not really have an overview of different architectural solution
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classes.
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Instead, such people are tending to propagate their random
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\begin_inset Quotes eld
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\end_inset
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favourite product
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\begin_inset Quotes erd
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\end_inset
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.
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For a responsible, this increases the risk of getting a non-optimum or
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even bad / dangerous solutions.
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\end_layout
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\begin_layout Standard
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Not everything which works in a garage, or in a student pool, or in the
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testlab (whether it's yours or from a commercial storage vendor), or in
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a PoC with some
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\begin_inset Quotes eld
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\end_inset
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friendly customers
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\begin_inset Quotes erd
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\end_inset
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, is well-suited for large enterprises and their critical data (measured
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in petabytes / billions of files / etc), or is the optimum solution for
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TCO.
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Some rules of thumb, out of experience and observation:
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\end_layout
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\begin_layout Itemize
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For each 1 or 2 orders of magnitude of the
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\series bold
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size
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\series default
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of your data, you need better methods for safe construction and operation.
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At least for each 3 to 4 orders of magnitude (sometimes even for less),
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you need
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\series bold
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better architectures
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\series default
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, and people who can deal with them.
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\end_layout
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\begin_layout Itemize
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For each 1 or 2 orders of magntitude of
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\series bold
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criticality
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\series default
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of your data (measured by
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\emph on
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losses
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\emph default
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in case of certain incidents), you will also need better architecture,
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not just better components.
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\end_layout
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\begin_layout Subsection
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Recommendations for Architects and Sysadmins
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\begin_inset CommandInset label
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LatexCommand label
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name "subsec:Recommendations-for-Architects"
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\end_inset
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\end_layout
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\begin_layout Standard
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