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<div class="moz-cite-prefix">Hi John,<br>
<br>
Le 30/04/2013 18:13, John Griffith a écrit :<br>
</div>
<blockquote
cite="mid:CA+qL3LVsrFCZPQJNCcoAfv6eFxUVt-44NY-2zxq-Ro2Oevd-0g@mail.gmail.com"
type="cite">
<div class="gmail_extra">Hi Sylvain,</div>
<div class="gmail_extra"><br>
</div>
<div class="gmail_extra" style="">This doc is a bit outdated and
references Nova Volumes etc, however the problem I think you're
having is that it makes some assumptions regarding knowledge of
how all the components tie together and what they do. They're
simply guidelines for possible configurations, however given the
flexibility of OpenStack and the numerous use cases I've always
thought this was sort of a difficult task (recommended hardware
configs).</div>
<div class="gmail_extra" style=""><br>
</div>
<div class="gmail_extra" style="">That being said, the Volume
Group and disk portion of that doc that's being discussed is in
relation to your block-storage through Cinder. This is the
back-end storage that you're configuring Cinder to use. The
preference regarding RAID, Size etc are completely up to you,
but you can make some of those decisions based upon how you
intend to use your OpenStack deployment.</div>
<div class="gmail_extra" style=""><br>
</div>
<div class="gmail_extra" style="">For example you can just take
any free disks/partitions on your Cinder node, create one big
LVM VG out of them (cinder-volumes) and the default Cinder set
up would then allocate space from this VG any time you do a
"cinder create". The recommendations in the doc are geared
toward what would typically be required to have a functional
setup, the size, configuration and type of disks you use is
going to vary depending upon how many tenants you plan to have,
how much block storage you suspect they'll deploy and what kind
of performance they're going to require.</div>
<div class="gmail_extra" style=""><br>
</div>
<div class="gmail_extra" style="">The other thing to keep in mind
is OpenStack is fully scale-out, so you can start with something
and as you need more storage for Cinder you can add Cinder nodes
with more disks/VG's.</div>
<div class="gmail_extra" style=""><br>
</div>
<div class="gmail_extra" style="">I hope that helps.</div>
<div class="gmail_extra" style=""><br>
</div>
<div class="gmail_extra" style="">John</div>
</blockquote>
<br>
<br>
I do agree with your point of view : it's up to the operator to
define which Cinder backend to use, physical setup, partitioning
etc.<br>
<br>
My point was not to know which one is better, rather to say "hey, we
tell people to use <i><b>two</b></i> SATA Disks, this is pretty
specific, so we should explain why".<br>
<br>
If there is no clear reason to recommend 2 disks without being clear
on how to use them, then the 2nd recommended disk is useless.<br>
<br>
Anyway, I'm not fond of giving people <i>recommended hardware</i>,
I would rather give people <i>recommended backends</i>, as of
course hardware is strongly depending on the backend itself.<br>
<br>
My 2 cents,<br>
-Sylvain<br>
<br>
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