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Date: Tue, 9 Mar 2010 13:35:08 -0700
Message-ID: <dcc563d11003091235u23423b38if274b3220d13dff7@mail.gmail.com>
Subject: Re: linux standard layout
From: Scott Marlowe <scott.marlowe@gmail.com>
To: Jan-Ivar Mellingen <jan-ivar.mellingen@alreg.no>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-admin@postgresql.org
Content-Type: text/plain; charset=ISO-8859-1

On Tue, Mar 9, 2010 at 1:18 PM, Jan-Ivar Mellingen
<jan-ivar.mellingen@alreg.no> wrote:
> Regarding 'pulling the plug' on the servers: Physical or virtual, always use
> a UPS. You can pull the plug as much as you like. When the power is about to
> run out it signals the server, which shuts down cleanly.
> Our servers have dual powersupplies, connected to separate UPS'es on
> separate power sources...

I've watched three redundant UPSes, three redundant power
conditioners, and the switch for the diesel generator all fry when the
perfect storm of events happened in a job 7 or 8 years ago.  Every
single machine in the hosting center lost power.   Of the hundred or
so database servers, mine was the only one that came up.  The others
all had to rely on off site backups to get up and running.  Not one
other DBA at that company had performed a power failure test.

> In a nutshell, I am heartly recommending virtualization.

In a nutshell, you are relying on luck that both heavy iron machines
can't lose power at the same time.  Sure, it's a low possibility, but
it's still a real one.

> And - I do not want to start a discussion about it. Just sharing my opinion.

Well, you can't throw the post you threw out there and not expect it
to start a discussion really.  I understand a lot of the reasoning for
virtualization.   My DB servers run at 75 to 100% capacity during
midday, there'd be no real advantage to buying an eve bigger piece of
iron to run them on.

I see the advantages of virtualization for certain load types, and
allowing to easily move services as a single disk image instead of
installing the service and configuring it on a new machine.  Where I
work all the servers (except the nagios box) work hard and there'd be
no real advantage to me in putting all my eggs in the virtualization
basket there.  I do use KVM to run multiple servers on my laptop for
testing.  It's great for that.  But hope is not a method I use when
installing my servers.