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Date: Tue, 11 Sep 2007 16:20:15 -0500
From: Decibel! <decibel@decibel.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Greg Smith <gsmith@gregsmith.com>, pgsql-performance@postgresql.org
Subject: Re: DRBD and Postgres: how to improve the perfomance?
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On Mon, Sep 10, 2007 at 12:54:37AM -0400, Tom Lane wrote:
> Greg Smith <gsmith@gregsmith.com> writes:
> > On Sat, 8 Sep 2007, Joshua D. Drake wrote:
> >> You would have to have lightning handed by God to your server to have =
a=20
> >> total power failure without proper shutdown in the above scenario.
>=20
> > Do you live somewhere without thunderstorms?  This is a regular event i=
n=20
> > this part of the world during the summer.  It happened to me once this=
=20
> > year and once last; lost count for previous ones.  In both of the recen=
t=20
> > cases it's believed the servers were burned from the Ethernet side beca=
use=20
> > somewhere in the network was a poor switch that wasn't isolated well=20
> > enough from the grid when the building was hit.  Lightning is tricky th=
at=20
> > way; cable TV and satellite wiring are also weak links that way.
>=20
> Yeah.  I've lost half a dozen modems of varying generations, a server
> motherboard, a TiVo, a couple of VCRs, and miscellaneous other equipment
> from strikes near my house --- none closer than a couple blocks away.
> I don't really care to think about what would still work after a direct
> hit, despite the whole-house surge suppressor at the meter and the local
> suppressor on each circuit and the allegedly surge-proof UPSes powering
> all the valuable stuff.  I've also moved heavily into wireless local

<dons EE hat>
Pretty much every surge supressor out there is a POS... 99.9% of them
just wire a varistor across the line; like a $0.02 part is going to stop
a 10,00+ amp discharge.

The only use I have for those things is if they come with an equipment
guarantee, though I have to wonder how much those are still honored,
since as you mention it's very easy for equipment to be fried via other
means (ethernet, monitor, etc).

> net to eliminate any direct electrical connections between machines that
> are not on the same power circuit (the aforesaid burned motherboard
> taught me that particular lesson).  And yet I still fear every time a
> thunderstorm passes over.

Wired is safe as long as everything's on the same circuit. My house is
wired for ethernet with a single switch running what's going to every
room, but in each room I have a second switch on the same power as
whatever's in that room; so if there is a strike it's far more likely
that I'll lose switches and not hardware.

> Then of course there are the *other* risks, such as the place burning to
> the ground, or getting drowned by a break in the city reservoir that's
> a couple hundred yards up the hill (but at least I needn't worry about

Invest in sponges. Lots of them. :)
--=20
Decibel!, aka Jim Nasby                        decibel@decibel.org
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)

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