From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Alex Stapleton <alexs(at)advfn(dot)com> |
Cc: | snacktime <snacktime(at)gmail(dot)com>, "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: Why database is corrupted after re-booting |
Date: | 2005-10-27 13:57:03 |
Message-ID: | 18408.1130421423@sss.pgh.pa.us |
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Lists: | pgsql-general |
Alex Stapleton <alexs(at)advfn(dot)com> writes:
> suspicion is that if the power failure isn't a particularly fast one,
> (e.g. you overloaded a fuse somewhere, fuses are insanely slow to
> fail compared to alternatives like MCBs) then your RAID card's RAM
> will get corrupted as the voltage drops or the system memory will
> resulting in bad data getting copied to the RAID controller as RAM
> seems to be pretty sensitive to voltage variations in experiments
> i've done on my insanely tweak-able desktop at home. I would of
> though ECC probably helps, but it can only correct so much.
Any competently designed battery-backup scheme has no problem with this.
What can seriously fry your equipment is a spike (ie, too much voltage
not too little). Most UPS-type equipment includes surge suppression
hardware that offers a pretty good defense against this, but if you get
a lightning strike directly where the power comes into your building,
you're going to be having a chat with your insurance agent. There is
nothing made that will withstand a point-blank strike.
regards, tom lane
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