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From: Don Lewis <truckman@FreeBSD.org>
Subject: Re: IBM blade server abysmal disk write performances
To: wojtek@wojtek.tensor.gdynia.pl
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On 18 Jan, Wojciech Puchar wrote:

> If computer have UPS then write caching is fine. even if FreeBSD crash, 
> disk would write data

I've had my share of sudden UPS failures over the years.  Probably more
than half have been during an automatic battery self test.  UPS goes on
battery, and then *boom*, everything shuts down.  At that point the UPS
helpfully indicates that the battery needs to be replaced.  This seems
to happen more frequently once the batteries get to be about 4 years
old.  I've started replacing them after 3 years.

My next big build will have redundant PSUs, each connected to a separate
UPS.