Mailinglist Archive: opensuse (1470 mails)

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Re: [opensuse] experiences with bache / logic of caching
  • From: Per Jessen <per@xxxxxxxxxxxx>
  • Date: Wed, 17 Feb 2016 12:46:42 +0100
  • Message-id: <na1mj3$o45$1@saturn.local.net>
Anton Aylward wrote:

The battery could maintain the cache contents for 7 days during
a hardware fault / power outage. They had the battery connected to the
system via a Y-connector. The y-connector was accessible with the
system operational. Thus if the battery died due to old age, you
connected up the new battery before you disconnected the old, ensuring
you didn't have a window of vulnerability during the battery
replacement.

Sounds very much like Compaq Storageworks HSG80 controllers and associated
write-cache batteries.

That's a good mechanism. Was there something that noticed f the batter
died of old age? Was there a means for testing that mechanisms worked
(How far do you want to regress this?)

Did the mechanism nag, nag, nag endlessly?

LSI / 3ware cards require regular testing of the batteries. HP Smart Arrays
will alert you when the batteries have insuficcient capacity, I presume they
do their own internal testing.
When the capacity is insufficient, the write cache is disabled.

'Cos I'm sure I'm not alone when I speak of a set-up like this that the
sysop decided to turn off the alarm, and turn off the alarm .. and
um-plug the annoying alarm ... and forgot about it.

Perhaps, but disabling the write cache will have a noticable effect.


/Per

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