[clug] Linux on mirrored disks using software raid 1

Burn Alting burn at goldweb.com.au
Mon Jul 7 12:25:32 EST 2003

On Mon, 2003-07-07 at 11:59, Martin Pool wrote:
> On  7 Jul 2003, Michael.James at csiro.au wrote:
> > Boots fine, works runs etc
> >  but when I pulled the power plug out of one drive
> >  the system went into a decline.
> > In 5 minutes it was catatonic.
> Whitebox hardware is not designed to allow you to unplug random
> components while it's running.  Who knows what transients doing so
> might introduce on the power or signal lines?  Be glad you did not fry
> your motherboard.  I have seen it happen from similar foolishness.
> IDE mirroring is mostly intended to protect against data loss caused
> by media failure.  You can safely simulate that by shutting the
> machine down, unplugging a drive, and rebooting it.
> If you want to have the machine not crash when a component
> electrically fails, you need to either buy genuine redundant hardware,
> or have a cluster of separated machines.

I'd also point out that, even with an addon PCI ATA card, unless it's
specifically designed, power cycling an IDE slave or master can leave
the chipset on the card in a very non-deterministic state! When I say
specifically designed, I'm talking about both the IDE driver AND MORE
IMPORTANTLY an adaptor between the cable and drive which 'simulates a
nice power down' from the IDE chip's perspective.

Perhaps your best bet would be a SATA solution which has hot-unplug
functionality catered for.

Burn Alting
burn at goldweb.com.au

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