Messages in this thread | | | From | "Stephen C. Tweedie" <> | Date | Mon, 26 Jul 1999 22:13:24 +0100 (BST) | Subject | Re: High-availability question |
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Hi,
On Sat, 24 Jul 1999 12:05:36 +0200, Ralf Baechle <ralf@uni-koblenz.de> said:
>> No. Then you'd have a single machine handle the filesystem >> and I don't want no single point of failure.
> You're searching for the silver bullet which doesn't exist. I know of > some Omirr like ha-system in a German bank. A pair of machines for > reasons of availability even distributed over a city each had mirrored > disks, running OpenVMS.
VMS host-based shadowing is _nice_. :)
> The data corruption caused by a not correctly plugged in SCSI cable > resulted in both mirror sets being corrupted and the corrupted data > also being mirrored over to the other system.
Sure --- garbage in, garbage out. You still aren't proof against an application failure or against writing the wrong data. That doesn't mean that having a redundant storage subsystem is useless: it just means that such redundancy is only part of the problem.
btw, Tandem would have caught that scsi error: the existence of such fault tolerant systems shows that it _is_ possible to guard against random machine failures. You are still in trouble if the application is buggy, of course.
--Stephen
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