Date: Mon, 16 Feb 1998 12:58:47 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Capriotti <capriotti@geocities.com> Cc: hackers@FreeBSD.ORG Subject: Re: SFT Message-ID: <XFMail.980216125847.shimon@simon-shapiro.org> In-Reply-To: <3.0.32.19691231210000.00a226f0@pop.mpc.com.br>
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On 14-Feb-98 Capriotti wrote:
> Hey, boys, just one question that crossed my mind:
>
> Why can't the kernel do something like:
>
>
> (consider a system w/ mirrowed disks using ccd)
>
> if (main disk) fails then start using (mirror disk)
>
> What - technically - prevents ccd/kernel/something else from being able
> to
> do it ?
>
> At 11:33 AM 1/6/98 -0800, you wrote:
>>
>>On Tue, 6 Jan 1998, Capriotti wrote:
>>
>>> Does anyone have any news about System Fault Tolerance under Free ?
>>>
>>> Like what Novell has, from mirrowed disks to mirrowed servers ?
>>
>> Mirrored disks can be done with ccd.
I am working on these issues. They are not as simple as one would have
liked them to be. My proposed solution will come in several flavours:
a. Fault Resilient; Where hardware failure does not destroy the data, and
common hardware problems can be survived without disruption of service.
b. High Availability; Where the system does not have a SPOF (single Point
Of Failure), and can detect failures, and swith over processing from a
failed component to a healthy component.
c. Fault Tolerant; Where a single failure will not discrupt the service,
which will be able to continue, in a manner transparent to external
users.
My plan is to have options a. & b. available before April 1998, and option
c. by year end. I am planning on directing much of this discussion (unless
told otherwise) to freebsd-database, as this is typically where the most
interested audience should be, and since many of the tools developed have
one thing or another to do with database technology.
----------
Sincerely Yours,
Simon Shapiro
Shimon@Simon-Shapiro.ORG Voice: 503.708.7858
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