Date: Mon, 09 Mar 1998 09:49:07 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: (marino.ladavac@siemens.at) <lada@ws2301.gud.siemens.at> Cc: dmlb@ragnet.demon.co.uk, wilko@yedi.iaf.nl, julian@whistle.com, hackers@FreeBSD.ORG, lada@ws2301.gud.siemens.co.at Subject: Re: SCSI Bus redundancy... Message-ID: <XFMail.980309094907.shimon@simon-shapiro.org> In-Reply-To: <199803090845.JAA02668@ws6423.gud.siemens.at>
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On 09-Mar-98 marino.ladavac@siemens.at wrote:
> OLTP does not exists in Austria (i.e. not over Internet). The secure
> browsers
> are not available (see ITAR). The other issue is that the power
> availability
> seems much better here than in the USA--in the last 5 years I have had no
> power failures outside one planned (and known two months in advance).
> This,
> of course has a bearing on the measures taken to live through the
> failures,
> at least for ISP's.
OLTP, at least what I mean by OLTP, is a concept/transaction type; On-Line
Transaction Processing. As Such it exists in Australia. Has nothing to do
with the Internet. You could view e-mail as OLTP, as the transactions are
started and committed on-line, with the rewuester connected from initiating
the transaction through validation of acceptance or notification of
rejection.
The reliability of a service or subsystem has no bearing on wanting to
protect from its loss. Only the damage if you do not protect from its loss;
Itmatters not how reliable your disks are, only how expensive (money or
otherwise) is the loss of a disk. If the damage is ignorable, then RAID is
unnecessary, if cost is high, RAID-{1,5} may be appropriate. If the cost
is critical, even RAID by itself may not be enough.
What I am trying to acomplish in this conversation, is that the range of
services and their sensitivity to interruption is wide. FreeBSD is
migrating from a hacker's desktop to a high caliber server. Some services
and features need to acompany this migration, or it will fail.
All O/Ss going into the service market are going through this perocess. M$
Nice Try is already going there.
...
All this discussion about diesels is fascinating but;
a. Most ISPs cannot afford such a system, unless they colocate within a
much larger facility that can.
b. Battery backup systems can live for minutes. If power needs extend
into hours, mecahnical means of generating electrivity are needed.
c. Up to 10KW, gasoline generators are fine.
d. Above 10KW, and below 1MW, Diesel engines provide good service.
e. If you really want your power needs satisfied correctly, consult a
reputable power systems design house. There are too many variables to
cover in a mailing list dedicated to one particular software system.
Simon
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