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From:Claudio Nanni Date:February 5 2009 4:26pm
Subject:Re: Instance scale-out
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First to help people join the discussion, the guilty paragraph of
certification study guide 42.1
--------------------------------------------------------------------------------------------------------------
  Each server must have its own network interfaces, including the TCP/IP
port, the named pipe or
  shared memory (on Windows), and the Unix socket file (on Unix). One server
cannot use
  network interfaces that are used by another server; it will not even start
up properly if it discovers
  that its network interfaces are already in use. Note that it isn't
necessary to set up multiple
  hostnames for the server host. All the MySQL servers running on a given
host can share the
  same hostname. They can also share the same IP address as long as they
listen on different
  TCP/IP port numbers.
--------------------------------------------------------------------------------------------------------------

Hey John,
I am really interested in this discussions, as you see!
I understand perfectly what is the meaning with the MySQL
certificator/certified glasses, but I am not really use to see a unit socket
file
as a network interface, not even the shared memory.
I understand that this is all about semantic but I guess there is 99% that
rather would call the 'mysql network interface' simply as a communication
channel, pipeline, or stack.
Named pipes, Shared Memory, Unix socket file have nothing to do with
network, they live on the same server,
and do not even need any network protocol.

[X] Named pipes and Shared Memory are means for windows channel for
interprocess communication
[X] Unix socket file is same thing on unix systems, using a file as pipe.

I am not confusing hardware and software, I do not care if and how many
physical cards are in the host,
for me the network interface is a layer of software that enable two or more
systems to communicate over
a network of interconnected systems, be the interconnection medium any,
ethernet, wireless, bluetooth, CDN,
The network card must be bridging the physical medium that transport
information with the host, so it can be
any piece of hardware, but the greatness of standards and protocols is
abstraction, and thank the Lord!
We have the internet accessible from almost everywhere! DSL, WI-FI, UMTS,
3G, also I tried TCP/IP over Bluetooth!
I just need from a O.S. level have available a network interface (see
virtual hosts, they can all be bound to the same physical card)

Would you please issue and comment the following commands?

$man ifconfig
$ifconfig eth0

I am positive that the book is using the words 'network interface' using a
meaning that is only in the mind of the authors, and a few more.


Claudio






2009/2/5 John Daisley <john.daisley@stripped>

> Claudio,
>
> Nobody is arguing, its a discussion list not an arguing list and this is a
> good discussion to have on here. Im very interested in seeing what others
> have to say about this but here is how I interpret it (based on my 18
> years of IT experience which includes many years working with MySQL
> including becoming mysql dba and dev certified amongst many other
> certifications)
>
> I would say in terms of the MySQL server the interface is either a TCP/IP
> Port, a Named Pipe, shared memory or a UNIX Socket. Depending on the host
> operating system it can use any of those interfaces but each instance must
> have its own interface.
>
> I believe you are confusing server hardware and server software. Do you
> consider a server to be a physical machine or an application that runs on
> a physical machine? Its the same difference. The network card is physical
> hardware, the port is not!
>
> John
>
> > John,
> > I don't want to argue too much on this but I'd also like the opinion of
> > the
> > big heads in MySQL
> >
> > I think there's no grey area here.
> > An interface is an interface and can be of any type and supporting any
> > protocol(TCP/IP on ethernet card, UDP idem. DSL on WAN card, PPP on POTS
> > modem)
> >
> > A port is related ONLY to the TCP/IP protocol(in this case)
> >
> > Moreover, are all the *nix systems wrong?
> >
> >
>
> ---------------------------------------------------------------------------------------------------
> > [clna@terramia ~]$ man ifconfig
> > IFCONFIG(8)                Linux Programmer's Manual
> > IFCONFIG(8)
> >
> > NAME
> >        ifconfig - configure a network interface
> >
> > SYNOPSIS
> >        ifconfig [interface]
> >        ifconfig interface [aftype] options | address ...
> >
>
> ----------------------------------------------------------------------------------------------------
> >
> > So, let's see what a 'network interface' is:
> >
>
> ----------------------------------------------------------------------------------------------------
> > [clna@terramia ~]$ /sbin/ifconfig eth0
> >
> > eth0      Link encap:Ethernet  HWaddr 00:1C:23:3F:CB:C0
> >           inet addr:10.xxx.xxx.xxx  Bcast:10.xxx.xxx.xxx
> > Mask:255.255.255.0
> >           inet6 addr: fe80::21c:23ff:fe3f:cbc0/64 Scope:Link
> >           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> >           RX packets:4057947 errors:0 dropped:0 overruns:0 frame:0
> >           TX packets:3932495 errors:0 dropped:0 overruns:0 carrier:0
> >           collisions:0 txqueuelen:1000
> >           RX bytes:851379513 (811.9 MiB)  TX bytes:1896970616 (1.7 GiB)
> >           Interrupt:177
> >
>
> ----------------------------------------------------------------------------------------------------
> > Aren't we supposed to see just a port number here?
> >
> > Cheers
> > Claudio
> >
> >
> > 2009/2/5 John Daisley <john.daisley@stripped>
> >
> >> An interface by definition is a point of interconnection.
> >>
> >> Maybe its a bit of a grey area where the interpretation can be different
> >> depending on whether you think in terms of hardware or software.
> >>
> >> Its the port which is used to communicate with the MySQL (or indeed any
> >> other) server software so therefore for the server software (but maybe
> >> not
> >> the physical hardware) its the port which is the point of
> >> interconnection
> >> (the network interface).
> >>
> >> For me the book is correct but I can see where confusion could occur.
> >>
> >> John
> >>
> >> > Hi Claudio,
> >> >
> >> >    I don't think its your English, I agree with you that its not just
> >> > confusing it is wrong.
> >> >
> >> > "Each server must have its own network interface"
> >> >
> >> > At least for my 10 years experience in IT and UNIX I would understand
> >> > network interface as physical network interface unless specified as
> >> > otherwise. Maybe the MySQL community has a differenet opinion :P
> >> >
> >> >
> >> >
> >> > ;)
> >> >
> >> > cheers Andy.
> >> >
> >> > ----------------------------------------------------------------
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> >>
> >>
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Thread
Instance scale-outClaudio Nanni5 Feb
  • Re: Instance scale-outJohn Daisley5 Feb
  • Re: Instance scale-outAndy Smith5 Feb
    • Re: Instance scale-outJohn Daisley5 Feb
      • Re: Instance scale-outClaudio Nanni5 Feb
        • Re: Instance scale-outJohn Daisley5 Feb
          • Re: Instance scale-outAndy Smith5 Feb
            • Re: Instance scale-outJohn Daisley5 Feb
          • Re: Instance scale-outClaudio Nanni5 Feb
            • Re: Instance scale-outBaron Schwartz5 Feb
Re: Instance scale-outClaudio Nanni5 Feb