RE: 64 node Oracle RAC Cluster (The reality of...)
- From: "Kevin Closson" <kevinc@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 21 Jun 2005 21:24:17 -0700
Mladen,
Please side-bar with me. I'll cover your questions.
I don't want to get spanked for spam if this thread
grows tiring to others...
I'll answer your questions under separate cover,
but the short answer is DLM and lock caching. Remember
that the processing which is causing concern for you
(fork,exec/map text and demand paging) is base
functionality for a filesystem....and as I stated
in my last post, unless a given technology can
perform basic FS func, don't call it an FS at
all, more less a CFS.
Heaven's sake, we'd never call /etc/passwd
a database now, would we? :-)
>-----Original Message-----
>From: oracle-l-bounce@xxxxxxxxxxxxx
>[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Mladen Gogala
>Sent: Tuesday, June 21, 2005 9:17 PM
>To: Kevin Closson
>Cc: Mladen Gogala; peter.sharman@xxxxxxxxxx;
>kevinc@xxxxxxxxxxxxx; mwf@xxxxxxxx;
>Rich.Jesse@xxxxxxxxxxxxxxxxx; oracle-l@xxxxxxxxxxxxx; Peter
>Ross Sharman
>Subject: Re: 64 node Oracle RAC Cluster (The reality of...)
>
>
>On 06/21/2005 11:53:35 PM, Kevin Closson wrote:
>
>> this is not true for a real CFS. A proxy-cfs or nfs exhibits the
>> characteristics you fear, but not a fully symmetric, concurrent
>> read:write CFS. Demand paging is nothing more than the internals of
>> mmap which in turn is really nothing more than an IO.
>> Oh, with one exception, it is entirely 100% read only (a major text
>> fault that is). That concern is a red herring. Binaries
>execute just
>> fine from a CFS.
>
>
>Kevin, I heard your name before and I am fully aware that you
>know much more then me. Truly symmetric clustered FS that I
>used to work with was known as Files-11. DEC representative
>used to tell us, I quote, "not to do image activation from
>remote nodes". As you probably know, VMS did not do file
>caching before version 6. The only question I have is
>synchronization of caches across the nodes.
>How can you achieve speed similar to the local FS? OS
>utilities usually do not support direct I/O. Oracle released a
>plug-in replacement for Linux utilities, so that you have ftp,
>cp, dd, ls, tar and cpio being able to utilize direct I/O. The
>thing still doesn't work for scp and sftp. So, how do you get
>around synchronizing caches on different nodes? I assume that
>there is a concept similar to SCN which gets increased with
>each transaction and if local SCN is higher then the global
>one, then you know that there was a change on your side and
>send all buffers with the increased SCN to the other guy or
>write the blocks down to the disk and have the other nodes
>re-read them (OPS technique). It still looks like a
>significant overhead which would slow down normal file
>operations significantly and make things like "vi
>$ORACLE_HOME/network/admin/listener.ora" fairly expensive.
>That would also interfere with the database operation and
>compete for the same bandwidth, wouldn't it?
>--
>Mladen Gogala
>Oracle DBA
>
>
>--
>//www.freelists.org/webpage/oracle-l
>
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