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Re: Oracle Parallel Server

From: Pete Sharman <>
Date: 11 Jul 2002 13:21:19 -0700
Message-ID: <>

In article <>, Pete says...
>In article <agk0mn$pqn$>, "Jay" says...
>>What are the advantages of a clustered file system over raw devices? I
>>haven't had the opportunity to work with either.
>>I've been looking around the web for explanations/descriptions of clustered
>>file system but can't find anything good. It seems veritas makes one. But
>>is it a piece of software, hardware, or both. You mention compaq makes one
>>Is setting up and administering a RAC significantly harder than a single
>>instance database.
>>I think I'm struggling because I don't understand the pieces and how they
>>fit together. Would someone care to describe how the whole thing is put
>Dang, that's asking a bit much! ;)
>THe best thing I can suggest is to read the RAC Concepts manual. The RAC/OPS
>documentation has been the best written part of the doc (IMHO) in the last
>couple of releases.
>The difference between RAC on hardware that supports clustered file systems
>(CFS) and hardware that doesn't is relatively simple, but only applies to Unix
>environments and Win2K (i.e. not a concern on VMS). Unix cannot share files
>unless they're placed on raw devices. Since OPS and RAC both have a shared disk
>architecture, that means that the database files used to have to be on raw
>devices. Some people have issues with that, finding them harder to manage. I
>don't believe that's true, though. Others think raw devices are great for
>performance. They may be, but it's not a hard and fast fact. I remember an
>otherwise intelligent DBA telling me that raw devices ALWAYS improved
>performance by 30%. I couldn't convince him otherwise, so I let him go on his
>unenlightened way. Yes you can improve performance, yes it can be by 30% but no
>it's not ALWAYS that way.

Oh and one more I forgot - OS/390 works as well, and doesn't have the lag time you see with VMS releases.

>Back to CFS. When you install RAC, here's what happens. If your cluster is
>configured properly (i.e. the cluster software is working), the installer
>automatically picks up that it's running on a cluster and asks what nodes (other
>than the local one) you want to install RAC on. You can choose one or all of
>the available nodes. If you are using a CFS, then the kernel can be installed
>there and that's it. If you're not, the kernel installs once locally, and then
>behind the scenes does an rcp to install on every other node you've chosen.
>So in summary what a CFS gives you is two things:
>1. A simpler install - the rcp can fail if the oracle account logins are
>different on each node (don't laugh, I've seen it!)
>2. The ability to put your database files on the CFS (for Compaq anyway), where
>they can easily be seen and hopefully there's less chance of a dumb SYSADMIN
>mounting a raw device that had your database files on it (EOD - end of
>If you're running on 9.2, then Oracle can provide its own CFS. I think this
>applies for Windows only though (and maybe Linux).
>>"Pete Sharman" <> wrote in message
>>> In article <agijfd$j3j$>, "Jay says...
>>> >
>>> >Hi,
>>> >
>>> >My client may want to implement parallel server. They are (sorta) an HP
>>> >shop. But Oracle has been promoting RACs on Linux as a very cost
>>> >solution. Anyone ever implement upon Linux, Pros/Cons? Other platforms
>>> >Pros/Cons?
>>> >
>>> >Thanks
>>> >Jay
>>> >
>>> >
>>> And so it is. One of the real benefits of the Linux configs is that there
>>> certified configurations that you can use "out of the box". Depending on
>>> vendor you buy them from, you can either plug in the cluster and RAC is
>>> preloaded, or part of the purchase cost may include the time of a
>>> (not necessarily an Oracle one) to install and configure RAC. About the
>>> con I can think of is that Linux hasn't had the long history of supporting
>>> clustering in the way some other Unix platforms have.
>>> If you need to install everything yourself, then I think Compaq is a good
>>> (note this is purely a personal thing, not an Oracle recommendation)
>>because it
>>> has a clustered file system. Sun does too, but it's not supported for the
>>> database files (performance isn't good enough), and I know other vendors
>>> been working on them for a while, but remember Compaq bought Digital which
>>> course had clusters centuries ago (in computing time anyway). It will be
>>> interesting to see how HP uses the Compaq/Digital technology in this area.
>>> Having said that, I haven't really heard anything against any of the other
>>> Unix players. HP-UX and AIX both work perfectly well with RAC too. You
>>> even investigate VMS, though it tends to lag release timeframes compared
>>to Unix
>>> environments.
>>> Win2K I can't say too much about, because it's not something I've had a
>>lot of
>>> experience with in the clustered environment. I'm still not convinced
>>it's as
>>> robust as Linux, Unix or VMS, anyway.
>>> HTH. Additions and corrections welcome.
>>> Pete
>>> SELECT standard_disclaimer, witty_remark FROM company_requirements;
>HTH. Additions and corrections welcome.
>SELECT standard_disclaimer, witty_remark FROM company_requirements;

HTH. Additions and corrections welcome.


SELECT standard_disclaimer, witty_remark FROM company_requirements; Received on Thu Jul 11 2002 - 15:21:19 CDT

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