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Home -> Community -> Mailing Lists -> Oracle-L -> Re:About parallel server
Dick
As far as I know, at least in Sun, sequent, hp and linux, you need to have control files and redo log files in raw disk. Every instance needs access to other thread's redo log files to do instance recovery for the failed instances. Only if the data is in the raw disk, multiple nodes can share the same disks. Control file is updated by all the instances. Out of curiosity, what OS were you using ? I just read Scott Heisey's email too and realized that you don't need to use raw disks for few platforms such as True64. May be you were one of those platforms?
Rachel is absolutely correct and we have learnt this lesson hard way. But Oracle 9i Real Application cluster ( aka OPS) is supposedly remove these barriers. Cache fusion is a new feature introduced in 8i, by which disk writes due to true ping is avoided by transferring the data directly from one instance to another instance cache,( only for consistent reads in 8i). Oracle 9i apparently introduces cache fusion for read/read, read/write,write/write scenarios also. In this case, there is a probability that the required block to be transferred between the instances just from the buffer cache itself avoiding the disk access. Also Oracle claims that Real application cluster does not need any change in the application design. I am not sure how all this going to play in the real field, but interesting to know.
Thanks
Riyaj "Re-yas" Shamsudeen
Certified Oracle DBA
i2 technologies www.i2.com
"Rachel Carmichael" <carmichr_at_hotmail.com>
Sent by: root_at_fatcity.com
05/30/01 09:50 PM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> cc: Subject: Re:About parallel server
Even more importantly, if you are planning on implementing parallel server just "to increase your processing power" then you are going to be in trouble!
If you haven't specifically designed your application for parallel server, you can end up DECREASING performance by increasing locking and pings.
This is not something you do lightly once an app has been installed into production.
Rachel
>From: dgoulet_at_vicr.com
>Reply-To: ORACLE-L_at_fatcity.com
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Subject: Re:About parallel server
>Date: Wed, 30 May 2001 14:48:03 -0800
>
>Fernando,
>
> Replies included in your original mail, but in addition:
>
> Parallel server is a separately priced option from Oracle and it is
>pricey.
>Second you may need specific software from you OS vendor to coordinate the
>file
>sharing between the servers, again an additional expense.
>
>Dick Goulet
>
>____________________Reply Separator____________________
>Author: "Fernando Papa" <fpapa_at_elsitio.com.ar>
>Date: 5/30/2001 2:07 PM
>
>
>Hi everybody!
>
>I have some questions about parallel server. Now we have only one instance
>"stand-alone" (no parallel), but we are thinking to switch to parallel
>server because we have a couple of sparc 3500 and nobody are using it, and
>we think it's good for increase our processing power.
>
>The problem is I didn't work with parallel server and I have a lot of
>questions about it:
>
>1) Is mandatory to use raw devices for control files, redo logs & data
>files?
>--> Data files yes, redo and control files can be on cooked file system.
>
>2) How we transfer our cooked data files to raw devices data files?
>import/export? or exist another better (fast) method?
>--> To the best of my knowledge your going to have to rebuild the database
>from
>scratch so imp/exp is your only option.
>
>3) If I start with only one node, performance will be the same of one
>single
>instance (no parallel)?
>--> Yes and NO, raw devices run a little faster than cooked files since the
>OS's
>buffer cache is not in the middle.
>
>4) Somebody know how to work with raw devices under solaris? any link? I
>try
>to found someting in metalink but there's no samples...
>--> Working with raw devices is very different from cooked file systems.
>If you
>don't have an experienced Unix admin you could be in serious trouble.
>
>5) What about backup? I can't put tablespaces in backup mode and copy with
>cp... maybe it's time to use rman?
>--> Rman can handle the backups, but a file system level backup is
>different.
>CP does not work anymore, nor does fbackup, or tar. You'll need
>specialized
>software for the purpose.
>
>Thanks in advance!
>
>--
>Fernando O. Papa
>DBA
>El Sitio - Infraestructura
>(54-11) 4339-3854
>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Fernando Papa
> INET: fpapa_at_elsitio.com.ar
>
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Rachel Carmichael INET: carmichr_at_hotmail.com Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Thu May 31 2001 - 10:06:13 CDT
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