RE: Allocate Channel ... Rate Not Working

From: Sam Bootsma <>
Date: Thu, 10 Jul 2008 11:32:18 -0400
Message-ID: <>


Thanks for the very useful information.  

Can you tell me if the "set limit channel t1 readrate 2" command is persistent? Or is the limit set only for the current RMAN session?  

I don't want it to be persistent.  


Sam Bootsma

Oracle Database Administrator

Information Technology Services
George Brown College

Phone: 416-415-5000 x4933
Fax: 416-415-4836
E-mail: <>

From: Jared Still [] Sent: July 9, 2008 2:14 PM
To: Sam Bootsma
Subject: Re: Allocate Channel ... Rate Not Working    

On Tue, Jul 8, 2008 at 2:06 PM, Sam Bootsma <> wrote:

$ cat dup_disk.rcv

spool log to '../logs/dup_disk.log';

run {

set until time "2008-06-25 7:00:00";

allocate auxiliary channel ch1 type DISK rate 512K;

allocate auxiliary channel ch2 type DISK rate 512K;


I was expecting this to duplicate my database at rate of 1 MB per second. But, the job had to be killed because it was killing performance. After about 50 minutes it had restored 47.68 GB worth of data files. When I did calculations, this came to 16.19 MB per seconds!!!

 Can anybody tell me why? Am I doing something wrong?  

RATE does not work on disk devices, only on SBT devices.

You can use the SET LIMIT commands. These were introduced in 8i. They are not documented, but still work in 10g.

From my notes:

   ML notes 271979.1 and 342301.1
   specify number as MB P/S to read
   RMAN> set limit channel t1 readrate 2

        And in another location the documentation said:


        in release old syntax
preferred current syntax

        9.0.1 ALLOCATE CHANNEL ... READRATE CONFIGURE CHANNEL ... RATE RATE does not work at all in 9i. Never did, never will.

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist

Received on Thu Jul 10 2008 - 10:32:18 CDT

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