Re: RMAN - Disk IO Buffer size not what is expected - We want 128K

From: <paul.porcelli_at_scottishwater.co.uk>
Date: 22 Feb 2006 01:33:44 -0800
Message-ID: <1140600824.077503.161890@g44g2000cwa.googlegroups.com>

Hi here,
not sure what you mean by cite so I'm guessing you want me to show you where I've seen this info.
See below from Oracle 9 documentation

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Table 14-1 Disk Buffer Allocation Algorithm If level of multiplexing is . . . Then . . . Less than or equal to 4
 RMAN allocates buffers of size 1 MB so that the total buffer size for all the input files is 16 MB. For example, if FILESPERSET=1, then RMAN allocates 16 buffers for the one file going into the set. If FILESPERSET=4, then RMAN allocates 4 buffers for each of the 4 files in the backup set.

Greater than 4 but less than or equal to 8  RMAN allocates disk buffers of size 512 KB so that the total buffer size for all the files is less than 16 MB.

Greater than 8
 RMAN allocates a fixed 4 disk buffers of 128 KB for each file, so that the total size is 512 KB for each file.

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Received on Wed Feb 22 2006 - 03:33:44 CST