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Slowing RMAN Down
Applications can suffer when RMAN is active
Need to throttle back read rate
Use RATE param to limit use of input disk IO
- ALLOCATE or CONFIGURE channel
- Read bytes per second on this channel
- Specify K, M or G
Notes:
RMAN can consume too much of your servers resources and slow down other critical applications. In this situation, you will want to take your foot of the RMAN accelerator. This is accomplished with the RATE parameter of the ALLOCATE CHANNEL command. The Oracle9i Recovery Manager Reference says this about the RATE parameter: “This parameter sets an upper limit for bytes read so that RMAN does not consume too much disk bandwidth and degrade performance.”
My tests showed the slowing affect of the RATE parameter. Note the difference between the two runs:
sys@TEST> @v$backup_async_io
TIME TYPE MAXOPENFILES ET EB
----------- --------- ------------ ---------- ----------
11/28 05:17 AGGREGATE 8 8200 12382907 (RATE = 500k
11/28 05:24 AGGREGATE 8 13300 7634574 (RATE = 10K)