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I have allocated 32MB for large pool. Whenever RMAN backup runs, I notice higher PGA memory usage. I read in Oracle guide, large pool is used for RMAN. But when I issue 'select * from v$sgastat where pool = 'large pool'', I saw see the free memory is still 32MB. So how can I make use of large pool for RMAN backup operations? What I need to set?
Amar,
I read the articles you posted, and thought I'd test it out. My results were not what I expected.
Large Pool = 80M
Block Size = 16K
db_file_direct_io_count = 128
Files = 9
Backup_tape_io_slaves = true
Backing up directly to tape.
From the first article, my memory usage should be:
memory(input) = 4 * #files * db_block_size * db_file_direct_io_count
= 4 * 9 * 16*1024 * 128
= 72 Meg
While the backup is running, it only used 278K of the large pool.Code:SQL> select * from v$sgastat where pool ='large pool';
POOL NAME BYTES
----------- -------------------------- ----------
large pool free memory 80000000
SQL> /
What am I missing?Code:POOL NAME BYTES
----------- -------------------------- ----------
large pool free memory 79721424
large pool KSFQ Buffers 278576
Thanks!
Jodie
how many channels are using???
whatz ur filesperset ????
in general we need to allocated 4 buffers per file.
each buffer is db_block_size * multi_block_read_count
for eg:
db_block_size=8 and multi_block_read_count=8 then 64k per buffer
64k * 4 * 2(channels)
This config works fine for me.Rman uses large_pool_size properly
regards,
Vinod
Vinod,
My Filesperset is not set, so it defaults to all my files (9). I am only using 1 channel.
Also, one of the articles Amar listed had the formula using
buffersize = db_block_size * multi_block_read_count
the other had
buffersize = db_block_size * db_file_direct_io_count
My multiblock_read_count is 64. With either formula it doesn't appear I am using as much large pool as it says I should.
Any ideas?
Jodie