RMAN: ksfqxcre: failure to allocate shared memory

If You Fail to Allocate Shared Memory, Set LARGE_POOL_SIZE

Set this initialization parameter if the database reports an error in the alert.log

stating that it does not have enough memory and that it will not start I/O slaves. The

message should resemble the following:

ksfqxcre: failure to allocate shared memory means sync I/O will be used whenever async I/O to file not supported natively.

When attempting to get shared buffers for I/O slaves, the database does the following

• If LARGE_POOL_SIZE is set, then the database attempts to get memory from the large pool. If this value is not large enough, then an error is recorded in the alert log, the database does not try to get buffers from the shared pool, and asynchronous I/O is not used.
• If LARGE_POOL_SIZE is not set, then the database attempts to get memory from the shared pool.
• If the database cannot get enough memory, then it obtains I/O buffer memory from the PGA and writes a message to the alert.log file indicating that synchronous I/O is used for this backup.

The memory from the large pool is used for many features, including the shared server (formerly called multi-threaded server), parallel query, and RMAN I/O slave buffers.

Configuring the large pool prevents RMAN from competing with other subsystems for
the same memory.
Requests for contiguous memory allocations from the shared pool are usually small (under 5 KB) in size. However, it is possible that a request for a large contiguous memory allocation can either fail or require significant memory housekeeping to release the required amount of contiguous memory. Although the shared pool may be unable to satisfy this memory request, the large pool is able to do so. The large pool
does not have a least recently used (LRU) list; the database does not attempt to age memory out of the large pool.
Use the LARGE_POOL_SIZE initialization parameter to configure the large pool. To see in which pool (shared pool or large pool) the memory for an object resides, query
V$SGASTAT.POOL.

The formula for setting LARGE_POOL_SIZE is as follows:

LARGE_POOL_SIZE = number_of_allocated_channels * (16 MB + ( 4 * size_of_tape_buffer ) )