1 Reply Latest reply: Apr 19, 2013 9:59 PM by rp0428 RSS

    /dev/shm files

    luix97
      Hi i have a Oracle Rac with linux and asm in path /dev/shm i have some files likes
      ora_instnace_name_xxxxx_xx
      anybody knows what is files? and if i can delete?
        • 1. Re: /dev/shm files
          rp0428
          >
          Hi i have a Oracle Rac with linux and asm in path /dev/shm i have some files likes
          ora_instnace_name_xxxxx_xx
          anybody knows what is files? and if i can delete?
          >
          Sure - its your system. Go ahead and delete anything you want.

          Of course if Oracle and your system are actually USING that shared memory system you will likely cause some major problems.

          But if that is not a concern delete them.
          http://www.oracle-base.com/articles/11g/automatic-memory-management-11gr1.php

          You probably want to start reading the Oracle docs first just in case you actually want your system to work
          http://docs.oracle.com/cd/E11882_01/relnotes.112/e23558/toc.htm
          >
          4.3.2 Insufficient Memory Target Errors
          On Linux systems, if the operating system /dev/shm mount size is too small for the Oracle system global area (SGA) and program global area (PGA), then you encounter the following error:

          ORA-00845: MEMORY_TARGET not supported on this system.
          The cause of this error is an insufficient /dev/shm allocation. The total memory size of the SGA and PGA, which sets the initialization parameter MEMORY_TARGET or MEMORY_MAX_TARGET, cannot be greater than the shared memory file system (/dev/shm) on your operating system.

          Background

          Automatic Memory Management (AMM) has been updated in Oracle ASM 11g Release 2. It manages both the SGA and PGA together. It is managed by the Memory Manager Process (MMAN). In this release, note the following changes to AMM:

          It uses MEMORY_TARGET instead of SGA_TARGET

          It uses MEMORY_MAX_TARGET instead of SGA_MAX_SIZE (defaults to MEMORY_TARGET)

          It uses memory allocated by /dev/shm

          If the value of max_target is set to a value greater than the allocation for the /dev/shm size, then you may encounter the error ORA-00845: MEMORY_TARGET not supported on this system.
          >
          DBA guide for Linux
          http://docs.oracle.com/cd/B28359_01/server.111/b32009/appi_vlm.htm
          >
          G.1 Very Large Memory on Linux x86
          Very Large Memory (VLM) configurations allow a 32-bit Oracle Database to access more than 4GB RAM that is traditionally available to Linux applications. The Oracle VLM option for 32-bit creates a large database buffer cache using an in-memory file system (/dev/shm). Other parts of the SGA are allocated from regular memory. VLM configurations improve database performance by caching more database buffers in memory, which significantly reduces the disk I/O compared to configurations without VLM. This chapter shows how to increase the SGA memory using VLM on a 32-bit computer