# mount -t tmpfs shmfs -o size=7g /dev/shm
Also, to make this change persistent across system restarts, add an entry in /etc/fstab similar to the following:
shmfs /dev/shm tmpfs size=7g 0
2. This error may also occur if /dev/shm is not properly mounted. Make sure your df output is similar to the following:
$ df -k
Filesystem 1K-blocks Used Available Use% Mounted on
...
shmfs 6291456 832356 5459100 14% /dev/shm
3. If configuring AMM is not possible due to lack of space on /dev/shm mount point, you can configure ASMM instead of AMM, i.e. set SGA_TARGET, SGA_MAX_SIZE and PGA_AGGREGATE_TARGET instead of MEMORY_TARGET.
| HugePages and Oracle Database 11g Automatic Memory Management (AMM) on Linux [ID 749851.1] | ||
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| Modified 05-NOV-2010 Type BULLETIN Status PUBLISHED | ||
Purpose
Scope and Application
HugePages and Oracle Database 11g Automatic Memory Management (AMM) on Linux
References
Applies to:
Linux OS - Version: 2.6 and later ]
Linux x86
IBM: Linux on System z
IBM S/390 Based Linux (31-bit)
Linux x86-64
Linux Itanium
Purpose
Scope and Application
HugePages and Oracle Database 11g Automatic Memory Management (AMM) on Linux
With AMM all SGA memory is allocated by creating files under /dev/shm. When Oracle DB does SGA allocations that way HugePages are not reserved/used. The use of AMM is absolutely incompatible with HugePages.
Please also note that ramfs (instead of tmpfs mount over /dev/shm) is not supported for AMM at all. With AMM the Oracle database needs to grow and reduce the size of SGA dynamically. This is not possible with ramfs where it possible and supported with tmpfs (which is the default for the OS installation).
If you want to use HugePages make sure that both MEMORY_TARGET / MEMORY_MAX_TARGET initialization parameters are disabled (set to 0) for the database instance.(See also Oracle Database Administrator's Guide 11g)
References
Related
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