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建议使用x86-64 Linux, 如果必须使用32位Linux, 可参考Metalink note 260152.1 Summary About the Large SGA & Address Space on RH Linux
我摘录重点部分给你:
Configuration 5
* RedHat Advanced Server (RHAS) 2.1 (shmfs/tmpfs)
* RedHat Enterprise Linux (RHEL) 3.0 (shmfs/tmpfs, ramfs)
* Configuration : VLM mode + in-memory filesystem (shmfs/tmpfs, ramfs)
* SGA MAX Size 62GB
* Details in Note 211424.1, Note 262004.1
Since shmfs/tmpfs, ramfs is a memory file system, its size canbe as high as the maximum allowable VM size which is 64GB. SGA MAX Size 62GB theoretic (depending on block size) Only the buffer cache part of the SGA can take advantage of the additional memory. For RHEL3/4 to use the VLM option to create a very large buffercache, you have two options (details in Note 262004.1):
* Use shmfs/tmpfs much as you would in RHAS2.1:
mountNote 262004.1):
* Use shmfs/tmpfs much as you would in RHAS2.1:
mount a shmfs with a certain size to /dev/shm, and set the correct permissions. Keep in mind that in RHEL3, shmfs allocate memory is pageable. Better to use tmpfs since there is no need to specify size.
Mount shmfs:
# mount -t
shm shmfs -o size=20g /dev/shm
Edit /etc/fstab:
shmfs /dev/shm shm size=20g 0 0
---- OR ----
Mount tmpfs:
# mount –t tmpfs tmpfs /dev/shm
Edit /etc/fstab:
none /dev/shm tmpfs defaults 0 0
* Use ramfs (Ref. Note 262004.1, Note 259772.1)
ramfs is similar to shmfs, except that pages are not pageable/swappable. This approach provides the commonly desired effect. Ramfs is created by:
# mount -t ramfs ramfs /dev/shm (unmount /dev/shm first).
The only difference here is that the ramfs pages are not backed by big pages.
* When the shmfs/tmpfs,ramfs is available, Oracle server should know whether to use it or not. Need to use the parameter 'use_indirect_data_buffers=true' remains the same;
If any one of DB_CACHE_SIZE, DB_xK_CACHE_SIZE are set, convert them to DB_BLOCK_BUFFERS
* How to use the memory file system shmfs in short,for details see Note 211424.1:
* Mount the shmfs file system as root using command:
# mount -t shm shmfs -o nr_blocks=8388608 /dev/shm
* Set the shmmax parameter to half of RAM size at most 4294967295
# echo 4294967295 >/proc/sys/kernel/shmmax
* Set the init.ora parameter use_indirect_data_buffers=true
* Startup oracle.
* How to use the memory file system ramfs in short, for details see Note 262004.1:
* Mount the shmfs file system as root using command:
% umount /dev/shm
% mount -t ramfs ramfs /dev/shm
% chown oracle:dba /dev/shm
* Increase the "max locked memory" ulimit (ulimit -l)
Add the following to /etc/security/limits.conf:
oracle soft memlock 3145728
oracle hard memlock 3145728
(in case of ssh see details on Note 262004.1)
* Set the init.ora parameter use_indirect_data_buffers=true
* Startup oracle. |
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