看是比較简单的一个问题，却遭遇了ORA-27300，ORA-27301。因为这个涉及到了有关内核參数kernel.sem的改动。以下是其详细描写叙述。

1、故障现象
OS版本号：SUSE Linux Enterprise Server 10 SP3 (x86_64) - Kernel \r (\l)
DB版本号: SQL*Plus: Release 10.2.0.3.0 - Production 
需求：Processes參数由1000改动到2000
SQL> startup pfile=/u02/database/MRDB/initMRDB.ora;
ORA-27154: post/wait create failed
ORA-27300: OS system dependent operation:semget failed with status: 28
ORA-27301: OS failure message: No space left on device
ORA-27302: failure occurred at: sskgpcreates

2、故障的分析与解决
#起初咋一看还以为空间不够呢，例如以下。显然不是空间的问题，其次有个非常重要的表示"semget"
SQL> ho df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3             1.8T  826G  885G  49% /
udev                   32G  116K   32G   1% /dev
/dev/sda1              99M  9.5M   85M  11% /boot

#后台日志例如以下
Tue Aug  5 18:07:22 2014
Starting ORACLE instance (normal)
Tue Aug  5 18:07:22 2014
Errors in file /u02/database/MRDB/udump/mrdb_ora_30366.trc:
ORA-27154: post/wait create failed
ORA-27300: OS system dependent operation:semget failed with status: 28
ORA-27301: OS failure message: No space left on device
ORA-27302: failure occurred at: sskgpcreates

#Google了一些文章，描写叙述的是须要调整内核參数kernel.sem，也就是信号量的问题

v2012db02u:~ # grep kernel.sem /etc/sysctl.conf
kernel.sem = 1250    32000   100    256     #这个是当前的值

信号量设置演示样例
    SEMMSL应该设置为server中实例中具有最大的PROCESSES參数+10，比如。当最大的PROCESSES參数为5000时，SEMMSL应设置为5010。

SEMMNS參数应设置为SEMMSL*SEMMNI，接上例SEMMSL为5010。SEMMNI的值一般为128。则SEMMNS參数应为（5010*128）=641280。
    SEMOPM參数应设置与SEMMSL參数同样。接上例此处应设置为5010
    因此对于信号量建议做例如以下设置
    sysctl -w kernel.sem="5010 641280 5010 128"

#关于这个參数的详细描写叙述及设置能够參考：Linux 内核參数优化(for oracle)

#因为当前server存在N个实例，因此给了一个比較大的值。生产环境应谨慎改动。例如以下    
v2012db02u:~ # vi /etc/sysctl.conf
v2012db02u:~ # sysctl -p
    ...........
kernel.sem = 7000 1792000 7000 256
    ...........

#再次启动。狂汗....
SQL> startup pfile=/u02/database/MR/initMR.ora;
ORA-00064: object is too large to allocate on this O/S (1,5150880)

v2012db02u:~ > oerr ora 00064
00064, 00000, "object is too large to allocate on this O/S (%s,%s)"
// *Cause:  An initialization parameter was set to a value that required
//          allocating more contiguous space than can be allocated on this
//          operating system.
// *Action: Reduce the value of the initialization parameter.

#从上面的描写叙述来看，不能从os分配连续的空间。

#关于这个问题Metalink(Doc ID 283980.1)上提供了描写叙述信息。须要增大内存分配粒度到16M。
#以下是当前的内存粒度为4M。
SQL> SQL> SELECT x.ksppinm name, y.ksppstvl VALUE, x.ksppdesc descbtion
  2    FROM x$ksppi x, x$ksppcv y
 WHERE     x.inst_id = USERENV ('Instance')
  3    4         AND y.inst_id = USERENV ('Instance')
  5         AND x.indx = y.indx
  6         AND x.ksppinm LIKE '%_ksmg_granule%';

NAME                                VALUE                          DESCBTION
----------------------------------- ------------------------------ --------------------------------------------------
_ksmg_granule_size                  4194304                        granule size in bytes
_ksmg_granule_locking_status        1                              granule locking status

SQL> show parameter sga      #当前sga大小为1G
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_max_size                         big integer 1G
sga_target                           big integer 1G

#Author : Leshami
#Blog   : http://blog.csdn.net/leshami

#直接调整为2G
SQL> show parameter sga
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_max_size                         big integer 2G
sga_target                           big integer 2G

#以下是改动过后内存的粒度。
SQL> set linesize 145
col name format a35
SQL> SQL> col value format a30
col descbtion format a50 wrap
SELECT x.ksppinm name, y.ksppstvl VALUE, x.ksppdesc descbtion
SQL> SQL>   2    FROM x$ksppi x, x$ksppcv y
  3   WHERE     x.inst_id = USERENV ('Instance')
  4         AND y.inst_id = USERENV ('Instance')
  5         AND x.indx = y.indx
  6         AND x.ksppinm LIKE '%_ksmg_granule%';
NAME                                VALUE                          DESCBTION
----------------------------------- ------------------------------ --------------------------------------------------
_ksmg_granule_size                  16777216                       granule size in bytes
_ksmg_granule_locking_status        1                              granule locking status

#再次重新启动DB OK。

3、Doc ID 283980.1

Oracle Server - Enterprise Edition - Version: 9.0.1.0 and later   [Release: 9.0.1 and later ]
Information in this document applies to any platform.

SYMPTOMS

ORA-00064 error is possibly encountered on database startup when the parameter
OPEN_LINKS_PER_INSTNACE is set to over 400.

CAUSE

The contiguous area of storage to be allocated , exceeds the SGA granule 
(subarea) size. The granule size is calculated based on the SGA size. 
SOLUTION

Test case to reproduce the error
================================
a) add OPEN_LINKS_PER_INSTANCE = 1000 in the initora
b) use sqlplus to try starting up the database

This is NOT a BUG.

To fix the issue , increase the size of the SGA to over 128Mb by increasing DB_CACHE_SIZE,
SHARED_POOL_SIZE,LARGE_POOL_SIZE, JAVA_POOL_SIZE, etc.This will cause the granule size to 
be increased to 16Mb.

Workaround
==========
Set the following hidden parameter

_ksmg_granule_size = 16777216

Note:  Please set granule size more than or equal to size showing in the error message.

另外一篇与该错误有关Bug 5959853 - ORA-64 DURING DATABASE STARTUP WITH PROCESSES>6000. DocID:1457812.1