Today while working on one of my practice machine, I’ve started receiving error when tried to start-up one of the instance which is on Cooked File system. Error reads about MEMORY_TARGET. To be precise about the error message and code, below is what i was getting second ago.
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system
Below are the steps in sequence what i performed to test and mitigate the error.
1. I’ve checked the pfile of the instance to check MEMORY_TARGET entires and values to discover if there is any problem with the values assigned (I have the AMM enabled in my machine)
*.memory_target=715128832
2. Then i’ve checked error details more closely using OERR utlity to find the cause of the problem and suggestions.
[oracle@localhost dbs]$ oerr ORA 845
00845, 00000, “MEMORY_TARGET not supported on this system”
// *Cause: The MEMORY_TARGET parameter was not supported on this operating system or /dev/shm was not sized correctly on Linux.
// *Action: Refer to documentation for a list of supported operating systems. Or, size /dev/shm to be at least the SGA_MAX_SIZE on each Oracle instance running on the system.
Error clearly points towards the /dev/shm size on OS and asking to set the size of it to atleast SGA_MAX_SIZE on instance running which is 684m.
3. Now when we have the Cause in hand let’s try to fix the problem.
let me check current settings.
[oracle@localhost dbs]$ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
30G 23G 6.0G 80% /
/dev/sda1 99M 55M 40M 58% /boot
tmpfs 664M 154M 510M 24% /dev/shm /*tmps (Temp File Storage area) is in MB’s – CAUSE CLEARED*/
And it’s 664M which is clearly below the SGA_MAX_SIZE = 684m
Some more checks:
[root@localhost ~]# more /etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
4. Let’s try to add up some memory space to tmpfs area.
I’ve added exact 1GB to /etc/fstab entry. Let me check the change
[root@localhost ~]# vi /etc/fstab
[root@localhost ~]# more /etc/fstab
/dev/VolGroup00/LogVol00 / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults 1 2
tmpfs /dev/shm tmpfs defaults,size=1G 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
/dev/VolGroup00/LogVol01 swap swap defaults 0 0
Alrighty, to fix the settings/changes let’s remount /dev/shm
[root@localhost ~]# mount -o remount /dev/shm
[root@localhost ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/VolGroup00-LogVol00
30G 23G 6.0G 80% /
/dev/sda1 99M 55M 40M 58% /boot
tmpfs 1.0G 154M 4.9G 4% /dev/shm
D.O.N.E
5. Now we are done with the change, let’s try to start the instance once again.
[oracle@localhost ~]$ . oraenv
ORACLE_SID = [orcl] ? orcl
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_2 is /u01/app/oracle
SQL> startup
ORACLE instance started.
Total System Global Area 715616256 bytes
Fixed Size 1338924 bytes
Variable Size 482345428 bytes
Database Buffers 226492416 bytes
Redo Buffers 5439488 bytes
Database mounted.
Database opened.
It’s UP!!
Tales From A Lazy Fat DBA 