Category Archives: Linux

ORA-00845: MEMORY_TARGET not supported on this system

SQL> startup nomount;
ORA-00845: MEMORY_TARGET not supported on this system

This error comes up because we tried to use the Automatic Memory Management (AMM) feature of Oracle 11g R2. But it seems that your shared memory filesystem (shmfs) is not big enough.

[oracle@oel6 ~]$ df -h
Filesystem            Size  Used Avail Use% Mounted on
                       43G   15G   26G  37% /
tmpfs                1001M  212M  789M  22% /dev/shm
/dev/sda1             485M   55M  405M  12% /boot
.host:/               245G  126G  119G  52% /mnt/hgfs

We can change the size of that filesystem by issuing the following command:

mount -t tmpfs shmfs -o size=2g /dev/shm

The shared memory file system should be big enough to accommodate the MEMORY_TARGET and MEMORY_MAX_TARGET values, or Oracle will throw the ORA-00845 error. Note that when changing something with the mount command, the changes are not permanent.
To make the change persistent, edit your /etc/fstab file

tmpfs                   /dev/shm                tmpfs   defaults,size=2G         0 0

Now go and enjoy your automatically managed memory configuration!

increase disk size in oracle linux on vmware

Here is video of these procedures

First of all our vmware guest operating system must be in shutdown mode.
we need to add hard disk to our box.
go to settings—>
click add, then choose hard disk.
check option use an existing virtual disk
then choose file which will expand.
add a new hard disk, go to settings and choose our disk, click utilities–expand and write new size.
power on virtual machine.

our guest system doesn’t see a new size
but fdisk shows  the new size

solution :
create new partition on /dev/sda

[root@oel6 ~]# pvcreate /dev/sda3
  Writing physical volume data to disk "/dev/sda3"
  Physical volume "/dev/sda3" successfully created
[root@oel6 ~]# vgextend vg_oel6 /dev/sda3
  Volume group "vg_oel6" successfully extended
[root@oel6 ~]# lvextend -L +18G /dev/vg_oel6/lv_root /dev/sda3  
  Extending logical volume lv_root to 43.60 GiB
  Logical volume lv_root successfully resized
[root@oel6 ~]# resize2fs /dev/mapper/vg_oel6-lv_root 43G
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg_oel6-lv_root is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 3
Performing an on-line resize of /dev/mapper/vg_oel6-lv_root to 11272192 (4k) blocks.
The filesystem on /dev/mapper/vg_oel6-lv_root is now 11272192 blocks long.

check size :

it’s all, enjoy with new size 🙂

How To Resize /dev/shm Filesystem In Linux?

1) Open /etc/fstab with vi or any text editor of your choice
2) Locate the line of /dev/shm and use the tmpfs size option to specify your expected size

tmpfs /dev/shm tmpfs defaults,size=1500m 0 0



tmpfs /dev/shm tmpfs defaults,size=2g 0 0

3) To make change effective immediately, run this mount command to remount the /dev/shm filesystem:

mount -o remount /dev/shm

that’s all.

Scheduling tasks in linux for automating with crontab

Cron is the time-based job scheduler in Unix-like computer operating systems. Cron enables users to schedule jobs (commands or shell scripts) to run periodically at certain times or dates. It is commonly used to automate system maintenance or administration.
crontab commands:

crontab -e      Edit your crontab file, or create one if it doesn’t already exist.
crontab -l      Display your crontab file.
crontab -r      Remove your crontab file.
crontab -v      Display the last time you edited your crontab file. 
                (This option is only available on a few systems.)

A crontab file has five fields for specifying day , date and time followed by the command to be run at that interval.

*     *     *   *    *        command to be executed
-     -     -   -    -
|     |     |   |    |
|     |     |   |    +----- day of week (0 - 6) (Sunday=0)
|     |     |   +------- month (1 - 12)
|     |     +--------- day of        month (1 - 31)
|     +----------- hour (0 - 23)
+------------- min (0 - 59)


min 	hour 	day/month    month    day/week  Execution time
30 	0 	1 	    1,6,12 	* 	– 00:30 Hrs  on 1st of Jan, June & Dec.
0 	20 	* 	      10       1-5 	– 8.00 PM every weekday (Mon-Fri) only in Oct.
0 	0 	1,10,15       * 	* 	– midnight on 1st ,10th & 15th of month
5,10 	0 	10 	      * 	1 	– At 12.05,12.10 every Monday & on 10th of every month

create a cron job:

su - oracle
crontab -e
--add the following line :
00 13 * * * /u01/scripts/

this script will run at 1:00 PM everyday.

after edit crontab file reload cron service

su - 
service crond reload

that’s all. 🙂

install oracle linux 5.5 x64 on vmware 6

to download oracle enterprise linux 5.5 click link :

for downloading this you must have oracle account, it’s standard registration form.

now we have OS (operating system) file let start:

  1.  run vmware, file->new->virtual machine
  2. click next
  3. browse OS  .iso file and click next
  4. choose corresponding options and click next: 
  5.  choose virtual machine name and location for virtual machine files :
  6. specify disk capacity :
  7. click next and finish. now we have virtual machine for oracle linux and now install OS
  8. press enter :
  9. then choose skip and enter
  10. click next, choose language choose, choose keyboard and click YES;
  11. then click next YES;
  12. set hostname and click edit,  set ip address and netmask :
  13. choose region and click next
  14. enter password for root
  15. select customize now and click next
  16. choose this packages:                                                                                                    Desktop Environments                                                                                             GNOME Desktop Environment                                                                          Applications Graphical InternetDevelopment

    Development Libraries

    Development Tools

    GNOME Software Development

    Java Development

    Legacy Software Development

    X Software Development  (Select libxpdevel and openmotif)


    Server Configuration Tools

    Web Server

    Windows File Server

    Base System

    Administration Tools



    Legacy Software Support (select compat-db)

    System Tools  (select sysstat , oracleasm-2.6.18-194.el5-2.0.5-1.el5.x86_64, oracleasm-support-2.1.3-1.el5.x86_64)

    X Window System

17. click next;

18. at last in this installation disable selinux and firewall.

that’s all, Good luck.  😉