As you all may know, ASMLib is a recommended module for Oracle databases running on Linux platforms and it is an embedded module for UEK (Oracle Unbreakable Kernel) users. Oracle announced that (two years ago or so) they will no longer maintain ASMLib for Red Hat compatible kernel but this does not mean that they abandon the project, rather it is mainly related to the effort they need to put in maintaining the module for multiple kernel versions.
A while ago, Oracle added a new feature to ASMLib allowing ASM devices to choose between physical or logical block sizes in I/O operations. This should be, I believe, a fail-back mechanism for SSD devices used as ASM disks. Many SSD devices use 4K block size however Linux still uses default 512 bytes logical block size for those devices in the same way it does for motor disks. In early releases of ASMLib (
oracleasm-support-2.1.7 and earlier), ASM uses physical block size (4K for SSDs). This is still the default behavior in
oracleasm-support-2.1.8 but now sysadmin can choose between physical and logical blocksize by using
[-b|-p] switches in
- -b|—logical-blocks sets logical blocksize usage
- -p|—physical-blocks set physical blocksize usage
Those switches set
/sys/module/oracleasm/parameters/use_logical_block_size which is default to be
false (use physical blocksize). So that
asmlib module can use the value to decide which block size to use.
In the previous post, I have tried to explain how to install Grid Infrastructure on your VirtualBox instance. In this post, before moving to the next post in which I will be explaining RDBMS 11g Release 2 configuration, I wish to look at a new tool shipped with Grid Infrastructure, namely ASMCA(ASM Configuration Assistant).
We will not be going deep with ASMCA in this post but rather it will be just like a first contact with aliens. ASMCA is a very capable and accompanying tool with the new capabilities of ASM like ADVM or ACFS.
Starting with ASMCA
ASMCA is the youngest member of Oracle *CA family. It seems that ASM users will be using it actively for management by the new features in 11g Release 2. Such as,
- ASM Volume (ADVM) Management
- ASM File System (ACFS) Management
- Read-only snapshot management
In Oracle 11g Release 2 you will find that things have changed even for single instance database installation. I will try to illustrate in this series of posts how to install a single instance Oracle 11g Release 2 database to your Linux machines.
As the first part of our installation series, we will start by installing brand new Grid Infrastructure which you might think to be a fancy name for CRS+ASM but you will find out later that it is a bit more.
Here is the sufficient VirtualBox virtual hardware configuration for your 11g Release 2 playground (Keep in mind that this is the bare minimum configuration to have a painless installation. More resource is obviously better):
|Memory||512MB||Although minimum memory requirement for Oracle 11g Release 2 in a real production environment is documented to be 1024M, for all practical requirements of your playground 512MB will be sufficient.|
|Root Disk||16GB||16 GB root disk for OS+SWAP+Oracle Binary space will be sufficient|
|ASM Disks||6x2GB SCSI Disks||We will be doing an ASM based installation so 6 disks over SCSI interface will be enough to simulate a real life experience with ASM.|
You are now ready to start your VirtualBox for Oracle 11g Release 2 installation.
Install Grid Infrastructure
There are a few important tasks in OS level we should complete before starting grid infrastructure installation.
Physical Partition Creation
The first thing is to create physical partitions over your virtual SCSI devices. Actually this is not crucial for ASM installation because ASM can use physical disk as a whole without any partition. However if you wish to create ASMLIB you will need those partitions.
|[root@localhost ~]# fdisk /dev/sda
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won’t be recoverable.Warning: invalid flag 0x0000 of partition table will be corrected by w(rite)Command (m for help): n
p primary partition (1-4)
Partition number (1-4): 1
First cylinder (1-261, default 1):
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-261, default 261):
Using default value 261Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Changing ASM devices ownership to oracle
Physical partitions we have created are owned by root. They should be changed to be owned by ASM user (oracle in our case) in order to make them visible for ASM discovery.
|[root@localhost ~]# ls –la /dev/sd?1
brw-r—– 1 root disk 8, 1 Sep 21 05:03 /dev/sda1
brw-r—– 1 root disk 8, 17 Sep 21 05:03 /dev/sdb1
brw-r—– 1 root disk 8, 33 Sep 21 05:03 /dev/sdc1
brw-r—– 1 root disk 8, 49 Sep 21 05:03 /dev/sdd1
brw-r—– 1 root disk 8, 65 Sep 21 05:03 /dev/sde1
brw-r—– 1 root disk 8, 81 Sep 21 05:03 /dev/sdf1[root@localhost ~]# chown oracle:dba /dev/sd?1[root@localhost ~]# ls –la /dev/sd?1
brw-r—– 1 oracle dba 8, 1 Sep 21 05:03 /dev/sda1
brw-r—– 1 oracle dba 8, 17 Sep 21 05:03 /dev/sdb1
brw-r—– 1 oracle dba 8, 33 Sep 21 05:03 /dev/sdc1
brw-r—– 1 oracle dba 8, 49 Sep 21 05:03 /dev/sdd1
brw-r—– 1 oracle dba 8, 65 Sep 21 05:03 /dev/sde1
brw-r—– 1 oracle dba 8, 81 Sep 21 05:03 /dev/sdf1
In order to make those changes permanent (if you reboot the system Linux will set all device owners back to root otherwise) you should create a udev permission file
|[root@localhost ~]# more /etc/udev/rules.d/99-oracle.rules
KERNEL==”sda”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
KERNEL==”sdb”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
KERNEL==”sdc”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
KERNEL==”sdd”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
KERNEL==”sde”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
KERNEL==”sdf”, OWNER=”oracle”, GROUP=”dba”, MODE=”0660″
Ensure /dev/shm is sufficiently sized
You should ensure that /dev/shm is minimum 256MB for a successful ASM installation (and 512-750M for RDBMS installation) with MEMORY_TARGET parameter.
|[root@localhost ~]# df –ha|
You can resize tempfs online by using
|[root@localhost ~]# mount /dev/shm –o size=750M,remount|
In order to make this mount operation persistent you should modify the tempfs line in /etc/fstab file as follows:
|[root@localhost ~]# cat /etc/fstab | grep tempfs
tmpfs /dev/shm tmpfs size=750m 0 0
Notice that although we have VirtualBox instance with 512M memory, Linux allows us to mount tempfs with a size of 750M. This most probably due to lazy allocation of memory over tempfs.
Create installation directory and set its ownership
Final step is to create our software directory and set the required ownership to it.
|[root@localhost ~]# mkdir -p /u01/app|
|[root@localhost ~]# chown -R oracle:oinstall /u01/app/oracle|
|Choose Install and Configure Grid Infrastructure for a Standalone Server option and click on Next > button.|
|Set Selected Language language to English and click on Next > button.|
|Next step is to perform ASM configuration for your grid. Choose External as the redundancy of DATA diskgroup. Now click on Change Discovery Path… button to define asm_diskstring parameter.|
|Set Disk Discovery Path to /dev/sd?1 and click on OK|
|Since /dev/sd?1 matches all six SCSI partitions and they are not members of any other diskgroup, installer will list all of them as Candidate disks.Check-out /dev/sda1,/dev/sdb1,/dev/sdc1 devices as members disks of DATA diskgroup then click on Next >Other disks will be used for Flash Recovery Area later on.|
|Choose Use same passwords for these account for a simple configuration then set Specify Password and Confirm Password fields to same password strings and click on Next >.I will be using sysadm throughout the post for any Oracle password required.|
|One of the security enhancements introduced in Release 2 is the separation of different levels of ASM access. This defines different roles for “Who can start/stop ASM instance ?”, “Who can add/drop disks to/from diskgroups?” or “Who can use those diskgroups at RDBMS level ?”For the simplicity of installation we will be setting all roles to dba group.Now set all three select lists to dba and click on Next >.|
|Set Oracle Base to /u01/app/oracle and Software Location to /u01/app/oracle/product/11.2.0/grid. Then click on Next >.|
|Next step is unique to first Oracle software installation as you all may know. You should set Inventory Directory (if it is not already set by installer) to /u01/app/oraInventory. Keep oraInventory Group Name as oinstall and click on Next >|
|In this step installer will check the installation prerequisites as it does in previous releases.|
|By 11g Release 2, if any of the prerequisites fail it will be reported in a tree structure with different categories. In my case majority of the kernel settings are automatically managed since I have installed oracle-validated-configuration rpm during OEL installation.Only problem seems to be insufficiently sized core.net.wmem_max which is defined to be the maximum socket send buffer size.When you click on Fix & Check Again button, installer will generate a single shell script for you to correct all fixable errors and after its execution it will recheck for any possible problems left.|
|Run the generated script as root user
When the script is executed click OK to restart the prerequisite check process.
|As you see kernel parameter problem has gone. Other three errors can not be corrected by installer automatically, but we know that those are not critical ones. First one is PhysicalMemory error due to our VirtualBox 512 MB memory size. The second one is insufficient SwapSize that can be by-passed also for a play ground. And the final problem is RunLevel of Linux which is also not a great deal for us.Now check Ignore All and click on Next > (button will be enabled after checking out Ignore All) to continue.|
|On the summary screen confirm that everything is ok and click on Finish to start installation.|
|After installer successfully completes copy,install,link,etc steps it will pop-up a root.sh execution dialog. Run the required scripts as root.
Then switch back to installation dialog and click OK in Execute Configuration scripts dialog to proceed.
|Final tasks for installer will be to configure new HA service for ASM, diskgroup (DATA) and the default listener (on port 1521) which will be automatically configured also .|
|Finally we are done 🙂 Your ASM, default listener, and HA service is ready to be used.|
Post Installation Checks
|[oracle@localhost ~]$ export ORACLE_HOME = /u01/app/oracle/product/11.2.0/grid [oracle@localhost ~]$ export ORACLE_SID = +ASM
[oracle@localhost ~]$ export PATH = $ORACLE_HOME/bin:$PATH
[oracle@localhost ~]$ sqlplus / as sysasm SQL*Plus: Release 188.8.131.52.2 Beta on Mon Sep 21 05:45:58 2009 Copyright © 1982, 2009, Oracle. All right reserved. Connected to:
Oracle Database 11g Enterprise Edition Release 184.108.40.206.2 – Beta
With the Automatic Storage Management option
SQL> select name from v$asm_diskgroup;
Check Default Listener Status
|[oracle@localhost ~]$ lsnrctl status LSNRCTL for Linux: Version 220.127.116.11.0 – Production on 31-OCT-2009 12:05:36 Copyright (c) 1991, 2009, Oracle. All rights reserved. Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC1521)))
STATUS of the LISTENER
Version TNSLSNR for Linux: Version 18.104.22.168.0 – Production
Start Date 31-OCT-2009 11:51:00
Uptime 0 days 0 hr. 14 min. 37 sec
Trace Level off
Security ON: Local OS Authentication
Listener Parameter File /u01/app/oracle/product/11.2.0/grid/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/localhost/listener/alert/log.xml
Listening Endpoints Summary…
Service “+ASM” has 1 instance(s).
Instance “+ASM”, status READY, has 1 handler(s) for this service…
The command completed successfully
Check HA Targets
| [oracle@localhost ~]$ crs_stat -t
Name Type Target State Host
ora.DATA.dg ora….up.type ONLINE ONLINE localhost
ora….ER.lsnr ora….er.type ONLINE ONLINE localhost
ora.asm ora.asm.type ONLINE ONLINE localhost
ora.cssd ora.cssd.type ONLINE ONLINE localhost
ora.diskmon ora….on.type ONLINE ONLINE localhost
Here is the content of my first presentation in Open World 2009:
I am trying to learn Python for some daily scripting activities on Oracle databases. I hope you all familiar with ORM tools available for other programming languages. I have already found a very developer friendly ORM tool for Python called SQLAlchemy. In this post you will find a basic usage of this tool to write better Oracle-Python codes. We will be going through the answer of a simple question:
with my special thanks to Anil Chalil…