10g ASM IMPLEMENTATION USING LOOPBACK DEVICES - OEL-5.5.pdf

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ASM IMPLEMENTATION USING LOOPBACK DEVICES | OEL 5.5

ASM IMPLEMENTATION WITH LOOPBACK DEVICES

This Tutorial was done on Oracle Linux (OEL-5.5) installed on VMWare for learning purpose. As we know ASM Works on Diskgroup concept which is collection of ASM Disks. ASM Disks are created out of Disk Devices; it could either be LUN's or direct Storage Devices. ASM

can be setup using the ASM Library Driver or RAW Devices. One more option to implement ASM using FAKE RAW DEVICES, but this is NOT recommend Setup for a Production environment.

LOOPBACK DEVICE

A Loop Device is a virtual device (pseudo) which enables a regular file to be accessed as a block device. They would allow us to facilitate a software which needs virtual device as an input. This is possible as in UNIX/Linux Systems, it is possible to use a regular file as a block device. To get light about loop back device from here.

SYSTEM CONFIGURATION

Operating System : Linux – Oracle Linux - 5.5 Kernel Version : 2.6.18-194.el5

Architecture : 32 bit - (i686) Database Version : 10g R2 – 10.2.0.5.0

VIRTUAL FILE SYSTEM

 Create Zero-Filled flat files using dd command.  Attach a loop back device for each file.

For the initial setup of the ASM Disks, execute these commands as OS user root-(#) Make a directory and create the flat files which would represent as disks.

# mkdir –p /u03/asmdisk

# dd if=/dev/zero of=/u03/asmdisk/disk1 bs=1024k count=1000 1000+0 records in

1000+0 records out

1048576000 bytes (1.0 GB) copied, 8.37345 seconds, 125 MB/s

We have created a file with bs*count random bytes, in our case 1024*1000; each of 1GB size. The output will be as follows from the first command, and almost identical for the rest. I want to create 6 files (4 files for +DATA disk group and 2 files for +FRA disk group).

# dd if=/dev/zero of=/u03/asmdisk/disk2 bs=1024k count=1000 # dd if=/dev/zero of=/u03/asmdisk/disk3 bs=1024k count=1000 ..

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We now have six files to be used as virtual disks of 1G each.

# ls -l /asmdisk/*

-rw-r--r-- 1 root root 1048576000 Feb 27 04:00 /asmdisk/disk1 -rw-r--r-- 1 root root 1048576000 Feb 27 05:30 /asmdisk/disk2 -rw-r--r-- 1 root root 1048576000 Feb 27 05:31 /asmdisk/disk3 -rw-r--r-- 1 root root 1048576000 Feb 27 05:45 /asmdisk/disk4 -rw-r--r-- 1 root root 1048576000 Feb 27 05:46 /asmdisk/disk5 -rw-r--r-- 1 root root 1048576000 Feb 27 05:48 /asmdisk/disk6

SETUP LOOPBACK DEVICES

Now we need to make the flat files available as Loopback Devices. # /sbin/losetup /dev/loop1 /u03/asmdisk/disk1

# /sbin/losetup /dev/loop2 /u03/asmdisk/disk2 # /sbin/losetup /dev/loop3 /u03/asmdisk/disk3 # /sbin/losetup /dev/loop4 /u03/asmdisk/disk4 # /sbin/losetup /dev/loop5 /u03/asmdisk/disk5 # /sbin/losetup /dev/loop6 /u03/asmdisk/disk6

The above command will create a loopback device against those files and will map the content of device to these flat files.

# losetup -a /dev/loop1: [0806]:1011842 (/asmdisk/disk1) /dev/loop2: [0806]:1142401 (/asmdisk/disk2) /dev/loop3: [0806]:1142402 (/asmdisk/disk3) /dev/loop4: [0806]:1142403 (/asmdisk/disk4) /dev/loop5: [0806]:1142404 (/asmdisk/disk5) /dev/loop6: [0806]:1142405 (/asmdisk/disk6)

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POINTS TO NOTE

Normally, rc.local contains commands and daemons, we can use it to start a custom service. The rc.local file is executed by the init Process at the end of the System Boot Process. (Almost the last script at boot up). It can be edited by the administrator.

OWNERSHIP & PERMISSIONS

# chown –R oracle:oinstall /u03/asmdisk/ # chmod –R 666 /u03/asmdisk/*

WHAT IS ASMLIB ?

Oracle has developed a storage management interface called the ASMLIB API.

ASMLib is the support library for the ASM. Although ASMLib is NOT mandatory to run ASM. ASMLIB allows an Oracle database using ASM more efficient and capable access to disk groups. ASMLIB is an alternative interface for ASM to access block devices. ASM is capable of referencing disks as raw devices or by using the ASMLib software.

DOWNLOAD ASMLIB RPMS

As I said above, for Linux Systems Oracle provides a custom device driver known as ASMLib, which is recommended for most ASM installations on Linux. Oracle ASMLib is available for Linux; as a kernel module is needed only the supported Linux distributions, the required RPM packages are downloadable. Yes, ASMLib is available for free download from OTN.

Each Linux distribution has its own set of ASMLib packages. OEL 5 uses the Same RPMs as Red Hat Enterprise Linux 5

# cat /etc/issue

Enterprise Linux Enterprise Linux Server release 5.5 (Carthage) # cat /etc/redhat-release

Red Hat Enterprise Linux Server release 5.5 (Tikanga)

There are Several ways to get ASMLIB, we can download it from the OTN here. Oracle ASMLib Downloads for Red Hat Enterprise Linux 5.

For OEL, you can use the public YUM. You would need the internet access over the machine. NOTE: Easy way is to get it from Oracle’s public YUM repository.

We can download it from ULN (Unbreakable Linux Network). If you are not subscribed to ULN and not using Unbreakable Linux then go to the OTN, where you have to select your Linux flavor and then navigate to the exact rpms according to the Linux kernel and then download the required files one by one.

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DOWNLOAD THE ASM LIBRARIES THAT MATCHES OS KERNEL VERSION. ASMLib 2.0 is delivered as a set of 3 RPM packages.

There are 3 packages that one would normally install as part of ASM. oracleasm + oracleasm-support + oracleasmlib



oracleasm (uname –r) # Kernel Driver



oracleaslib # ASM Libraries



oracleasm-support # Support scripts for ASM driver up and running.

It is necessary to pick exact version that matches to our distribution based on kernel and architecture. Within each distribution, each kernel version has a corresponding oracleasm package. First we need to determine which kernel we are using.

# uname -rm

2.6.18-194.el5 i686

The example shows that this is a 2.6.18 kernel, patch level 5, for Enterprise Linux 5 on 32-bit x86 compatible hardware (i686). So I am going to download the oracleasm package corresponding for my kernel version as per above output.

Drivers for kernel 2.6.18-194.el5

oracleasm-2.6.18-194.el5-2.0.5-1.el5.i686.rpm

Next, download the oracleasmlib and oracleasm-support packages for OS version of Linux. All ASMLib installations require those packages appropriate for their machine.

Those are grouped by architecture (AMD64/Intel em64t for x86_64, IA64 for Itanium, and IA32 for x86). At the top of each section is a Library and Tools heading, it is common for all.

Download both of the files under this heading - these are the support utilities and ASM libraries. (oracleasm-support and oracleasmlib, respectively).

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The oracleasm-support package provides the utilities used to get the ASM driver up and running. The oracleasm kernel driver (for the kernel you use. The oracleasmlib package provides the actual ASM library; which provides the ASM discover utility, is not GPL and therefore a separate download and not included in the Linux OS release distribution.

# rpm -Uvih oracleasm-support-2.1.8-1.el5.i386.rpm

warning: oracleasm-support-2.1.8-1.el5.i386.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%] 1:oracleasm-support ########################################### [100%]

# rpm -Uvih oracleasm-2.6.18-194.el5-2.0.5-1.el5.i686.rpm

warning: oracleasm-2.6.18-194.el5-2.0.5-1.el5.i686.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%] 1:oracleasm-2.6.18-194.el########################################### [100%]

# rpm -Uvih oracleasmlib-2.0.4-1.el5.i386.rpm

warning: oracleasmlib-2.0.4-1.el5.i386.rpm: Header V3 DSA signature: NOKEY, key ID 1e5e0159

Preparing... ########################################### [100%] 1:oracleasmlib ########################################### [100%]

LISTING INSTALLED ORACLEASM RPMS

# rpm -qa | grep oracleasm*

oracleasm-2.6.18-194.el5-2.0.5-1.el5 oracleasm-support-2.1.8-1.el5

oracleasmlib-2.0.4-1.el5

CONFIGURE THE ASM KERNEL MODULE.

You must be logged on as the # user to run the oracleasm script. The script calls a number of library functions which are declared in /usr/lib/oracleasm/oracleasm.init.functions. The /etc/init.d/oracleasm script has following options

# /etc/init.d/oracleasm

Usage: /etc/init.d/oracleasm {start|stop|restart|enable|disable|configure|createdisk| deletedisk|querydisk|listdisks|scandisks|status}

configure: Configure ASM. start: Start the ASM service.

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stop: Stop the ASM service.

status: Print the status of ASM service. createdisk: Create an ASM disk.

scandisks: Search for ASM disks. l istdisks: List ASM disks.

querydisk: Query the current status of an ASM disk. deletedisk: Delete an ASM disk.

restart: Restart the ASM service. link: Load the oracleasm module. enable: Enable the ASM service. disable: Disable the ASM service.

ASM is initially configured on each host using /etc/init.d/oraclesam

# /etc/init.d/oracleasm configure -i

Configuring the Oracle ASM library driver.

This will configure the on-boot properties of the Oracle ASM library driver. The following questions will determine whether the driver is loaded on boot and what permissions it will have. The current values will be shown in brackets ('[]'). Hitting <ENTER> without typing an answer will keep that current value. Ctrl-C will abort.

Default user to own the driver interface []: oracle Default group to own the driver interface []: oinstall Start Oracle ASM library driver on boot (y/n) [n]: y Scan for Oracle ASM disks on boot (y/n) [y]: y

Writing Oracle ASM library driver configuration: done

Initializing the Oracle ASMLib driver: [ OK ] Scanning the system for Oracle ASMLib disks: [ OK ]

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ASM IMPLEMENTATION USING LOOPBACK DEVICES | OEL 5.5

# /etc/init.d/oracleasm createdisk ASMD3 /dev/loop3 Marking disk "ASMD3" as an ASM disk: [ OK ]

LISTING & QUERYING LABLED DISKS

# /etc/init.d/oracleasm listdisks ASMD1 ASMD2 ASMD3 ASMD4 ASMD5 ASMD6

# /etc/init.d/oracleasm querydisk ASMD1 Disk "ASMD1" is a valid ASM disk

# /etc/init.d/oracleasm querydisk /dev/loop[1-5]

Device "/dev/loop1" is marked an ASM disk with the label "ASMD1" Device "/dev/loop2" is marked an ASM disk with the label "ASMD2" Device "/dev/loop3" is marked an ASM disk with the label "ASMD3" Device "/dev/loop4" is marked an ASM disk with the label "ASMD4" Device "/dev/loop5" is marked an ASM disk with the label "ASMD5" Device "/dev/loop6" is marked an ASM disk with the label "ASMD6"

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# /etc/init.d/oracleasm querydisk -p ASMD1 Disk "ASMD1" is a valid ASM disk

/dev/loop1: LABEL="ASMD1" TYPE="oracleasm"

# /etc/init.d/oracleasm querydisk -p ASMD4 Disk "ASMD4" is a valid ASM disk

/dev/loop4: LABEL="ASMD4" TYPE="oracleasm"

CONFIGURING TO REINITILIZED THE LOOPBACK DEVICE ON A REBOOT

# vi /etc/rc.local

/etc/init.d/oracleasm createdisk ASMD1 /dev/loop1 /etc/init.d/oracleasm createdisk ASMD2 /dev/loop2 /etc/init.d/oracleasm createdisk ASMD3 /dev/loop3 /etc/init.d/oracleasm createdisk ASMD4 /dev/loop4 /etc/init.d/oracleasm createdisk ASMD5 /dev/loop5 /etc/init.d/oracleasm createdisk ASMD6 /dev/loop6

ASM INSTALLATION BEST PRACTICES

When running more than one database instance on a single server, it’s recommended that you install ASM in its own Oracle home on that server. This is advisable even if you are running only one database instance but plan to add one or more database instances to the server.

With separate Oracle homes, you can upgrade and patch ASM and databases independently, and you can deinstall database software without impacting the ASM instance.

If an ASM instance does not already exist and you can select the OUI option to install and configure ASM only, OUI installs ASM in its own Oracle home.

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ORACLE ASM HOME SETUP

Create a new directory path for $ASM_HOME Change ownership and permissions for ASM_HOME

# mkdir –p /u01/app/oracle/product/10.2.0/asm_1 # chown –R oracle:oinstall /u01/app/oracle/

# chmod –R 755 /u01/app/oracle/product/10.2.0/asm_1 # xhost +

access control disabled, clients can connect from any host # su oracle

CONFIGURE ENVIRONMENT FILES

$ cat ora10.env export ORACLE_BASE=/u01/app/oracle export ORACLE_HOME=$ORACLE_BASE/product/10.2.0/db_1 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$ORACLE_HOME/lib export PATH=$ORACLE_HOME/bin:$PATH export ORACLE_SID=orcl $ cat asm.env export ORACLE_BASE=/u01/app/oracle export ORACLE_HOME=$ORACLE_BASE/product/10.2.0/asm_1 export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$ORACLE_HOME/lib export PATH=$ORACLE_HOME/bin:$PATH export ORACLE_SID=+ASM

Oracle Base and Oracle Homes for ASM Oracle Home and RDBMS Oracle Home

$ORACLE_BASE  /u01/app/oracle

$ORACLE_HOME  /u01/app/oracle/product/10.2.0/db_1 ASM ORACLE_HOME  /u01/app/oracle/product/10.2.0/asm_1

ASM_HOME INSTALLATION

Setup your environment variables to different location mainly ORACLE_HOME and ORACLE_SID

$ export ORACLE_SID=+ASM

$ export ORACLE_HOME=/u01/app/oracle/product/10.2.0/asm_1

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$ ./runInstaller

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Specify Home Details window in the Path field, verify that the complete Oracle Home path is /u01/app/oracle/product/10.2.0/asm_1

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Run the root.sh script as per the instruction to complete the installation.

# /u01/app/oracle/product/10.2.0/asm_1/root.sh Running Oracle10 root.sh script...

The following environment variables are set as: ORACLE_OWNER= oracle

ORACLE_HOME= /u01/app/oracle/product/10.2.0/asm_1 ..

...

[Trimmed]

Entries will be added to the /etc/oratab file as needed by Database Configuration Assistant when a database is created Finished running generic part of root.sh script.

Now product-specific root actions will be performed.

START LISTENER

$ listener start listener_name $ listener start listener

$ listenrt status listener

ASM INSTANCE SETUP FROM ASM_HOME

Invoke DBCA from the ASM Oracle Home (i.e. /u01/app/oracle/product/10.2.0/asm_1)

$ . ./asm.env

$ export ORACLE_SID=+ASM

$ export ORACLE_HOME=/u01/app/oracle/product/10.2.0/asm_1/ $ cd /u01/app/oracle/product/10.2.0/asm_1/

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If the Oracle Cluster Synchronization Service (CSS) is not running, a warning message screen will be displayed. Follow the instruction and Click "OK” button. Once you’ve returned to the previous screen, Click the "Next" button.

EXECUTE LOCAL CONFIG SCRIPT AS # USER

Before creating and starting +ASM instance, CSS service must be up and running so in order to get our CSS service up and running just login as super user (root) run the localconfig utility from $ORACLE_HOME/bin or $ASM_HOME/bin to start CSS service.

# /u01/app/oracle/product/10.2.0/asm_1/bin/localconfig add Successfully accumulated necessary OCR keys.

Creating OCR keys for user 'root', privgrp 'root'.. Operation successful.

Configuration for local CSS has been initialized Adding to inittab

Startup will be queued to init within 90 seconds. Checking the status of new Oracle init process...

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Asking password for +ASM instance

Click ok on the confirmation screen

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Click Yes to close the screen

ASM INSTANCE BACKGROUND PROCESSES

$ ps -ef | grep asm

root 19704 1 0 04:12 ? 00:00:00 /bin/su -l oracle -c sh -c 'cd

/u01/app/oracle/product/10.2.0/asm_1/log/oel-server/cssd; ulimit -c unlimited; exec /u01/app/oracle/product/10.2.0/asm_1/bin/ocssd ' oracle 19807 19704 0 04:13 ? 00:00:00 /u01/app/oracle/product/10.2.0/asm_1/bin/ocssd.bin oracle 20313 1 0 04:33 ? 00:00:00 asm_pmon_+ASM oracle 20315 1 0 04:33 ? 00:00:00 asm_psp0_+ASM oracle 20319 1 0 04:33 ? 00:00:00 asm_mman_+ASM oracle 20321 1 0 04:33 ? 00:00:00 asm_dbw0_+ASM oracle 20323 1 0 04:33 ? 00:00:00 asm_lgwr_+ASM oracle 20325 1 0 04:33 ? 00:00:00 asm_ckpt_+ASM oracle 20327 1 0 04:33 ? 00:00:00 asm_smon_+ASM oracle 20329 1 0 04:33 ? 00:00:00 asm_rbal_+ASM oracle 20331 1 0 04:33 ? 00:00:00 asm_gmon_+ASM root 23421 18532 0 06:03 pts/3 00:00:00 grep asm

$ ps -ef | grep pmon

oracle 20313 1 0 04:33 ? 00:00:00 asm_pmon_+ASM oracle 23771 11228 0 06:17 pts/2 00:00:00 grep pmon

POINTS TO NOTE

ASMRBAL  ASM REBALANCER MASTER PROCESS

It coordinates the rebalancing activity when a new disk is added or removed diskgroup. Now you can see +ASM Instance has been setup successfully and running from $ASM_HOME.

For 10g versions of oracle ASM binaries are shipped with RDBMS binaries so that CSS is started and running from the $ORACLE_HOME by default. In our case its running from ASM_HOME. The CSS service must be running before the ASM Instance Starts. The CSS daemon is required to enable synchronization between ASM instance and RDBMS instance.

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LET’S CREATE DATABASE

$ . ./ora10.env $ dbca

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$ ps -ef | grep asm

root 19704 1 0 04:12 ? 00:00:00 /bin/su -l oracle -c sh -c 'cd

/u01/app/oracle/product/10.2.0/asm_1/log/oel-server/cssd; ulimit -c unlimited; exec /u01/app/oracle/product/10.2.0/asm_1/bin/ocssd ' oracle 19807 19704 0 04:13 ? 00:00:01 /u01/app/oracle/product/10.2.0/asm_1/bin/ocssd.bin oracle 20313 1 0 04:33 ? 00:00:00 asm_pmon_+ASM oracle 20315 1 0 04:33 ? 00:00:00 asm_psp0_+ASM oracle 20319 1 0 04:33 ? 00:00:00 asm_mman_+ASM oracle 20321 1 0 04:33 ? 00:00:00 asm_dbw0_+ASM oracle 20323 1 0 04:33 ? 00:00:00 asm_lgwr_+ASM oracle 20325 1 0 04:33 ? 00:00:00 asm_ckpt_+ASM oracle 20327 1 0 04:33 ? 00:00:00 asm_smon_+ASM oracle 20329 1 0 04:33 ? 00:00:00 asm_rbal_+ASM oracle 20331 1 0 04:33 ? 00:00:00 asm_gmon_+ASM oracle 25870 1 0 07:38 ? 00:00:00 asm_o001_+ASM oracle 25902 1 0 07:38 ? 00:00:00 ora_asmb_orcl oracle 31430 21199 0 08:26 pts/1 00:00:00 grep asm

$ ps -ef | grep pmon

oracle 20313 1 0 04:33 ? 00:00:00 asm_pmon_+ASM oracle 25872 1 0 07:38 ? 00:00:00 ora_pmon_orcl

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CONNECTING RDBMS INSTANCE

$ . ./ora10.env

ORACLE_SID = [orcl] ? orcl $ rlsqlplus / as sysdba

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production With the Partitioning, OLAP and Data Mining options

SYS> select name from v$datafile; NAME --- +DATA/orcl/datafile/system.256.905325775 +DATA/orcl/datafile/undotbs1.258.905325785 +DATA/orcl/datafile/sysaux.257.905325779 +DATA/orcl/datafile/users.259.905325787 +DATA/orcl/datafile/example.265.905326495

SYS> select name from v$controlfile; NAME

--- +DATA/orcl/controlfile/current.260.905326313

+FRA/orcl/controlfile/current.256.905326317

SYS> select member from v$logfile; MEMBER --- +DATA/orcl/onlinelog/group_3.263.905326425 +FRA/orcl/onlinelog/group_3.259.905326451 +DATA/orcl/onlinelog/group_2.262.905326375 +FRA/orcl/onlinelog/group_2.258.905326403 +DATA/orcl/onlinelog/group_1.261.905326323 +FRA/orcl/onlinelog/group_1.257.905326359 6 rows selected.

SYS> show parameter db_recovery_file_dest;

NAME TYPE VALUE

--- --- --- db_recovery_file_dest string +FRA

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CONNECTING ASM INSTANCE

$ . ./asm.env

$ env | grep ORA | sort ORACLE_BASE=/u01/app/oracle

ORACLE_HOME=/u01/app/oracle/product/10.2.0/asm_1 ORACLE_SID=+ASM

$ sqlplus "/as sysdba" ..

...

SYS> select status from v$instance; STATUS

--- STARTED

SYS> show parameter instance_type;

NAME TYPE VALUE

--- --- --- instance_type string asm

SYS> select instance_name from v$instance; INSTANCE_NAME

--- +ASM

SYS> select group_number, name, type, state, total_mb, free_mb from v$asm_diskgroup; GROUP_NUMBER NAME TYPE STATE TOTAL_MB FREE_MB

--- --- --- --- --- --- 1 DATA NORMAL MOUNTED 4000 1628 2 FRA EXTERN MOUNTED 2000 981

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SYS> select group_number, name, allocation_unit_size au_sz, state, type, total_mb, free_mb, offline_disks from v$asm_diskgroup;

GROUP_NUM NAME AU_SZ STATE TYPE TOTAL_MB FREE_MB OFFLINE_DISKS --- --- --- --- --- --- --- --- 1 DATA 1048576 MOUNTED NORMAL 4000 1628 0

2 FRA 1048576 MOUNTED EXTERN 2000 981 0

SYS> show parameter pfile;

NAME TYPE VALUE

--- --- --- spfile string /u01/app/oracle/product/10.2.0 /asm_1/dbs/spfile+ASM.ora

SYS> create pfile='/tmp/init+ASM.ora' from spfile; File created. $ vi /tmp/init+ASM.ora *.asm_diskgroups='DATA','FRA' +ASM.asm_diskgroups='FRA','DATA'#Manual Mount *.background_dump_dest='/u01/app/oracle/admin/+ASM/bdump' *.core_dump_dest='/u01/app/oracle/admin/+ASM/cdump' *.instance_type='asm' *.large_pool_size=12M *.remote_login_passwordfile='SHARED' *.user_dump_dest='/u01/app/oracle/admin/+ASM/udump'

SYS> shut immediate;

ASM diskgroups dismounted ASM instance shutdown

SYS> startup;

ASM instance started

Total System Global Area 83886080 bytes Fixed Size 1272120 bytes Variable Size 57448136 bytes ASM Cache 25165824 bytes ASM diskgroups mounted

ASM instance has its own SGA and background processes.

ASM instance cannot be in open status, it is instance only (only memory is allocated). ASM does NOT have any controlfile and database files for +ASM instance. When in MOUNT state means, database can use the diskgroup. Mount means mounting diskgroups.

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STRIPPING AND MIRRORING

ASM provides Stripping and Mirroring.

ASM is NOT RAID and it does NOT behave exactly as RAID, ASM can be even Smarter.

STRIPPING: It spreads data evenly across all disks in a diskgroup to optimize performance and utilization. This even distribution of database files eliminates the need for regular monitoring and I/O performance tuning. Read more about Stripping and Mirroring.

MIRRORING: ASM does NOT mirror disks but files.

Mirroring means keeping redundant copies/mirrored copies of each extent of the file. Files based redundancy only between Failure Groups within Disk Group. The mirrored copy of each file extent is always kept on different disk from the original copy.

ASM uses Normal Redundancy (2-way), High Redundancy (3-way) and External redundancy.

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STRIPPING AND MIRRORING DIAGRAM