Question on Asm Disk Groups

Hello,
I have five 200gb (Total 1 TB) disks on my prod rac environment and we are using 11g 11.1.0.6. These disks have been mounted a while back and the db is currently 50gb full.
My question is i need to unmount one of the disks of 200gb since we are having a shortage of disks at the moment, so i can use it as the flash recovery drive. My understanding with asm is that even if once disk fails the rebalnce act would happen and it would stripe data across four disks without any loss of data or downtime.
We are using external redudancy on these disks and they use Raid 5.
Can i attempt this, if this is possible could you guys give me the best command i can use to do this.
Thx All

Just do an
alter diskgroup <name> drop disk <name>;The documentation states:
DROP DISK The DROP DISK clause lets you drop one or more disks from the disk group and automatically rebalance the disk group. When you drop a disk, Automatic Storage Management relocates all the data from the disk and clears the disk header so that it no longer is part of the disk group.
Note:
If you need to drop more than one disk i strongly recommend to do it in a single step, e.g.
alter diskgroup <name> drop disk <nameA>,<nameB>;Thsi will do the rebalance only once.
Ronny Egner
My Blog: http://blog.ronnyegner-consulting.de

Similar Messages

Share an ASM disk group among multiple nodes

According to Oracle documentation:
*“To share an ASM disk group among multiple nodes, you must install Oracle Cluster ware on all of the nodes, regardless of whether you install Oracle RAC on the nodes”.*
And if I understand it right to share the same ASM storage group from multiple nodes from separate RACs or multiple non-RAC nodes ASM instances in those nodes need to communicate to synchronize ASM related metadata using same technique like cache fusions.
My question is how this ASM communication take place among different ASM instances located in different RACs and standalone servers. Do we have to have some kind of Interconnect settings among the nodes?

Hi,
ASM and database instances require shared access to the disks in a disk group. ASM instances manage the metadata of the disk group and provide file layout information to the database instances.
ASM instances can be clustered using Oracle Clusterware; there is one ASM instance for each cluster node. If there are several database instances for different databases on the same node, then the database instances share the same single ASM instance on that node.
If the ASM instance on a node fails, then all of the database instances on that node also fail. Unlike a file system failure, an ASM instance failure does not require restarting the operating system. In an Oracle RAC environment, the ASM and database instances on the surviving nodes automatically recover from an ASM instance failure on a node.
see this link
http://download.oracle.com/docs/cd/B28359_01/server.111/b31107/asmcon.htm :)

ASM DISK groups set up at O/S level

Hi
I am having couple of questions regarding the ASM.
I was given LINUX Server and asked me to create the ASM DISK groups at O/S level.
Oracle version: Oracle 11g realease 2 with ASM and Stand alone server
O/S: Redhat Lilnux with 64 bit
1.Unix admin has already given the server and gave me the root access also.Now I need to map/set up the ASM DISK groups manually and create them at the O/S level and then INSTALL the ASM software.
a)We are using the asmlib for mapping at o/s level.Can any body give the command to know whether asmlib was installed on the Linux server.
b)How to see the free Partitions on the Linux server and allot them to ASM disks at O/S level and to create it.
2)Should I use two separate users ie . one for Grid infrastructure(Asm) and other for RDBMS Installation.
Say GRID user for Grid Infrastructure(Asm) and ORACLE user for RDBMS Installation.
If so what is the advantage in using different users for ASM and RDBMS installation respectively.
The grid user is a member of these OS groups :asmdba,asmoper, and asmadmin and not dba group
The oracle user is a member of these OS groups :dba and asmdba groups.
ofcourse grid user and oracle user is also a part of oinstall group.
Please find the url which I picked the above information.
http://levipereira.wordpress.com/2010/11/21/installing-the-grid-infrastructure-for-a-standalone-server/
Thanks in advance
Thanks
Veera

First of all you should be using installation guide from oracle which you can find at ..http://www.oracle.com/pls/db112/portal.portal_db?selected=11&frame=
If so what is the advantage in using different users for ASM and RDBMS installation respectively.There are two things, Grid & Database, Oracle wants to separate the administartion for both software, where users who are DBAs should not be allowed to change ASM stuff and vice-versa.
You can use fdisk command to partition the disks, and use # /usr/sbin/oracleasm createdisk command to create the disk.

ASM Disk Group Showing Full at 50%

Hi to all,
I have two sets of ASM disk groups, one I use for the main datafiles and the other I use for recovery.
The datafile ASM group is at 65% capacity. The Other "Recovery" Disk group became full at 50%, exactly half the size?!
Why does the group perform like this. It should be full when the disks are full? And why does the other group perform normally?
Has anyone else seen this problem before with ASM groups.
If anyone needs any more details please just ask me a question about it.
Thanks,
Jamie.

NAME PATH TOTAL_MB FREE_MB % Used DISK_NUMBER REDUNDA
STATE
DATA /dev/mapper/ASM1_V1p 35644 14389
60 9 NORMAL CONNECTED
1
DATA /dev/mapper/ASM14_V1 35644 14381
60 4 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM8_V1p 35644 14416
60 16 NORMAL CONNECTED
1
DATA /dev/mapper/ASM18_V1 35644 14389
60 8 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM16_V1 35644 14363
60 6 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM10_V1 35644 14335
60 0 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM4_V1p 35644 14415
60 12 NORMAL CONNECTED
1
DATA /dev/mapper/ASM15_V1 35644 14403
60 5 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM5_V1p 35644 14369
60 13 NORMAL CONNECTED
1
DATA /dev/mapper/ASM13_V1 35644 14331
60 3 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM2_V1p 35644 14393
60 10 NORMAL CONNECTED
1
DATA /dev/mapper/ASM11_V1 35644 14443
59 1 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM9_V1p 35644 14453
59 17 NORMAL CONNECTED
1
DATA /dev/mapper/ASM17_V1 35644 14401
60 7 NORMAL CONNECTED
p1
DATA /dev/mapper/ASM7_V1p 35644 14443
59 15 NORMAL CONNECTED
1
DATA /dev/mapper/ASM3_V1p 35644 14342
60 11 NORMAL CONNECTED
1
DATA /dev/mapper/ASM6_V1p 35644 14428
60 14 NORMAL CONNECTED
1
DATA /dev/mapper/ASM12_V1 35644 14370
60 2 NORMAL CONNECTED
p1
RECOVERY /dev/mapper/ASM19_V1 139996 139842
0 0 NORMAL MOUNTED
p1
RECOVERY /dev/mapper/ASM22_V1 139996 139842
0 2 NORMAL MOUNTED
p1

Asm disk group recover

Hi,
I am faced a question in a interview about asm.How to recover corrupted asm disk group(all the disk).
Please provide steps to recover.
Thanks

If you don't know the answer, then you may not be qualified to support this type of configuration. Always start with the documentation.
And if you are answering this level of interview question, saying "I don't know, but can learn" will be a lot better than getting in over your head. Because the follow-on questions will show whether or not you are trying to BS your way through the answer. And if they are any good at interviewing, you won't know that you failed until you don't hear back from them.

Reinstalling Oracle 11gR2 RAC Grid Problem - ASM Disks Group

Folks,
Hello.
I am installing Oracle 11gR2 RAC using 2 Virtual Machines (rac1 and rac2 whose OS are Oracle Linux 5.6) in VMPlayer.
I have been installing Grid Infrastructure using runInstaller in the first VM rac1 from step 1 to step 9 of 10.
On the step 9 of 10 in the Wizard, accidentally, I touch the Mouse, and the Wizard is gone.
The directory for installing Grid in the 2 VMs is the same: /u01
In order to make sure everything is correct, I delete entire directory /u01 in the 2 VMs and install Grid in rac1 again.
I have understood it's not the right way to delete /u01. The right way is to follow the tutorial
http://docs.oracle.com/cd/E11882_01/install.112/e22489/rem_orcl.htm#CBHEFHAC
But I have deleted /u01 and need to fix one by one. I install Grid again and get the error message on step 5 of 9 as follows:
[INS - 30516] Please specify unique disk groups.
[INS-3050] Empty ASM disk group.
Cause - Installer has detected the disk group name provided already exists on the system.
Action - Specify different disk group.
In Wizard, the previous Disk Group name is "DATA" and its Candidate disks (5 ASMDISKs) are gone. I try to use a different name "DATA2", but no ASMDISKs come up under "Candidate disks". For "ALL Disks", all ASMDISKs cannot be selected.
I want to use the same ASM disk group "DATA" and don't want to create a new disk group.
My question is:
How to have the previous ASM disks and its group "DATA" come up under "Candidate Disks" so that can use it again ?
Thanks.

Hi, in case this helps anyone else. I got this INS-30516 error too was stumped for little while. I have 2 x 2-node RAC which are hitting same SAN. The first-built RAC has a DATA diskgroup. When went to build second RAC on new ASM disk new DIskgroup (but same diskgroup name DATA) got INS-30516 about diskgroup name already in use etc. Finally figured out all that was required was to restrict diskstring using button in installer to only retrieve the LUNS for this RAC (this was quick and dirty - all LUNS for both RAC being presented to both RAC). Once diskstring only searched for the LUNS required for this RAC only, e.g.
ORCL:DATA_P* (for DATA_PD and FRA_PD)
the error went away.
I also have DATA_DR and FRA_DR presenting to both RAC. Apparently it scans the header and if it finds a diskgroup name that is already in use based on the diskstring scan it will not allow reuse of the diskgroup name since it has no way of knowing that the other ASM disks are for a different RAC.
HTH

Questions on asm disk discovery:

Questions on asm disk discovery:
1）What is the relationship btween asm_diskstring in the init.ora and DiscoveryString in the GPNP profile.xml?
2) Which one of the above two finally accounts for the disk discovery process?
3) We know that asmlib disks are self describing at the disk header. This overcomes the disk name/path persistency issue as we no long need to rely on the path to discover the asm disks, by setting asm_diskstring='ORCL:*' , ASM instance will identify the right disks automatically. However, I am not sure if setting asm_diskstring='ORCL:*' is the most economic way to do the discovery as I am not sure if Oracle will have to probe all the disks on the OS to determine the right disks. If Oracle has to screen all the disks in this way, then I think setting asm_diskstring='<path_to_asmlib_disk>' will be much faster, although this will be open to the persistent problem. Is my understanding correct?
Thanks.

From my understanding all disk you see in /dev/oracleasm/disks are the disks in your system that been discovered by asmlib at discovery stage.
Currently, due to bug 13465545, ASM instance will discover disks from both locations, ASM_DISKSTRING and gpnp profile, which can cause some mess in disk representation for asm. You can check the settings using asmcmd command: dsget, and set to be the same using dsset.
I think its more secure to set ASM_DISKSTRING to only the disks used by asm instance.
ASMCMD> dsget
Regards
Ed

Questions on asm disk discover:

Questions on asm disk discover:
1）What is the relationship btween asm_diskstring in the init.ora and DiscoveryString in the GPNP profile.xml?
2) which one finally accounts for the disk discovery process?
3) We know that asmlib disks are self describing at the disk header. This overcomes the disk name/path persistency issue as we do not rely on the path the discover the asmlib
disks. asm_diskstring='ORCL:*' will identify the right disks. I am not sure if setting 'ORCL:*' is the most economic way as I am not sure if Oracle will have to scan all the disks
on the OS and probe the disks that it has rigths to determine which disks belong to ASM. If Oracle has to screen all the disks in this way, then I think setting
asm_diskstring='<path_to_asmlib_disk>' will be much faster. However, this will be open to the persistent problem. Is my understanding correct?
Thanks.

Questions on asm disk discovery:
1）What is the relationship btween asm_diskstring in the init.ora and DiscoveryString in the GPNP profile.xml?
2) Which one of the above two finally accounts for the disk discovery process?
3) We know that asmlib disks are self describing at the disk header. This overcomes the disk name/path persistency issue as we no long need to rely on the path to discover the asm disks, by setting asm_diskstring='ORCL:*' , ASM instance will identify the right disks automatically. However, I am not sure if setting asm_diskstring='ORCL:*' is the most economic way to do the discovery as I am not sure if Oracle will have to probe all the disks on the OS to determine the right disks. If Oracle has to screen all the disks in this way, then I think setting asm_diskstring='<path_to_asmlib_disk>' will be much faster, although this will be open to the persistent problem. Is my understanding correct?
Thanks.

Difference between ASM Disk Group, ADVM Volume and ACFS File system

Q1. What is the difference between an ASM Disk Group and an ADVM Volume ?
To my mind, an ASM Disk Group is effectively a logical volume for Database files ( including FRA files ).
11gR2 seems to have introduced the concepts of ADVM volumes and ACFS File Systems.
An 11gR2 ASM Disk Group can contain :
ASM Disks
ADVM volumes
ACFS file systems
Q2. ADVM volumes appear to be dynamic volumes.
However is this therefore not effectively layering a logical volume ( the ADVM volume ) beneath an ASM Disk Group ( conceptually a logical volume as well ) ?
Worse still if you have left ASM Disk Group Redundancy to the hardware RAID / SAN level ( as Oracle recommend ), you could effectively have 3 layers of logical disk ? ( ASM on top of ADVM on top of RAID/SAN ) ?
Q3. if it is 2 layers of logical disk ( i.e. ASM on top of ADVM ), what makes this better than 2 layers using a 3rd party volume manager ( eg ASM on top of 3rd party LVM ) - something Oracle encourages against ?
Q4. ACFS File systems, seem to be clustered file systems for non database files including ORACLE_HOMEs, application exe's etc ( but NOT GRID_HOME, OS root, OCR's or Voting disks )
Can you create / modify ACFS file systems using ASM.
The oracle toplogy diagram for ASM in the 11gR2 ASM Admin guide, shows ACFS as part of ASM. I am not sure from this if ACFS is part of ASM or ASM sits on top of ACFS ?
Q5. Connected to Q4. there seems to be a number of different ways, ACFS file systems can be created ? Which of the below are valid methods ?
through ASM ?
through native OS file system creation ?
through OEM ?
through acfsutil ?
my head is exploding
Any help and clarification greatly appreciated
Jim

Q1 - ADVM volume is a type of special file created in the ASM DG. Once created, it creates a block device on the OS itself that can be used just like any other block device. http://docs.oracle.com/cd/E16655_01/server.121/e17612/asmfilesystem.htm#OSTMG30000
Q2 - the asm disk group is a disk group, not really a logical volume. It combines attributes of both when used for database purposes, as the database and certain other applications know how to talk "ASM" protocol. However, you won't find any general purpose applications that can do so. In addition, some customers prefer to deal directly with file systems and volume devices, which ADVM is made to do. In your way of thinking, you could have 3 layers of logical disk, but each of them provides different attributes and characteristics. This is not a bad thing though, as each has a slightly different focus - os file system\device, database specific, and storage centric.
Q3 - ADVM is specifically developed to extend the characteristics of ASM for use by general OS applications. It understands the database performance characteristics and is tuned to work well in that situation. Because it is developed in house, it takes advantage of the ASM design model. Additionally, rather than having to contact multiple vendors for support, your support is limited to calling Oracle, a one-stop shop.
Q4 - You can create and modify ACFS file systems using command line tools and ASMCA. Creating and modifying logical volumes happens through SQL(ASM), asmcmd, and ASMCA. EM can also be used for both items. ACFS sits on top of ADVM, which is a file in an ASM disk group. ACFS is aware of the characteristics of ASM\ADVM volumes, and tunes it's IO to make best use of those characteristics.
Q5 - several ways:
1) Connect to ASM with SQL, use 'alter diskgroup add volume' as Mihael points out. This creates an ADVM volume. Then, format the volume using 'mkfs' (*nix) or acfsformat (windows).
2) Use ASMCA - A gui to create a volume and format a file system. Probably the easiest if your head is exploding.
3) Use 'asmcmd' to create a volume, and 'mkfs' to format the ACFS file system.
Here is information on ASMCA, with examples:
http://docs.oracle.com/cd/E16655_01/server.121/e17612/asmca_acfs.htm#OSTMG94348
Information on command line tools, with examples:
Basic Steps to Manage Oracle ACFS Systems

DBCA did not see the ASM disk group in NODE 2 but see in NODE 1

Are there anyone who encountered creating a database using DBCA with ASM as file system?
Our issue before is in both nodes the DBCA did not see the ASM disk group.
But after setting the TNS_ADMIN in both nodes and running the DBCA as administrator in Node 1, the DBCA able to see now the ASM disk group. Unfortunately, in Node 2 it didn't work out?
So we didn't know why is it from Node 2, the DBCA still didn't see the ASM disk group?Since it is both the same.
Any ideas? Please advise.
For you information, we are using Windows 64-bit, Oracle 11g R2
Thank you in advance for those who will respond.
Edited by: 822505 on Dec 20, 2010 7:47 PM

822505 wrote:
Are there anyone who encountered creating a database using DBCA with ASM as file system?
Our issue before is in both nodes the DBCA did not see the ASM disk group.
But after setting the TNS_ADMIN in both nodes and running the DBCA as administrator in Node 1, the DBCA able to see now the ASM disk group. Unfortunately, in Node 2 it didn't work out?
So we didn't know why is it from Node 2, the DBCA still didn't see the ASM disk group?Since it is both the same.
Any ideas? Please advise.
For you information, we are using Windows 64-bit, Oracle 11g R2
Thank you in advance for those who will respond.
Are the disks given to the ASM are visible from Node2?
Aman....

EM Alert: Warning:+ASM Disk Group requires rebalance

Environment:
O.S Version : HP-UX B.11.31 U ia64
Oracle DB Version : 11.2.0.3.0 , Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
Database files are on : ASM Disk Group
It is about the ASM Diskgroup low disk space alert by Oracle Enterprise Manager.
Message=Disk Group DG_FLASH_01 requires rebalance because at least one disk is low on space.
Metric=Disk Minimum Free (%) without Rebalance
Metric value=18.961548
Disk Group Name=DG_FLASH_01
Severity=Warning
Target Name=+ASM_dbsrver.siva.com
Target type=Automatic Storage Management
There is only 1 LUN assigned to this diskgroup +DG_FLASH_01_.
We have a Oracle Enterprise Manager Grid Control Job MN_DBSRVR_DEL_ARCHIVELOGS runs every 12 hours by 1 AM and again at 1PM daily. It cleans-up the archivelogs older than 3 days old. The FLASH diskgroup is continuously being written with new files for both archivelogs and flashback logs.
If there was multiple disks and a vast difference between the files on the different LUNs then a rebalance would be good to run.
How to address such recurring alert of " *Disk Group DG_FLASH_01 requires rebalance because at least one disk is low on space*. " with _only one LUN on the +ASM Diskgroup_?

As I stated earlier there is only one disk on this diskgroup
DISK_NUMBER      OS_MB   TOTAL_MB    FREE_MB NAME                           PATH
          0      65536      65536      12995 DG_FLASH_01_0000        /devasm/gc/ora_asm_gc_b03_a14_d10_08_36
          0      65536      65536      43064 DG_DATA_01_0000         /devasm/gc/ora_asm_gc_b03_a13_d12_08_35So disk REBALANCE not required
Edited by: Sivaprasad S on Feb 14, 2013 11:46 PM

Oracle ASM disk group

Hi,
Having a multiple Oracle ASM disk group is more beneficial for Oracle database? if no why? if yes why?
Any metalink note if have.
thanks

Any metalink note do you refer?What is your database version?
Please see these docs.
11g ASM New Feature [ID 429098.1]
ASM 11g New Features - How ASM Disk Resync Works. [ID 466326.1]
Thanks,
Hussein

ASM disk group and multiple databases

Hi,
I want to create a second database on my RAC cluster. Can the ASM diskgroups I have defined for use with the first database , service the second database or do I have to create another set of ASM diskgroups for the second dataabase?
Thanks,
Anne

ASM does not have any data files. ASM will store data files required for the RDBMS instance only.
After you have installed the Oracle binaries, (best practice is to have two Oracle homes one for ASM and another for RDBMS), you can create the ASM instances using DBCA and during this process or later can create ASM diskgroups.
( e,g disk1G, disk2G,disk3G,disk4G) using the above four you can create ASM DISK GROUPS..

Recover OCR and VOTE disk after complete corruption of ASM disk groups.

Hi Gurus,
I am simulating a recovery situation to perform recover of OCR and Vote files after complete corruption of ASM related disks and diskgroups. I have setup my environment as follows:\
Environment: RAC
OS: OEL 5.5 32-bit
GI Version: 11.2.0.2.0
ASM Disk groups: +OCR, +DATA
OCR, Vote Files location: +OCR
ASM Redundancy: External
ASM Disks: /dev/asm-disk1, /dev/asm-disk2
/dev/asm-disk1 - mapped on +OCR
/dev/asm-disk2 - mapped on +DATA
With the above configuration in place I have manually corrupted +OCR, +DATA diskgroups with dd command. I used this command to completely corrupt +OCR disk group.
dd if=/dev/zero of=/dev/asm-disk1. I have manual backups as well as automatic backups of OCR and Vote disk. I am not using ASMLib.
I followed this link:
http://docs.oracle.com/cd/E11882_01/rac.112/e17264/adminoc.htm#TDPRC237
When I tried to recover OCR file, I could not do so as there is no such diskgroup which ASM can restore the OCR, Voting disk to. I could not Re-create OCR and DATA diskgroups as I cannot connect to ASM instance. If you have a solution or workaround for my situation please describe it. That will be greatly appreciated.
Thanks and Regards,
Suresh.

Please go through the following document which have the detailed steps to restore the OCR
How to restore ASM based OCR after complete loss of the CRS diskgroup on Linux/Unix systems [ID 1062983.1]

How to move or migrate whole directories between ASM disk groups?

Hello everyone!
I'm playing around with Oracle ASM and Oracle Database (11g R1), I'm a student. This is just for testing purposes.
Computer specifications are:
Processor: Intel Pentium 4 HT 3.00 Ghz.
RAM Memory: 2 GB.
Hard Disk: 250 GB
O.S.: Windows XP Professional Edition SP 2.
I installed Oracle ASM, I created an ASM disk group (+FRA), I installed Oracle Database and I created a testing database. The database is working properly over the ASM disk group. Days ago, I got help about the initialization parameters DB_CREATE_FILE_DEST, DB_CREATE_ONLINE_LOG_DEST_1, DB_CREATE_ONLINE_LOG_DEST_2 and DB_RECOVERY_FILE_DEST, based on their function, I created another 3 ASM disk groups (+FILES, LOG1, LOG2). Currently, the four initialization parameters are pointing to its corresponding ASM disk group. As you can deduce, at the installation moment of the Oracle Database I used the ASM disk group "+FRA" and inside it were created the directories: CONTROLFILE, DATAFILE, ONLINELOG, PARAMETERFILE, TEMPFILE and the SPFile.
My point is I wanna move or migrate the directories DATAFILE, PARAMETERFILE, TEMPFILE and the SPFile to "+FILES", ONLINELOG and CONTROLFILE to "+LOG1" and "+LOG2", this way, the ASM disk group "+FRA" will contain the Flash Recovery Area only. What is the procedure to do this?
Thanks in advance!

user1987306 wrote:
Hello everyone!
My point is I wanna move or migrate the directories DATAFILE, PARAMETERFILE, TEMPFILE and the SPFile to "+FILES", ONLINELOG and CONTROLFILE to "+LOG1" and "+LOG2", this way, the ASM disk group "+FRA" will contain the Flash Recovery Area only. What is the procedure to do this?
Thanks in advance!
Hi,
There are couple of approaches you can use, here is some of them
- To move datafile, start the database in mount state
RMAN > copy datafile '+FRA/xxx' to '+FILES1';
SQL > alter database rename file '+FRA/xxx' to '+FILES1/xxx';
- To move tempfile
SQL > alter tablespace TEMP add tempfile '+FILES1' SIZE 10M;
SQL > alter database tempfile '+FRA/xxx' drop;
- To move onlinelog
SQL > alter database add logfile member '+LOG1' to group 1;
SQL > alter database add logfile member '+LOG2' to group 1;
SQL > alter database drop logfile member '+FRA/xxx';
- To move controlfile
SQL > restore controlfile to '+FILES1' from '+FRA/xxx';
update the spfile to reflect new location of controlfile
Cheers

Question on Asm Disk Groups

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