Raw device to ASM

Hi,
How can i move the "RAW device" Migrating to ASM
what are the steps to be followed
Oracle Version : 11.1.0.7.0
Platform: AIX 6.1
Thanks,
Ramesh

Aman.... wrote:
ASMLIB is not mandatory to use the raw device with ASM. Its an "add-on" to improve the performance, that's all!Not really a performance improvement as it cannot make ASM I/O go any faster - it is a more a management driver that enables you to manage ASM disks/LUNs via an ASM command line interface. But as you said, it is not mandatory. I personally prefer using udev and multipath directly on Linux for configuring and maintaining device names and permissions for all disks and LUNs and not treat ASM ones differently via another interface.
Also, as ASMlib is a kernel module, it is another moving part at boot time. It needs to match the kernel version used. It and other similar kernel drives need to "+play nice+" with one another. And this is the primary reason we've stopped using ASMlib after we first tried it with 10.1 RAC. There were incompatibilities between it and a vendor kernel driver, resulting in adhoc ASM I/O errors. And the Metalink Note at the time stated that there are no incompatibilities between ASMlib and such vendors drivers... (and I did request Support to amend that note after the incompatibility was identified via a SR, but it never was).

Similar Messages

Is database using File system, RAW devices or ASM?

Hi there
Is is possible to find out if the database is using File system, RAW devices or ASM for storage?
I think for ASM, we can tell by querying the V$DATAFILE view if it has ' DATA ' or something like that (a name that has ' ' prefixed to it). Is this the only way? How about other sotrage types (RAW and Filesystem)?
Thanks in advance!

user12033597 wrote:
I think for ASM, we can tell by querying the V$DATAFILE view if it has ' DATA ' or something like that (a name that has ' ' prefixed to it). Is this the only way? How about other sotrage types (RAW and Filesystem)?V$DATAFILE or DBA_DATA_FILE
Raw depends on your OS - in *nix, likely something like /dev/sdc1
ASM depends on ASM and will include + and will follow an ASM pattern, such as described http://docs.oracle.com/cd/B19306_01/server.102/b14200/clauses004.htm
File depends on OS - in *nix, likely start with a '/' and NOT be in /dev or /proc. In Winders start with C:\ or some other disk path.
Nicely discussed in the docs in the Administrators Guide found at http://tahiti.oracle.com

ASM cannot find the raw devices nor ASM drives

Hi,
We are trying to use ASM on linux. The kernel version is
2.6.9-42.0.10.0.1.ELsmp x86_64.
We tried both raw devices and ASM drives. But after all the tries, the installer simply will not list the disks.
Anybody can help? Thanks.

"I had installed ASM initially on the same CRS, but due to some error during the installation"
This statement means: I had installed ASM on the clusterware, but due to time synchronization error, it didn't got copied on to the 2nd node, and hence I had to uninstall the ASM software.
But the clusterware is still up and running.
Amit.

Raw device in ASM

Hi,
I am assigning raw devices to ASM on IBM-AIX 5.2. But the devices are not visible in ASM. Please somebody help me how to identify the disks in ASM or from AIX to check whether the disks are accessiable. I am able to ls -lrt and find the disk. but not able to identify the raw disk size
Thanks for your help

In some OSs raw devices are only visible to root unless the permissions are explicitly reset.
Have you read the appropriate section in the RAC install guide for AIX? (http://download.oracle.com/docs/cd/B19306_01/install.102/b14201/storage.htm#BABHCGIJ)

Raw Device and ASM configuration

Can any body send me steps/commands to configrue Raw device and then ASM on top of it for RAC?

Try this:
http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14231/storeman.htm#i1021337
And this for installing 10g RAC on RH:
http://www.puschitz.com/InstallingOracle10gRAC.shtml
Daljit Singh

How to converrt files on RAW devices in ASM to non ASM file system.

Hi all,
I have on problem .
Is that possible to migrate ASM raw files system to non ASM file .
If possible plzz describe them.
If not also please tell y not?
Thanks in addvance
Regards
Krishna

Hi,
I totally agree with Mahir. And I just want to share one thing:
Use %U to generate guaranteed unique names :
For backupsets, %U means: %u_%p_%c
For an image copy of a datafile, %U means: data-D-%d_id-%I_TS-%N_FNO-%f_%u
For an image copy of an archived redolog, %U means: arch-D_%d-id-%I_S-%e_T-%h_A-%a_%u
For an image copy of a control file, %U means: cf-D_%d-id-%I_%u
Thank you

Node is not able to identify new raw device in ASM

Hello experts,
i have a strange probelm with raw disk discovery in ASM. i have a six node cluster. and we are planning to add another raw disk to support database
growth.
out of 6 nodes, 5 nodes are able to find raw disk and on 6th node, it is not able see the disk. not sure what could be the problem.
i have verified the file permissions. i did see 640 and these seems to be correct
My database version : 10.2.0.4
OS RHEL 4.7
here is the info.:
on NOde 5 :
SQL> SELECT name, header_status, path FROM V$ASM_DISK;
NAME HEADER_STATU PATH
MEMBER /dev/raw/raw22
MEMBER /dev/raw/raw21
CANDIDATE */dev/raw/raw23*
FOREIGN /dev/raw/raw5
FOREIGN /dev/raw/raw4
FOREIGN /dev/raw/raw3
FOREIGN /dev/raw/raw2
FOREIGN /dev/raw/raw1
on node 6 :
SQL> SELECT name, header_status, path FROM V$ASM_DISK;
NAME HEADER_STATU PATH
FOREIGN /dev/raw/raw5
FOREIGN /dev/raw/raw4
FOREIGN /dev/raw/raw3
FOREIGN /dev/raw/raw2
FOREIGN /dev/raw/raw1
please guide me..
#! Kumar

The disk attribute reserve_policy may need to be modified for the disk.
Verify if the value of reserve_policy is "single_path"
lsattr -El diskname | grep reserve_policy
if it is, then change it as follows
chdev -l diskname -a reserve_policy=no_reserve
This will ensure the disk is sharable across multiple nodes.

Oracle ASM installation and raw device options

I am looking to install Oracle ASM on Linux Red Hat AS 4 (ia64) using Oracle 10.2.0.3.
A general question I have regarding prerequisites for ASM using raw devices. It appears there are 2 options for dealing with RAW devices.
1. Use the ASM library driver
or
2. simply bind the devices to raw devices (and then install a new $OH with an ASM instance)
Is there a recommendation from Oracle, industry best practices, expert opinions on which way to go?
If I understand correctly it sounds like option 2 will require an ASM $OH and instance. Is that right or do both option require this?
Can someone provide guidance as to which option I should use, an Oracle whitepaper, a recommendation, instructions or something.
Any help or insight is provided as to which option I should use.
Thank you.
echardrd

OK. Perhaps I am a little condused then. From what I read Oracle ASM recommends the use of RAW devices for ASM storage devices. What I have is a new LUN presented to my database server from the SAN. I assumed that the LUN needs to be mounted in some fashion on the server, but my SA tells me in order to mount it, would require the use of a filesystem. If we put a filesystem(NTFS, ext, etc) on the LUN prior to mounting it, will ASM be able to use it? If ASM can use a device that has a filesystem on it will this add unneccessary overhead (I/O)?
I guess my question is for ASM should I
1. use a RAW partition or a filesystem? Does it matter?
2. Will RAW have better I/O performance?
3. How do i make the LUN presentation from the SAN a usable RAW device to my database server? Any steps or guidance would be helpful since my SA and I can not seem to bridge this gap.
Thanks.

CREATING RAW DEVICE IN LINUX

HI ALL,
in redhat linux 5 how to format the disk(ex: /opt,/u01,.....) and make it as raw device for ASM installation

DSP_863977 wrote:
HI ALL,
in redhat linux 5 how to format the disk(ex: /opt,/u01,.....) and make it as raw device for ASM installationit is not possible to change a mount /opt or /u01 for ASM storage.
for learning purpose you can learn with vmware server to create a raw device to configure/install ASM.
Refer the link:- shared storage part for linux5/rhel5
http://oracleinstance.blogspot.com/2010/03/oracle-10g-installation-in-linux-5.html
for more information refer the link:-
http://download.oracle.com/docs/cd/B28359_01/server.111/b31107/asmprepare.htm

Configuring Storage for Clusterware on Raw devices

My proposed system is:
- Sun Solaris 10
- Oracle 10G RAC
- Oracle Clusterware
- Raw devices for Clusterware files
- ASM for database flies
Assume I have appropriately sized LUNs assigned on my SAN for OCR and voting disks. My question is, how do I configure the raw devices required for these Clusterware files?
I have read the Oracle RAC/Clusterware installation guide (Sun Solaris, SPARC), which goes as far as identifying the requirements but does not give the procedure. If I wish to use raw devices for ASM, it gives a procedure for creating partitions on the LUNs. Is anything like this required for the Clusterware files (OCR and voting disks)?

As far as I know, Solaris follows the traditional raw device definition, which basically says that a raw device is a disk or a partition on a disk that does not contain a file system (yet). Given your question, this would mean that any device that you can find that does not contain a file system would be a raw device.
Message edited here:
However, you need to find the right link to this device in order to use it as a raw or character device. Otherwise, the device would be used as a block device, which means it will be buffered.
On Solaris, those character devices should be listed under /dev/rdsk, while the block device would be listed under /dev/dsk. (Please, refer to: http://www.idevelopment.info/data/Unix/Solaris/SOLARIS_UnderstandingDiskDeviceFiles.shtml)
End of update.
Therefore, you have 2 options in your case. You can create LUNs in your storage that would be just suitable to host your Voting Disks and OCRs OR you can create a bigger LUN and put an OCR and a Voting Disk on this one, AFTER you have sliced the disk (LUN) using the format command.
There is only one thing to remember: If you follow Oracle's recommendation to use multiple Votings and mirrored OCRs, it would obviously be better that those devices do not all share the same LUN (for availability reasons).
Last but not least, you may want to have a look at the following forum for a similar discussion on using RAW devices under Solaris: http://forum.java.sun.com/thread.jspa?threadID=5073358&messageID=9267900
Hope that helps. Thanks.
Message was edited by:
MarkusM

Database Data files on RAW Devices

Hi,
I'm creating a database and wish to locate the tablespaces on a raw device.
How do I specify the datafiles for the tablespaces on the raw device.

> Any reason for moving to raw device?
I actually prefer raw devices and ASM over using cooked file systems.
By default RAW devices eliminate the "interference" of the kernel. It does not manage a file system on the device. There are no other foreign processes that can use that raw device (as is often the case with cooked devices). There is no o/s file system cache for that device. A physical I/O on the Oracle side means a dinkum physical I/O and not a maybe-logical-I/O-from-the-file-system-o/s-cache.
There is no need for me as DBA to manage that file system according to OFA standards (ASM does it for me). There is no need for me to go through the learning curve of using a 3rd party volume manager. I have features like automated load balancing while the instance is up and running.
Yes, there is an argument to be made for just how much of a performance improvement in I/O one can get from a raw device versus a cooked file system. But I/O performance is not the only consideration.

10g ASM on Logical Volumes vs. Raw devices and SAN Virtualization

We are looking at setting up our standards for Oracle 10g non-rac systems. We are looking at the value of Oracle ASM in our environment.
As per the official Oracle documentation, raw devices are preferred to using Logical Volumes when using ASM.
From here: http://download.oracle.com/docs/cd/B19306_01/server.102/b15658/appa_aix.htm#sthr
ef723
"Note: Do not add logical volumes to Automatic Storage Management disk groups. Automatic Storage Management works best when you add raw disk devices to disk groups. If you are using Automatic Storage Management, then do not use LVM for striping. Automatic Storage Management implements striping and mirroring."
Also, as per Metalink note 452924.1:
"10) Avoid using a Logical Volume Manager (LVM) because an LVM would be redundant."
The issue is: if we use raw disk devices presented to ASM, the disks don't show up as used in the unix/AIX system tools (i.e. smit, lspv, etc.). Hence, when looking for raw devices on the system to add to filesystems/volume groups/etc., it's highly possible that a UNIX admin will grab a raw device that is already in use by Oracle ASM.
Additionally, we are using a an IBM DS8300 SAN with IBM SAN Volume Controller (SVC) in front of it. Hence, we already have storage virtualization and I/O balancing at the SAN/hardware level.
I'm looking for a little clarification to the following questions, as my understanding of their responses seem to confict:
QUESTION #1: Can anyone clarify/provide additional detail as to why Logical volumes are not preferred when using Oracle ASM? Does the argument still hold in a SAN Virtualized environment?
QUESTION #2: Does virtualization at the software level (ASM) make sense in our environment? As we already have I/O balancing provided at the hardware level via our SVC, what do we gain by adding yet another level of I/O balancing at the ASM level? Or as in the
arguments the Oracle documentation makes against using Lvm, is this an unnecessary redundant striping (double-striped or in our case triple-striped/plaid)?
QUESTION #3: So does SAN Virtualization conflict or compliment the virtualization provided by ASM?

After more research/discussions/SR's, I've come to the following conclusion.
Basically, in an intelligent storage environment (i.e. SVC), you're not getting a 100% bang for the buck by using ASM. Which is the cat's meow in a commodity hardware/unintelligent storage environment.
Using ASM in a SVC environment potentially wastes CPU cycles having ASM balance i/o that is already balanced on the backend (sure if you shuffle a deck of cards that are already shuffled you're not doing any harm, but if they're already shuffled - then why are you shuffling them again??).
That being said, there may still be some value for using ASM from the standpoint of storage management for multiple instances on a server. For example, one could better minimize space wastage by being able to share a "pool" of storage between mulitiple instances, rather than having to manage space on an instance-by-instance (or filesystem by filesystem) level.
Also, in the case of having a unfriendly OS where one is unable to dynamically grow a filesystem (i.e. database outage required), there would be a definite benefit provided by ASM in being able to dynamically allocate disks to the "pool". Of course, with most higher-end end systems, dynamic filesystem growth is pretty much a given.
In the case of RAC, regardless of the backend, ASM with raw is a no-brainer.
In the case of a standalone instance, it's a judgement call. My vote in the case of intelligent storage where one could dynamically grow filesystems, would be to keep ASM out of the picture.
Your vote may be different....just make sure you're putting in a solution to a problem and not a solution that's looking for a problem(s).
And there's the whole culture of IT thing as well (i.e. do your storage guys know what you're doing and vice versa).....which can destroy any technological solution, regardless of how great it is.

10.1.0.3 on RH4(Centos) + Raw devices + ASM + RAC

Hi,
I'm just wondering if anyone here tried installing a single node RAC on 2 instance using ASM on Oracle 10g (10.1.0.3)?
I am using RH4(CENTOS 4.1), Oracle 10.1.0.3 + CRS 10.1.0.3 on fake raw devices in Linux.
I have been able to install the CRS and Oracle database software successfully.
All CRS services and listener are up and running.
crs_stat command return successful results.
srvctl status nodeapps -n <node_name> also returns successful results.
However, when I attempt to startup the ASM instance, I keep encountering these errors:
ORA-00603:ORACLE server session terminated by fatal error
ORA-27504:IPC error creating OSD context
The ORA-00603 error message will appear immediately in the SQLPLUS prompt when I try to startup ASM instance.
Both errors will be logged in alert.log and trace files, no other useful error messages besides these errors.
When I attempt to create a normal database instance using datafiles on the same machine, these errors also appear again!
So, I figure its got nothing to do with the raw devices since my OCR location and Voting devices are using the same raw devices on Linux.
Anyone did the same thing like me and faced similar problems.... please help.
Cheers

You can use dbca to create ASM instance to get rid of the manual copy business.
In realease 1, you can invoke dbca, choose database instance and walk through still you reach storage clause and choose asm and DBA will create ASM instance on both nodes.
Ensure that you choose cluster install option and all the nodes at the initial stages.

ASM spfile on raw device

How do you create a spfile on a raw device, or how do you move one to it?
Any help will be appreciated.
Thanks

Hi all,
maybe I am the only one, but as I understood Alexander's question, he wants to put the ASM spfile on a RAW device, not the database spfile - but I might be wrong. Alexander?
An ASM spfile cannot be kept in a diskgroup. However, if you choose to manage the ASM environment using DBCA, you can specify a shared location for the ASM spfile in course of the initialization of the ASM environment (when you create your ASM instances for the first time using DBCA).
Once the ASM environment has been created, one may use Ned's approach to relocate a spfile of an ASM environment as well. I am not too sure, but I would think that the sqlplus command "create spfile='RAW device' from pfile; would do the trick, too, given that you have a pfile. Now, if you have a spfile only right now, you can create a pfile first using this command and create the spfile in the final destination later. However, in either case, do not forget to change the pfile link after you have performed those steps.
Just my 2 cents. Thanks,
Markus

Question(s) related to ASM, Raw devices and performance

Good morning,
I was recently getting acquainted with ASM. Since I was doing this in "play" VM boxes, it was not possible to draw any conclusions about any performance improvements.
I'd like to know what performance improvements forum members may have experienced after migrating a production environment from a non-ASM setup to an ASM setup.
It would seem that since ASM is a "form" of raw device access that the increase in performance should be noticeable. Was that the case for those who migrated to it ? Was the performance improvement worth it or did it only make managing the database easier ?
Thank you for your contributions on the subject,
John.

ASM uses disk groups to store datafiles; an ASM disk group is a collection of disks that ASM manages as a unit. Within a disk group, ASM exposes a file system interface for Oracle database files. The content of files that are stored in a disk group are evenly distributed, or striped, to eliminate hot spots and to provide uniform performance across the disks. The performance is comparable to the performance of raw devices.
You can add or remove disks from a disk group while a database continues to access files from the disk group. When you add or remove disks from a disk group, ASM automatically redistributes the file contents and eliminates the need for downtime when redistributing the content.
I hope the links below will helps you.
refer the links:
http://download.oracle.com/docs/cd/B28359_01/server.111/b31107/asmcon.htm
http://oracleinstance.blogspot.com/2009/12/rac-file-system-options-basic-concept.html
http://www.dbasupport.com/oracle/ora10g/ASM01.shtml
also you will get more information from book:
Oracle Automatic Storage Management: Under-the-Hood & Practical Deployment Guide (Osborne ORACLE Press Series)
Nitin Vengurlekar (Author), Murali Vallath (Author), Rich Long (Author)
http://www.amazon.com/Oracle-Automatic-Storage-Management-Under/dp/0071496076

Raw device to ASM

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