handling disks for ASM – when DB, Linux and Storage admins work together

A proper management of ASM Disks can be a complicated task.

On DOAG2015 I discussed with Martin Bach about the concept in my current company, where we implemented a setting which is consistent, robust and enables Storage, Linux and DB admins to work together easily.

As we started to think about ASM when 10.1 was out we tried to evaluate our possibility. asmlib was discarded quite early as it only increased complexity without additional (more...)

How to rename ASM disk groups in Exadata

Deployment of Exadata requires you to generate configuration using Oracle Exadata Deployment Assistant (OEDA). Within the same the default  ASM disk groups names are DBFS_DG, RECOC1 and DATAC1. I usually change those to RECO01 and DATA01 as others doesn’t make sense to me and the only place where I find the default ones is on Exadata.

I had an incident last year where the Exadata deployed half way through and names were left by default (more...)

Extent Allocation

Some references on extents dealing with extent trimming, initial extent for parallel load, tablespace fragmentation, etc…


Parallel Load: Uniform or AutoAllocate extents?

Tom Kyte covers this problem in great details in his post Loading and Extents

Initial Extent Size of a Partition Changed to 8MB from 64KB After Upgrade to or Later (Doc ID (more...)

Oracle ASM Rebalance – Turn it up. To 11?


If you’ve ever seen or heard of the movie This is Spinal Tap then you have likely heard the phrase Turn it up to 11.

Why bring this up?

When ASM was introduced as a method for configuring storage for Oracle, one of the features was the ability to rebalance the data across all disks when disks were added or replaced.  The value used to control how aggressively Oracle rebalances the disks is the REBALANCE (more...)

Introducing Oracle ASM Filter Driver

The Oracle ASMFD (Filter Driver) was introduced in Oracle Database and as of the moment it is available on Linux systems only.

Oracle ASM Filter Driver is a kernel module very much like the ASMLIB that resides in the I/O path of the Oracle ASM disks. It provides an interface between the Oracle binaries and the underlying operating environment.

Here are some of the features of ASMFD:

  • Reject non-Oracle I/O

The (more...)

PRCA-1057 : Failed to retrieve the password file location used by ASM

After the Oracle Restart (Grid Infrastructure) upgrade from 11.2. to , you might encounter the below lines in the ASM alert log file

Tue Jun 23 01:16:01 2015
WARNING: unknown state for ASM password file location resource, Return Value: 3
WARNING: unknown state for ASM password file location resource, Return Value: 3

After the upgrade, below command can get the error

[grid@oracle1 ~]$ srvctl config asm
ASM home: <crs home=''>

Restoring a Database to a New Diskgroup

I had the pleasure of rebuilding an Exadata rack for a customer a while back, and it provided a pretty good refresher in backup and recovery for me.  As DBAs, we back up databases all the time, but the restores are performed much less frequently.  In the case of this rack, there were several databases across multiple ASM diskgroups.  One of the goals of the rebuild was to consolidate all of the databases into a (more...)

Migrating tablespaces across endian platforms

T 4 HP-UX IA (64-bit)   Big 13 Linux x86 64-bit   Little[/code]


Set the tablespace EXAMPLE read only


 alter tablespace example read only;

Tablespace altered.

select file_name from dba_data_files;


EXEC SYS.DBMS_TTS.TRANSPORT_SET_CHECK(ts_list=&amp;amp;amp;amp;amp;amp;gt;'EXAMPLE', incl_constraints =&amp;amp;amp;amp;amp;amp;gt;TRUE);

PL/SQL procedure successfully completed.

SELECT * FROM transport_set_violations;

no rows selected

Export the data using the keywords transport_tablespaces


expdp directory=data_pump_dir transport_tablespaces=example dumpfile=hpux.dmp logfile=hpux.log Starting &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;SYS&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;.&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;SYS_EXPORT_TRANSPORTABLE_01&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;: /******** AS SYSDBA

Processing  (more...)

Oracle’s ASM Filter Driver Revisited


Almost exactly a year ago I published a post covering my first impressions of the ASM Filter Driver (ASMFD) released in Oracle, followed swiftly by a second post showing that it didn’t work with 4k native devices.

When I wrote that first post I was about to start my summer holidays, so I’m afraid to admit that I was a little sloppy and made some false assumptions toward the end – assumptions (more...)

Oracle on 4096 (4k) sector disks don’t work (ish)

I recently came across 4K (4096 byte) sector drives. They are a fairly new thing and have come about so drives can exceed the 2TB limit imposed by having 512byte sectors. The details behind this can be found here, in much greater detail than I need to understand.

What I do understand is that Oracle doesn’t deal with 4K sectors (4Kn) very well and it shows up in a couple of ways. Don’t get me (more...)

ASM Rebalance Too Slow? 3 Tips To Improve Rebalance Times


I’ve run into a few customers recently who have had problems with their ASM rebalance operations running too slowly. Surprisingly, there were some simple concepts being overlooked – and once these were understood, the rebalance times were dramatically improved. For that reason, I’m documenting the solutions here… I hope that somebody, somewhere benefits…

1. Don’t Overbalance

Every time you run an ALTER DISKGROUP <NAME> REBALANCE operation you initiate a large amount of I/O workload as (more...)

Primary on FileSystem and Standby on ASM

For one of the client, standby server went down. We had another standby server which was kept down for more than a month. Decision was taken to start the server and apply incremental SCN based backup on the standby database.

The standby was on ASM and the Primary on filesystem.Incremental backup was started from the SCN reported by below query

select min(fhscn) from x$kcvfh;

Once the backup completed, it was transferred to standby, standby (more...)

No Write Permission on ACFS Mount Point

Last night, I managed to create the ACFS Mount Point after resolving the issue "ACFS-9459: ASVM/ACFS is not supported on this os version". But, after creating the ACFS Mount Point, I'm unable to create or touch any files under this ACFS Mount Point.

Though, I tried to touch a file to create files under this ACFS Mount Point using OS User Oracle and Root, it's failing with the following error:

"touch: cannot touch `x': (more...)

ASM Startup Fails With ORA-04031 After Adding CPUs

A few weeks ago we upgraded one of our production server, adding another CPU tray. This brought the number of CPU cores from 80 to 160, and took us from 2Tb of RAM to 4Tb (just in time for Oracle to announce the in-memory database in!).

However when I went to start things up, ASM wasn't starting up, giving me these errors:

ORA-04031: unable to allocate 32 bytes of shared (more...)

ASM Metadata, Internals and Diagnostic Utilities

If you use ASM on a regular basis, you may find that knowledge of the internals can be very useful for advanced troubleshooting and in general to acquire familiarity with the technology. In particular this is even more relevant when using ASM capabilities for data redundancy/mirroring (i.e. when deploying disk groups with normal or high redundancy).

I have first started investigating this topic when deploying 10g RAC databases in 2005. From time to time (more...)

Oracle ASM 12c: New Features

Last week I was lucky enough to be presenting at the UKOUG AIM SIG. There was a decent enough crowd in attendance and there were some really interesting talks and some really good speakers. In particularly I found Chris Lawless speaking on replication a particularly engaging speaker, and Dave Webster really held the audiences attention late in day.

I was giving a presentation on the new features available to you with 12c ASM. The presentation (more...)

Working Around an ASM Startup Problem


I recently hit the problem covered in MOS note “ASM Instance Is Not Coming Up ORA-00064 (1,4468736,Kfchl Array) Kfchl Array (Doc ID 1328620.1)” mid-way through a Grid Infrastructure upgrade from BP16 to BP3 on Exadata. Specifically, it was the application of prerequisite patch 17783101 (required for downgrades) to node 3 that hit the problem. At this point nodes 1 and 2 had been successfully patched (more...)


We have been dealing with a strange ASM  behavior over the past few months across all ASM instances in our multiple Oracle 11gR2 ( Cluster envs on HPUX 11.31 OS. Even a simple and typical ASM task like, adding new disk to ASM disk group, disk group mount/unmount and querying for CANDIDATE asm disks was taking min of 20 minutes, and sometimes infinity time. This behavior caused a lot of performance (more...)

How to Recover Files from a Dropped ASM Disk Group

Topic: This post describes a few tips and techniques on how to recover ASM files from a dropped disk group and an example of how to 'undrop' an ASM disk group

Context: This research stems from a recent case I have investigated where the data disk group of a test (more...)

Openfiler on Virtualbox and 12c Oracle Flex ASM

Original Post can be viewed at Openfiler on Virtualbox and 12c Oracle Flex ASM

Last week Oracle released 12c database and Oracle blogosphere is bustling with lot of people posting details about new versions and setup. I too decided to take plunge and setup my own RAC cluster. I had (more...)