Measuring MREADTIM system statistic, alternative way

[Why this post: GATHER_SYSTEM_STATS does not gather MREADTIM information from Direct Path Reads]

Oracle can be tuned in a lot of parts and places. One of these is when Oracle is going to choose between reading an index or doing a full table scan.

In this blog I’m not going into depth about all this, but one of the ‘parameters’ here is setting the MREADTIM system statistic to a ‘real life’ value. This value will tell Oracle how fast reading multiple blocks from disk is with all the overhead in between. How many multiple blocks is, is defined by the multi block read count (MBRC) setting. Together with SREADTIM, IOSEEKTIM and MBRC this will have influence in the execution path Oracle will choose.

Continue reading

Data Guard 12c: Warning: standby redo logs not configured for thread 1, Insufficient SRLs

Well, I have configured some 30 ‘Data Guards’ by now, but I never came across this warning, it seems it’s new in 12c:

DGMGRL> validate database cdb1dgsara

  Database Role:     Physical standby database
  Primary Database:  cdb1dgkara

  Ready for Switchover:  Yes
  Ready for Failover:    Yes (Primary Running)

  Future Log File Groups Configuration:
    Thread #  Online Redo Log Groups  Standby Redo Log Groups Status
              (cdb1dgkara)            (cdb1dgsara)
    1         3                       2                       Insufficient SRLs
    Warning: standby redo logs not configured for thread 1 on cdb1dgsara

Hang on, standby redo logs not configured? I have 4 groups! Continue reading

Oracle 12c installation will fail: Error in invoking target ‘irman ioracle’

During the installation of Oracle 12c (12.1) I encountered the following error:

Error in invoking target 'irman ioracle' of makefile
See '/u01/app/oraInventory/logs/installActions2015(...).log' for details.

Inside the logfile the following error is encountered:

INFO: collect2: ld terminated with signal 9 [Killed]

According to metalink doc 2040972.1 this is due to less memory available (in a VM environment). Continue reading

*ALL* Oracle database patches… Linux and Windows… (on Metalink)

Linux and Windows…

Quick Reference To Patch Numbers For Database PSU, SPU(CPU) And Bundle Patches [ID 1454618.1]

This document is getting replaced by Note 2118136.2:
Download Reference for Oracle Database/GI PSU, SPU(CPU), Bundle Patches, Patchsets and Base Releases [ID 2118136.2]

…more Windows

Oracle Database, Networking and Grid Agent Patches for Microsoft Platforms [ID 161549.1]


Happy patching!

ORA-28547 with Instant Client and Amazon Cloud Web Services

Connecting with the Oracle Instant Client 11g to Amazon Cloud Web Services ( can result in the next error:

ORA-28547: connection to server failed, probable Oracle Net admin error

I found that while pinging the host, it was not able to resolve it, but connecting with SQL Developer ( was possible! Strange…

I downloaded the Oracle Instant Client 12c ( and that works. It seems the Oracle Instant Client 11g ( is not able to connect to Amazon Web Services…

Happy connecting!

Booting Oracle VM / Linux (ISOs) with UEFI ‘bios’ does not work

It seems Oracle VM (<=3.3.1 *) and Oracle Linux (<= 5.10/6.6 *) both install ISOs and installed OS’s are not capable of booting when UEFI on the bare-metal hardware is used. I have seen two configurations now where this happened, one using a USB HDD drive capable providing a ISO to boot from as CD/DVD (Zalman ZM-VE300)  and one HP iLO4 (http and local ISO) ‘remote’ booting. Continue reading

Direct NFS, configuring and network considerations in practise

Oracle Direct NFS (dNFS for short) is an NFS Client functionality integrated directly in the Oracle database software, optimizing the I/O (multi)path to your NFS storage without the overhead of the OS client/kernel software.

In this blog post I’ll describe network considerations, configurations and problems I have encountered during set-ups I have done.

dNFS uses two kinds of NFS mounts, the OS mount of NFS (also referred to as kernel NFS of kNFS) and, of course, Oracle’s database NFS mount, Direct NFS or dNFS.

According to [Direct NFS: FAQ (Doc ID 954425.1)] and [How to configure DNFS to use multiple IPs (Doc ID 1552831.1)], an kNFS mount is needed, although Oracle also claims it will also work on platforms that don’t natively support NFS, e.g. Windows… [Oracle Database 11g Direct NFS Client White Paper] (I don’t know how yet…).

Because dNFS implements multipath I/O internally, these is no need for bonding the interfaces to storage via active-backup or Link Aggregation. However, it’s good practice to bond the OS kNFS connection:

1 - eth0 -\
           - bond0 - OS / kNFS
2 - eth1 -/
3 - eth2 --------- - dNFS path 1
4 - eth3 --------- - dNFS path 2

Above schematic shows [How to configure DNFS to use multiple IPs (Doc ID 1552831.1)]:
“A good solution could be to use bonded NICs (…) to perform the mount and then use unbonded NICs via dNFS for the performance critical path.” Continue reading

Update / install Oracle Linux 6.4 corrupts console in Oracle VM 3.x

After updating Oracle Linux 6.3 to 6.4 or installing 6.4 from scratch will give a corrupt (blank) VNC remote console when launching the console from Oracle VM Manager:


As discussed in and Oracle Support note ‘Corrupted VNC console in PVM guests running Oracle Linux 6.4 on Oracle VM’ (Doc ID 1537278.1), this issue is addressed in ‘X Window System Does Not Run in a PVHVM guest’.

Uninstalling the xorg-x11-drv-cirrus guest driver solves the issue

If you uninstall the xorg-x11-cirrus driver from the guest OS, it will solve this issue.

# rpm -ev --nodeps xorg-x11-drv-cirrus

Reboot the guest OS after uninstalling.

Happy Launching!

Remove Oracle Database Options with chopt in 12c

In 10g and 11g Enterprise Edition, one could select which options to install or not to install during the installation process (excl. the 10g ‘custom database’ option, you would get partioning, OLAP and rat). In 12g, one is not able to choose during install anymore, you will get all the options and they must be removed afterwards. Remove / disable them after installing the database software (only), but before creating databases.

The best way to do this is using the ‘chopt’ tool, or when the option is not available, the Oracle Universal Installer must most likely be used. It’s available in Windows and Linux. When using Windows, one can also rename the .dll’s which ‘enable’ the options. It will NOT remove the objects from the database! Continue reading