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
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 https://oss.oracle.com/ol6/docs/RELEASE-NOTES-U4-en.html#idp513536 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.
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
I have been trying to run VBoxManage.exe from the Windows Task Scheduler to periodically list vms. The problem I had was that it wouldn’t list the VM’s I had registered, even if the task was run as the user that created the VM’s and with the ‘Run with highest privileges’ selected.
When searching the Internet, I saw more people having difficulties running it this way, so I started experimenting. Using ‘psexec‘ and ‘runas’ (use the /savecred option and run it once manually from command line) did work when running the VBoxManage.exe as the VM’s creator user while being logged as someone else, but running it from the Task Scheduler still did not work. Continue reading
I recently updated to Internet Explorer 10 (Windows 7 64bit) and when I browsed to a website with a security certificate problem: “There is a problem with this website’s security certificate.”, the “Continue to this website (not recommended).” option was missing!!!
The issue here is that Microsoft restricted access to pages which are using a key using less than 1024 bits for protection. Some Oracle product using websites (including Oracle VM Manager) are still using this!
SQL> alter database force logging;
ORA-12920: database is already in force logging mode
Error in Dutch:
ORA-12920: Database staat al
niet in de force logging-modus.
The word ‘niet’ should not be there!
I’m talking about the ‘third’ field in the database entries. Field number three. Which indicates there could be a fourth, fifth etc… right?
A customer where I came (who went from AIX to Linux), who had interpreted this comment and therefore expanded the oratab with an extra column, to datapump the database (y/n).
When I shut down the databases, there was some unexpected behaviour when I invoked dbshut… Strange, but the extra (last) field ‘for datapump’ was read, not the third!
I had a virtual machine in VirtualBox for an OracleVM Server to test an OracleVM setup, but it froze every 5 minutes and had to restart the OVS again and again.
I got this tip from Robert Pastijn, Oracle Netherlands; When you create a virtual machine in VirtualBox for OracleVM Server, do _not_ choose the ‘Intel PRO’ type adapter type, but the ‘PCnet-FAST‘ one!
There is a bug in Red Hat Linux 6 and Oracle Enterprise Linux 6 (UEK and RHEL-kernel) and probably all other Red Hat 6 related Linux Distro’s.
When you need more memory for SGA/PGA when using MEMORY_MAX_TARGET, you need to resize /dev/shm. By default this is 50% of total memory and Oracle tells you to add the following to /etc/fstab:
shmfs /dev/shm tmpfs size=3g 0 0
Which works… Continue reading
A couple of days ago I did a new install of the Oracle Database Software (on a Virtual Machine) and it kept failing. I got some oracle.cluster.verification.VerificationException error, but I could not get more information from the logs. Usually it’s a bit more detailed after the colon, but this time it just said: [hostname]: [hostname]. Continue reading