Java: Slow java with server.policy enabled – how to fix this issue

If you use Java security manager for hardening your java processes, you have to add the following JVM options:
-Djava.security.manager
-Djava.security.policy=server.policy 
Create a server.policy file (you can use jdkXXX/jre/lib/security/java.policy as a tamplate) and add the following line:
permission java.net.SocketPermission "localhost:*", "listen, accept, connect, resolve"; 
Now create a small java program, which listens on a port (like this example).

If you send a message with netcat
(more...)

Resolving Slow Performance, Skipped Checks and Timeouts on Exa Check (exachk)

Background

For more information with regards to Exa Check, please read the following post:
How to use Oracle Exadata Database Machine Exa Check (exachk)

Slow Performance, Skipped Checks and Timeouts

When running the latest exachk (at time of writing, version 18.3.0_20180808), you may notice it takes a long time to run compared to the past.  This is due to the vast amount of additional checks carried out by the tool.  Due to (more...)

Repairing a Linux host with disk/filesystem issues

This is a writeup on some scenario’s for disk issues that you could encounter when running linux systems. The linux systems I am talking about are centos/redhat/oracle (EL) version 7 systems. This is just a writeup for myself to know how to deal with different scenario’s, hopefully other people find this interesting too. I don’t believe there is any difference for the below scenario’s and resolutions between running physical/bare metal, virtualised or in the cloud, (more...)

Linux: journalctl and systemd – better than /var/log/messages?

Nearly 8 years ago systemd was introduced on some Linux distribution (s. here). Last week i discovered some helpful commands, which i share with you.

If you want to take a look at kernel message (for example system boot), you command is
dmesg
The new equivalent is
journalctl -k
Ok - not really amazing.
But all of you know the message
See "systemctl status nginx.service" and "journalctl -xe" for details.
You can run (more...)

Missing directory in /var/run or /run – tmpfiles.d

Sometimes is happens, that an application/demon refuses to start because of missing files/directories in /var/run.
The first solution is:
  • Create the directory in /var/run
  • Change the permissions
and everything is fine.

Not really.

After the next reboot, the directory is missing again and you have to go for the "first" solution again.

The right solution works like this:
Inside /usr/lib/tmpfiles.d create a myexample.conf file with this content:
        d /var/run/myexample  (more...)

Extending the root LVM Partition on Exadata

On an Oracle Exadata Database Machine, the ‘/’ (root) is defaulted to a size of 30Gb, which can easily fill up.  Luckily this is just a Logical Volume and there’s normally lots of space available on the Logical Volume Group which is usually untapped.

Extending ‘/’

Identify how much space is used and free on ‘/’ using df:

[root@v1ex1dbadm01 ~]# df -h /
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VGExaDb-LVDbSys1
                       30G   22G   (more...)

Oracle Database Backup Service Fails with: ORA-19511: – KBHS-00715: HTTP error occurred ‘oracle-error’ – ORA-29024

I discovered an Oracle Cloud Database Backup failing with:

Starting backup at 2018/09/08 20:00:04
current log archived
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup plus archivelog command at 09/08/2018 20:00:07
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27023: skgfqsbi: media manager protocol error
ORA-19511: non RMAN, but media manager or vendor specific failure, error text:
   KBHS-00715: HTTP error occurred 'oracle-error'
KBHS-00712: ORA-29024  (more...)

Docker on Oracle Linux

It occurred to me that if you want to start using Docker there are plenty examples that use Ubuntu as a base platform. I read a book called Learning Docker that assumes Ubuntu for the examples. I know I am quite stubborn, a "know-it-better" person, but I want to be able to do the same on Oracle Linux.

Docker on Oracle Linux turns out not too complicated. But I ran in to a caveat that (more...)

systemd: systemd-notify not working for non-root-users

Sometimes you have to write your own startup scripts. Recent linux distributions require systemd scripts. This is not really a problem except you have to fulfill the following requirements:
  • Run the service as a non-root-user
  • The service has a startup phase and you want to start the next startup scripts after this startup phase
So the systemd-script has to look like this:
# cat /lib/systemd/system/TEST.service
[Unit]
Description=MyTestSystemdConfiguration

[Service]
User=schroff
Type=notify
ExecStart=/home/schroff/bin/test.sh
NotifyAccess=all
The (more...)

Ubuntu / Linux: WLAN connections fails with "denied authentication (status 17)"

During holidays i was not able to connect my laptop to the WLAN.
The /var/log/syslog showed the following:
Jul 15 13:45:20 pc wpa_supplicant[935]: wlp3s0: SME: Trying to authenticate with 14:9d:09:fe:a4:b3 (SSID='HUAWEI BTV' freq=2437 MHz)
Jul 15 13:45:20 pc kernel: [ 6972.826888] wlp3s0: authenticate with 14:9d:09:fe:a4:b3
Jul 15 13:45:20 pc NetworkManager[797]:   [1531655120.4746] device (wlp3s0): supplicant interface state: disconnected -> authenticating
Jul 15 13:45:20 pc kernel: [ 6972.829942] wlp3s0: send auth to 14:9d:09:fe:a4:b3 (more...)

Oracle Database 18c: Documentation released!

Today i surfed to docs.oracle.com and there i found the documentation for oracle database 18c:


In march 2018 i wrote about the new installation procedure of oracle database 18c via rpm, which was announced inside the "new features".

The installation guide for Linux contains now the commands for installing the database via rpm. Here a screencopy of chapter 11:
 rpm -ivh oracle-ee-db-18.1.0.0.0-1.x86_64.rpm
This command creates the (more...)

Ubuntu 16.04: Installation of chrome-browser fails with libnss3 (>= 2:3.22) [2]


The first solution for installing google-chrome after getting the error
dpkg: Abhängigkeitsprobleme verhindern Konfiguration von google-chrome-stable:
 google-chrome-stable hängt ab von libnss3 (>= 2:3.22); aber:
  Version von libnss3:amd64 auf dem System ist 2:3.21-1ubuntu4.

dpkg: Fehler beim Bearbeiten des Paketes google-chrome-stable (--install):
 Abhängigkeitsprobleme - verbleibt unkonfiguriert
was to install chromium (see this posting).

But now i know, what the problem was:
Inside /etc/apt/sources.list the entry:
deb http://security.ubuntu.com/ubuntu/ xenial-security restricted main (more...)

Quick install of prometheus, node_exporter and grafana

This blogpost is a follow up of this blogpost, with the exception that the install method in this blogpost is way easier, it uses an Ansible playbook to do most of the installation.

1. Install git and ansible via EPEL:

# yum -y localinstall https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
# yum -y install ansible git

2. Clone my ‘prometheus_node_exp_grafana_install’ repository:

# git clone https://gitlab.com/FritsHoogland/prometheus_node_exp_grafana_install.git

3. Run the prometheus.yml playbook to install (more...)

Oracle database wait event ‘db file async I/O submit’ timing bug

This blogpost is a look into a bug in the wait interface that has been reported by me to Oracle a few times. I verified all versions from Oracle 11.2 version up to 18.2.0.0.180417 on Linux x86_64, in all these versions this bug is present. The bug is that the wait event ‘db file async I/O submit’ does not time anything when using ASM, only when using a filesystem, where (more...)

Virtualbox: vboxdrv.sh: failed & Run ‘make oldconfig && make prepare’

After updating to ubuntu 18.04 i had to reinstall virtualbox:


# dpkg -i virtualbox-5.2_5.2.10-122088~Debian~stretch_amd64.deb 
Vormals nicht ausgewähltes Paket virtualbox-5.2 wird gewählt.
(Lese Datenbank ... 378316 Dateien und Verzeichnisse sind derzeit installiert.)
Vorbereitung zum Entpacken von virtualbox-5.2_5.2.10-122088~Debian~stretch_amd64.deb ...
Entpacken von virtualbox-5.2 (5.2.10-122088~Debian~stretch) ...
virtualbox-5.2 (5.2.10-122088~Debian~stretch) wird eingerichtet ...
addgroup: Die Gruppe »vboxusers« existiert bereits als Systemgruppe. Programmende.
vboxdrv.sh: failed: Look at /var/log/vbox-install. (more...)

Ubuntu 16.04: Installation of chrome-browser fails with libnss3 (>= 2:3.22)

On my old laptop with ubuntu 16.04 i tried to install "chrome-browser":
# dpkg -i google-chrome-stable_current_amd64\ \(1\).deb 
Vormals nicht ausgewähltes Paket google-chrome-stable wird gewählt.
(Lese Datenbank ... 137351 Dateien und Verzeichnisse sind derzeit installiert.)
Vorbereitung zum Entpacken von google-chrome-stable_current_amd64 (1).deb ...
Entpacken von google-chrome-stable (64.0.3282.186-1) ...
dpkg: Abhängigkeitsprobleme verhindern Konfiguration von google-chrome-stable:
 google-chrome-stable hängt ab von libnss3 (>= 2:3.22); aber:
  Version von libnss3:amd64 auf dem System ist 2:3.21-1ubuntu4.

(more...)

Beware of loopback MTU size with RAC on Oracle Linux 7

I recently had to troubleshoot a hung instance in a 2 node RAC system. 4 months earlier, the system was reinstalled in a rolling fashion due to the requirement of Linux Upgrade from Oracle Linux 5 to Oracle Linux 7. This was required because of lack of certification for a storage migration to an AllFlash Storage. The system has been stable when running with Oracle Linux 5 for several years. Around 4 months after the (more...)

Installing haveged from Oracle repositories

In my previous blog, I mentioned the installation of the utility Haveged that is used to increase your entropy on non-gui systems. Since you can download it from the Oracle yum repository, I figured that I could install it from yum too, instead of using rpm. This prevents me from having to download it myself, and ensures I have the one that is applicable to my version of Linux.

Too bad it isn't (more...)

Base box ready? Let’s create a box!

Last week I wrote about creating our own Vagrant base box, based on the new and fresh Oracle Linux 7 Update 5. As a reaction on my article I got noted that Oracle also keeps base boxes for their latest linuxes at http://yum.oracle.com/boxes. They're also a great start.

To begin, I created a project structure for all my vagrant projects:
As you can see, I have a vagrant main projects folder on my (more...)

Oracle Linux 7.5 released ?!

Oracle released its Linux in version 7.5 without a announcement on their webpages. If you ask google
oracle linux 7.5
you will be directed to this site:

But with the right search string you can find Oracle Linux 7.5 inside edelivery.oracle.com:

The new features can be found here:
or here: