Baptiste Mille-Mathias's questions

I'm writing a script to backup each mysql databases separately on from a mysql server, but instead of handling this inside the script I would like to rely on systemd to generate a backup job to get all the benefits from systemd (I/O, nice, cgroups).

The script, which would be itself triggered by a systemd timer would list all databases and for each of them launch / create a systemd task for for the current day only.

Is there a command that permit to create systemd ad-hoc task ? it could be a binary but as I plan to write a python script I'm interested to know if some python library would allow this.

best

While I'm using Ansible for quite some time, I'm not sure I really understand the differences between a variable and a fact. Could someone explain me, possibly with an example where it really make a difference ?

In openshift 4.x, you have an API for project which seems to be totally similar to namespace in the sense that when you create a project there a namespace created and the other way around. I know namespace is a standard object in kubernetes and project is specific to Openshift. So what does project brings ?

# list projects
oc get projects                                                      
NAME                                                    DISPLAY NAME   STATUS
default                                                                Active
kube-node-lease                                                        Active
kube-public                                                            Active
kube-system                                                            Active
local-storage                                                          Active
openshift                                                              Active
openshift-apiserver                                                    Active

# list namespaces
$ oc get ns
NAME                                                    STATUS   AGE
default                                                 Active   17d
kube-node-lease                                         Active   17d
kube-public                                             Active   17d
kube-system                                             Active   17d
local-storage                                           Active   16d
openshift                                               Active   17d
openshift-apiserver                                     Active   17d
openshift-apiserver-operator                            Active   17d

The list is the same except different columns

oc get project foo
Error from server (NotFound): namespaces "foo" not found
oc get ns foo
Error from server (NotFound): namespaces "foo" not found

15:30 $ oc new-project foo                          
Now using project "foo" on server "https://api.goo.tadadidou.bo:6443".
...       
$ oc get project foo
NAME   DISPLAY NAME   STATUS
foo                   Active
$ oc get ns foo
NAME   STATUS   AGE
foo    Active   70s

Even the yaml output is similar, except the value of the field Kind: which is either Project or Namespace.

I have a bug on some servers where LACP (802.3ad) is not working. I have on all servers a bonding device bond0 with two eth slaves and each interface is plugged on a different swich, and both switches configured with LACP.

Everything seems to be ok, but a network engineer detected some MLAG (Arista LACP implementation) was not working while the physical devices were up.

When I looked to /proc/net/bonding/bond0 of affected servers, I found each interface has a different Aggregator ID. On nominal servers the Aggregator ID is the same.

The issue can be reproduced by switching off and on the port on the switch, then we can observe despite physical link is up, MLAG is down. The bug is present on RHEL 6 and 7 (but not all servers are affected).

Configuration

#/etc/sysconfig/network-scripts/ifcfg-bond0
DEVICE=bond0
MACADDR=14:02:ec:44:e9:80
IPADDR=xxx.xxx.xxx.xxx
NETMASK=xxx.xxx.xxx.xxx
BONDING_OPTS="mode=802.3ad lacp_rate=slow xmit_hash_policy=layer3+4"
BOOTPROTO=none
ONBOOT=yes
USERCTL=no
NM_CONTROLLED=no
PEERDNS=no

# /etc/sysconfig/network-scripts/ifcfg-eno49 (same for other interface)
HWADDR=14:02:ec:44:e9:80
MASTER=bond0
SLAVE=yes
BOOTPROTO=none
ONBOOT=yes
USERCTL=no
NM_CONTROLLED=no
PEERDNS=no

We have a workaround now - set down and up eth interface on server - but this is not ideal.

To check LACP protocol, I did

tcpdump -i eno49 -tt -vv -nnn ether host 01:80:c2:00:00:02

I can see a packet every 30 seconds on one interface but on the other I see a packet every 1 second as is it was trying to establish LACP session.

Do you have a way to troubleshoot and fix that ?

(sorry if I did not use the right term for network I'm not really skilled in LACP)

Thanks

What are their purpose as they have the same content ?

[me@myserver ~]$ cat /etc/issue
Red Hat Enterprise Linux Server release 6.10 (Santiago)
Kernel \r on an \m

[me@myserver ~]$ cat /etc/issue.net
Red Hat Enterprise Linux Server release 6.10 (Santiago)
Kernel \r on an \m

I want to load the be2net module with the parameter rx_frag_size set to 4096, the default value being 2048. As specified by the documentation I created a file /etc/modprobe.d/be2net.conf with the content options be2net rx_frag_size=4096.

However after the reboot, the rx_frag_size is still set to 2048 (checked with command cat /sys/module/be2net/parameters/rx_frag_size).

I tried to find any script that would modprobe be2net in /etc/ without success.

I also tried this method and put an executable script /etc/sysconfig/modules/be2net.modules to load the module using modprobe be2net rx_frag_size=4096 and did not work either, the parameter remains at 2048.

As last method, to verify if the file /etc/modprobe.d/be2net.conf is used by modprobe, I unloaded the module be2net and reloaded it using

modprobe -r be2net
modprobe be2net
cat /sys/module/be2net/parameters/rx_frag_size
4096

so actually it works but this is not persistent.

Do you have any idea what would cause the module not being loaded with the parameter set in /etc/modprobe.d/be2net.conf at boot?

thanks

I've defined some parameters to file /usr/lib/jvm/jre-8-oracle-x64/lib/security/java.security to comply JAVA security settings with our security policy. Some parameter I have edited are

security.overridePropertiesFile=false
jdk.tls.disabledAlgorithms= ...
jdk.certpath.disabledAlgorithms=MD2,...

It is unclear to me if a developer could set custom parameter in an application, does the JVM enforce these parameters or can they be overridden ?

I've seen there this question already about Java security Policy but I'm my case I just want the system-policy to be applied.