If the ZFS ARC goes nuts with e.g. lots of arc_prune processes, try this:
# echo 3 > /proc/sys/vm/drop_caches
Thanks to Xe on #lobsters.
Category Archives: Sys Admin
How to check which process is causing IO wait
The ‘wa’ state in `top` can indicate an IO wait, but to figure out what’s causing the IO wait try this command:
# ps aux | awk '$8 ~ /D/ { print $0 }' | less
You can read more here. Thanks to bsandro on #lobsters.
According to `man top`:
The status of the task can be one of: D = uninterruptible sleep I = idle R = running S = sleeping T = stopped by job control signal t = stopped by debugger during trace Z = zombie
MacBook Pro Retina resolution
So my mate CK put me onto RDM which you can use to improve the graphical resolution on your MacBook Pro Retina display. So much better.
MTU 1492
This NBN Modem Routers ISP Settings says Dodo settings are:
Protocol: PPPoE VLAN ID: 100 MTU: auto or 1492 login: Dodo provided username/password RSP Supplied equipment auto configures
Good to know!
SSL Server Test
Today I came across: SSL Server Test.
Autonomic computing
Found some interesting reading on autonomic computing.
Install Docker Engine on Ubuntu
Reading about how to Install Docker Engine on Ubuntu. I suppose it’s about time.
-------------------
Thu Nov 11 20:38:18 [bash:5.0.17 jobs:0 error:0]
root@tact:/home/jj5
# docker run hello-world
Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
2db29710123e: Pull complete
Digest: sha256:cc15c5b292d8525effc0f89cb299f1804f3a725c8d05e158653a563f15e4f685
Status: Downloaded newer image for hello-world:latest
Hello from Docker!
This message shows that your installation appears to be working correctly.
To generate this message, Docker took the following steps:
1. The Docker client contacted the Docker daemon.
2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
(amd64)
3. The Docker daemon created a new container from that image which runs the
executable that produces the output you are currently reading.
4. The Docker daemon streamed that output to the Docker client, which sent it
to your terminal.
To try something more ambitious, you can run an Ubuntu container with:
$ docker run -it ubuntu bash
Share images, automate workflows, and more with a free Docker ID:
https://hub.docker.com/
For more examples and ideas, visit:
https://docs.docker.com/get-started/
InfoWorld articles
Today I discovered InfoWorld with these articles:
- Complexity is killing software developers
- Why you should use a microservice architecture
- No one wants to manage Kubernetes anymore
And a bonus article from Spotify: How We Use Golden Paths to Solve Fragmentation in Our Software Ecosystem .
Also, I should note, I very much like the InfoWorld URL format: https://www.infoworld.com/article/3614850/no-one-wants-to-manage-kubernetes-anymore.html — this is the same URL structure I use in my own designs.
Fastmail status
I came across this today and thought it was a good example of a service availability reporting system: www.fastmailstatus.com.
dovecot IMAP not working on iOS because of Let’s Encrypt certificate problem
So I was having an issue with the mail app in my iPhones not being able to get IMAP email from my dovecot server.
Turned out I needed to change my dovecot config from this:
ssl_key = </etc/dovecot/mail.{{ domain }}.key
ssl_cert = </etc/dovecot/mail.{{ domain }}.crt
ssl_ca = </etc/dovecot/mail.{{ domain }}.chain.pem
to this:
ssl_key = </etc/dovecot/mail.{{ domain }}.key
ssl_cert = </etc/dovecot/mail.{{ domain }}.chain.pem