I am one of those people who function better by writing things down. One day, I realized that most of my notes don’t have to be private, so here they are - my second brain. Be warned that, if you stumble upon something here that doesn’t make sense to you, it isn’t meant to!
Here is my attempt to design a system for a tiny URL service.
I should practice all the system design questions from that PDF. That includes going through the material once, presenting it to the camera, analyzing the recordings and revising the content after a few days. Should quickly do all of them. The questions shouldn’t be too hard. TBD ETA and I should strive to finish be then. Next step is to do mock interviews. Aim to do both system design and behavioral.
MD5 hashes and UUIDs are 128 bits. So, if you encode them using hexadecimals, each hex character will encode 4 bits of information, so resultant “string” will be 128/4=32 character/bytes long. If you store UUIDs as string, you need 4 additional characters for the hyphens. If you store them in binary format, you just need 128/8 = 16 bytes because each byte will encode 8 bits of information.
Architects should question axioms from the past - the software world changes fast and some of those axioms may no longer be true. Hopefully, the book will give examples. In the past, I used to worry about not knowing non-AWS (for example, Kubernetes) or older technologies deeply enough. That’s actually okay. I don’t have anything more because I’ve dropped the book for now.
Until end of April, I won’t use my phone in the following situations: Restaurants, shops, malls, hikes or other external activities. (Only exception is when I am expecting a phone call from my parents.) Meal time. In bed. (Get alarm clock from parents and use that instead. Leave phone outside the bedroom, if possible.)
See this Also, if you want to print some part of your file, make sure that the starting page number is odd, otherwise you’ll get wrong results.
The following seem to be good: https://faxzero.com/ https://www.gotfreefax.com/
Traefik through Docker Compose seems to be a much cleaner way than manually installing and configuring Nginx, like I used to do earlier. traefik.yaml: entryPoints: web: address: ":80" http: redirections: entryPoint: to: websecure websecure: address: ":443" providers: docker: {} certificatesResolvers: myresolver: acme: email: [email protected] storage: /data/letsencrypt.json httpChallenge: entryPoint: web And docker-compose should contain something like the following: services: traefik: image: traefik:v2.5 # TODO: try with "latest" instead of "2.5". restart: unless-stopped ports: - "80:80" - "443:443" volumes: - "./traefik.yaml:/etc/traefik/traefik.yaml" - "./traefik/data:/data" - "/var/run/docker.sock:/var/run/docker.sock" some-web-service-that-needs-a-reverse-proxy: # ... labels: - "traefik.http.routers.photoprism.rule=Host(`example.com`)" - "traefik.http.routers.photoprism.tls=true" - "traefik.http.routers.photoprism.tls.certresolver=myresolver"
EBS seems to implement chain replication with just 2 copies. How does it recover if one of those servers died? EBS volumes aren’t meant to be shared. While obvious once stated, I imagine this leads to some interesting design trade offs for EBS. Problems with EBS if used for a DB: Too much network IO. Both replicas are stored in same AZ, so no AZ failure resiliency. How to use a relational DB in cloud? One way is to just install it on EC2 with EBS. However, since EBS is a zonal service, the arrangement isn’t resilient to AZ failures. You could do RDS style: replicate the DB in 2 (or more?) AZs and the service manages the replication on customer behalf. However, MySQL writes pages of btree which are large (think 8 KB) and, therefore, slow. (It also writes entries to its write ahead log but those are small and unavoidable.) Quorums: ...
The Digital Minimalism book reminded me today that solitude is an important part of life. (Somewhat ironically, I was driving my car while listening to the book.) I do a good job in decreasing phone usage in my life, or at least I think a lot about doing so. However, the other aspect I don’t do a good job on is this: The author defines solitude as time when your mind is left alone and doesn’t interact with that of others. So, reading books or listening to music doesn’t count. With that definition, I am hardly alone because I am dealing with something or the other - books, music albums or some courses - all the time. ...