HA jargon survival 101


Hi! Finally in the mood to post something not so “technical”. This round, I have met people who got “smoked” by people who speaks technical jargons that makes it hard to access technical competency, so I come up with a short HA jargon survival

Here goes…

Scalability is (From wikipedia)

Screen Shot 2015-03-19 at 11.51.08 PM


Yes, so when people says so-and-so system can scale up or down, it means it doesn’t matter if 100 users or 100K users use the system. the profit margin is more or less the same, and the user experience is more or less no difference

Scalability is NOT

  • Reliability. Saying Scalability is reliability is like saying I can pass IPPT whether my weight is 60KG or 90KG. You know it is not true. If your system is buggy for one user, it will be buggy for 100 users
  • High Availability. As said, if i expand 60KG to 90KG, I may not be able to run as fast, so i can’t be available for you.

Sharding is partitioning of data into smaller, faster, more easily partitioned chunks of data out of a whole. Sharding is an important component of Scalability, as it helps to systems to allocate resources horizontally

Sharding is NOT

  • Replication. People always mixed up the two. If Voldemort can replicate his horcruxes, maybe he would truly achieve immorality. When the data of one of the shard is lost, it is gone forever if not replicated.


Replication is the copy of data into several different data storage. It helps to ensure High Availability by storing data at different places, so if outage happens at one place, it can be recovered

Replication is NOT

  • Backup. True to some extend people mix up both of them because people though storing data in a different place is like backup. It is like I keep extra money under the pillows for emergency use, but replication involves real time MIRRORING of data. What happens when the master data gets corrupted? Yes, the replica gets corrupted as well. So (hot) backup is replication without the real time data mirroring. Backup has some time lag, even if it is one second


Auto Scaling is to add additional servers to the load balancers to handle additional traffic.

Auto Scaling is not

  • Associated to database. Data GROWS with time. Your data don’t shrink when your users dropped off from your products. It is true that I can loose weight from 90KG to 60KG, but I can’t loose my age from 33 to 18. So if somebody says that he/she can set up a DB with autoscale capability, that person is a hoax

That is for today folks. Tech stuff are normally quite serious but this is my first serious attempt to add humour into geek stuff. Hope you guys like it




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