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Alibaba Cloud, Pick the right instance type

When we first tried to launch our first instance on Alibaba Cloud, intuitively we picked the default burstable type T5. Once launched, we are shocked, by the speed of running a simple apt-get update, how can it be so slow, it took 2 minutes for it to be completed. Kept exploring and found this instance type: The cost is slightly…

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加密货币Cryptocurrency,是怎么一回事?

作者背景: 因为在IT行业的缘故,我第一次接触比特币(Bitcoin)大概是在2010~2011年左右,当时1个Bitcoin价格大概低于USD1。 当时觉得新奇好玩,也曾近做过miner,因为只需要开着电脑就能赚Bitcoin。 但是很快就厌倦了,因为对于此技术似懂非懂,在本地(马来西亚),当时Bitcoin也无用武之处,很快的就把整个Bitcoin抛诸脑后。 一直到近一两年,Bitcoin已经无人不晓,但大部分人都抱着观看、怀疑的态度。相信Bitcoin的人却非常狂热的把钱投进Bitcoin及Altcoin里。 其实作者是倾向于前者的,但是Blockhain贵为能够改变世界的新技术,身为科技人的我们一定要搞清楚这门技术。于是在网上看了很多资料,但是现有的资料大多都是以投资(投机)赚钱,而且以英文为主,有些技术名称甚至IT人都不明白,何况是普通人。 所以作者决定在Research同时,把资料记录下来,同时以比较擅长的中文来写,希望更多的人可以了解。     首先,大家要先来认识专用名词 Blockchain – 区块链 Cryptocurrency – 加密货币/电子货币 Bitcoin – 比特币 Ethereum – 以台币 Altcoin – 比特币以外的币(coin),统称Altcoin (Alternative Coin) ICO – Initial Coin Offering – 首次募货币,类似公司上市IPO Mining – 挖矿,实际上是一种电脑程式算法,以确保没有人可以作弊 Proof of Work – 工作量证明 – 目前的Blockchain都以这两种形式运作,以后会加以解释 Proof of Stake – 权益证明 -目前的Blockchain都以这两种形式运作,以后会加以解释 Genesis Block     做为第一篇文章,就先从为何次技术诞生说起吧。(以作者所了解所写出,如果有误请点出) 最初大概在2008年金融海啸时,当时很多人对现有的金融系统产生了怀疑,结果2009年Satoshi Nakamoto就开发出了Bitcoin,把它开源免费放在网上。 到现在为止,没有人知道Satoshi Nakamoto这个人真正是谁,它也很有可能是一个组织。而根据Bitcoin的Blockhain数据查回,这个创始人/组织依然拥有980,000个Bitcoin。   传统的资料储存资料方式,就是把资料存在数据库中,而这些数据库主人能够随时进入或甚至更改。 现有的金融系统就是最佳的列子,人们需要透过银行做交易,把所有资料存进银行的数据库,然后100%服从银行的决定。以技术层面来看,银行里的资料是能被串改的,但人们只能服从。…

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Letsencrypt failed to renew

We were getting this letsencrypt renewal error on some Ubuntu 16.04 machines: OSError: Command /opt/eff.org/certbot/venv/bin/python2.7 – setuptools pkg_resources pip wheel failed with error code 1 Googling around, hit a few walls and finally found the solution, just need to run this in Ubuntu: export LC_ALL=”en_US.UTF-8″ export LC_CTYPE=”en_US.UTF-8″ Then continue on with the letsencrypt-auto script will do.

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Ubuntu run out of space?

If you are getting ‘running out of space’ from your SSH console, but running a df -h shows that there are still plenty of free space left, then most likely inode is the one that run out. To confirm it, just run the command df -i from the result you should be able to a 100% in the mount point, for…

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Scaling PHP CMS in AWS

There’s two major challenge when scaling a traditional CMS like Prestashop / Drupal: – Centralized session – File storage synchronized – Isolate Backend traffic to a single instance Let’s dive into details for each of them:   Centralized Session This is the easiest one to be taken care of, we will use Redis as the session backend, in AWS, the…

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Laratalks #7 – All about A.I.

When comes to Artificial Intelligence, PHP programming language would never cross most programmer’s mind. So happen there is a PHP community called Laravens. They were founded around 6 months ago and organize monthly gathering called Laratalks. Each time they will invite guests from the industry to share cool knowledge among the community. July Laratalks’ topic was about A.I.. When this event…

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Cloud – From Freedom to Jail, then back to Freedom

Freedom and flexibility are the main reasons people move to cloud, especially when there are tools like AWS RDBMS. They allow you to move to cloud and freed from your current on-premise vendor. With a BONUS! They also provide the tool that can help you to convert your database from one platform to another, FREEDOM!!! But without realizing it, we are merely…

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Cloud – Who stolen my vCPU ?

As discussed in previous posts like public vs private cloud, you are getting vCPU for your public cloud servers, which is shared among other VMs in the same hypervisor. But how do you know if the hypervisor,  the physical hardware CPU itself is being overpopulated? What you need to do is: SSH to your server Run the top command: type top…

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Public cloud and Private cloud

What’s the difference between Public and Private The only main difference between the two is simple: Using public cloud: Sharing the physical hardware with other user Using private cloud: All the VM is sitting on your dedicated servers, sharing resource with no others but your own VM A wider definition of ‘Cloud’ itself could simply be – Offsite infrastructure /…

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Scaling on the Cloud – How and When ? Part 2

We have discussed about the HOW of scaling in Part 1, let’s discuss on the WHEN of scaling. 1. Preemptive Scaling In other words, manual scaling. You are expecting an increase of traffic like: A crazy product promotion with huge discount on your e-commerce site Marketing spending to draw huge traffic, such as LINE events, Facebook campaigns, etc. Your guts…

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