Amazon 又把一個大部門的 Oracle 系統轉移到了 AWS 自家的系統

算是 AWS 的 PR 稿,在老闆對雲的宣示與政治正確下本來就會陸陸續續轉過去...

這次是 Amazon 的 Consumer Business 從 Oracle 的系統換到 AWS 自己的系統:「Migration Complete – Amazon’s Consumer Business Just Turned off its Final Oracle Database」。

原先有 75 PB 的資料與 7500 個 database:

We migrated 75 petabytes of internal data stored in nearly 7,500 Oracle databases to multiple AWS database services including Amazon DynamoDB, Amazon Aurora, Amazon Relational Database Service (RDS), and Amazon Redshift.

其中一個優點是省成本,但是也投入了超過一百個團隊一起參與轉移,會需要攤多久才會打平,這點在沒有看到內部財務資料其實沒辦法判斷,而且工程資源的稀缺性也是個沒有被看到的資訊:

Cost Reduction – We reduced our database costs by over 60% on top of the heavily discounted rate we negotiated based on our scale. Customers regularly report cost savings of 90% by switching from Oracle to AWS.

More than 100 teams in Amazon’s Consumer business participated in the migration effort.

然後 latency 的下降其實也只能參考,因為轉移系統的時候也會順便改寫,有多少是因為 AWS 服務本身帶出來,在沒有內部資料看不出來:

Performance Improvements – Latency of our consumer-facing applications was reduced by 40%.

管理成本算是裡面唯一可以參考的,畢竟是搬到可延展擴充的服務:

Administrative Overhead – The switch to managed services reduced database admin overhead by 70%.

另外,沒寫的東西比較有趣,像是他們沒有選擇 Athena 而是用 Redshift,看起來像是先轉上去,其他找機會再說...

AWS Cloud 的用法

Hacker News Daily 上看到這則,分享了 AWS (他的前東家,超過八年) 的使用經驗:

除了可以在 Twitter 上看以外,也可以用 Thread reader 直接讀整條 thread,應該也還算清楚:「This is how I use the good parts of @awscloud, while filtering out all the distracting hype.」。

這邊的經驗談主要是在 web 與 app 相關的服務這塊:

有講到 AWS 的業務其實圍繞在 scalability 上發展,但這對 startup 可能反而是扣分,因為暴力法解反而可以大幅簡化架構換得 agile (而讓 startup 存活下來)。

另外從團隊的開發成本來看,這些 scale 的技術增加了開發成本,產生了很多開發上的限制,這些觀點也有點帶到「Premature optimization is the root of all evil」在講的事情:

最後的結論可以看到一些列表:

除了 DynamoDB 的意見不同外 (這邊提到的 DDB),其他的我都可以接受...

RDS 支援 Storage Auto Scaling

Amazon RDS 推出了 Storage Auto Scaling:「Amazon RDS now supports Storage Auto Scaling」。

看起來傳統 RDBMS 類的都支援 (也就是非 Aurora 的這些):

Starting today, Amazon RDS for MariaDB, Amazon RDS for MySQL, Amazon RDS for PostgreSQL, Amazon RDS for SQL Server and Amazon RDS for Oracle support RDS Storage Auto Scaling.

仔細看了一下新聞稿,裡面都只有提到 scale up,沒有提到 scale down,這個功能應該是只會提昇不會下降,所以要注意突然用很多空間,再砍掉後的問題:

RDS Storage Auto Scaling automatically scales storage capacity in response to growing database workloads, with zero downtime.

RDS Storage Auto Scaling continuously monitors actual storage consumption, and scales capacity up automatically when actual utilization approaches provisioned storage capacity.

除了香港外的所有商業區域都提供:

RDS Storage Auto Scaling is available in all commercial AWS regions except in Asia Pacific (Hong Kong) and AWS GovCloud.

Amazon Aurora with MySQL 5.7 支援 GTID

雖然在 AWS 上服務的 HA 大多都不需要自己管理,但備份機制 (甚至異地備援) 還是要自己規劃,Amazon Aurora with MySQL 的 GTID 功能算是讓這塊多了一個選擇:「Amazon Aurora with MySQL 5.7 Compatibility Supports GTID-Based Replication」。

公告裡面有提到 Aurora 自己的 replication 還是用自己的機制,而非透過 GTID 做的:

This provides complete consistency when using binlog replication between an Aurora database and an external MySQL database. Your replication won’t miss transactions or generate conflicts, even after failover or downtime. (Note that replication within an Aurora cluster doesn't use binlog files, so the GTID feature doesn't apply.)

不過就 Aurora 的架構來說,整個 cluster 比較像是看作一個整體,用 binlog + position 應該是夠用的?也不會有 failover 時的 conflict 問題?不確定用 GTID 的好處會在哪邊,還得再想看看...

Amazon Aurora Global Database

AWSAurora (MySQL) 推出 Amazon Aurora Global Database:「Announcing Amazon Aurora Global Database」。

看起來不是 multi-master (從 secondary region 這個字看),所以寫入的部分還是得送回 primary region 處理:

Aurora Global Database uses storage-based replication with typical latency of less than 1 second, using dedicated infrastructure that leaves your database fully available to serve application workloads. In the unlikely event of a regional degradation or outage, one of the secondary regions can be promoted to full read/write capabilities in less than 1 minute.

應該是單一 endpoint 幫你處理這些雜事...

Amazon Lightsail 也把 RDS 拿出來賣了...

RDS (MySQL) 也被 Amazon Lightsail 包裝出來賣了:「New – Managed Databases for Amazon Lightsail」。

目前支援 MySQL 5.6 與 MySQL 5.7:

We are launching with support for MySQL 5.6 and 5.7, and will add support for PostgreSQL 9.6 and 10 very soon.

然後規格與價位,其中頻寬費用是指不同區時的頻寬 (同一區內的不計費):

Data Transfer – Data transfer to and from Lightsail instances in the same AWS Region does not count against the usage that is included in your plan.

這個服務應該是目前其他 VPS 沒提供的,這樣可以預期其他 VPS 應該也會被迫推出類似的服務?然後 AWS 也會再搬其他的服務出來賣?

Amazon Aurora 支援 Parallel Query 加速

Amazon Aurora 推出了 Parallel Query,可以加速計算速度:「New – Parallel Query for Amazon Aurora」。原理是利用 Aurora 把 storage 層打散的前提,所以有機會透過螞蟻雄兵處理:

官方給的範例可以連到原文去看,可以看到有打開 aurora_pq 與沒打開的效能差異:

15 rows in set (1 min 53.36 sec)
15 rows in set (1 hour 25 min 51.89 sec)

打開後大約是原來的 1/45 時間,提昇超多...

不過還是有些限制,我最在意的就是目前只支援相容於 MySQL 5.6 的版本 (居然不是先支援 5.7):

Engine Support – We are launching with support for MySQL 5.6, and are working on support for MySQL 5.7 and PostgreSQL.

然後沒有多餘費用,只是 i/o cost 可能會增加:

Cost – You can make use of Parallel Query at no extra charge. However, because it makes direct access to storage, there is a possibility that your IO cost will increase.

Aurora Serverless MySQL 進入 GA

AWS 宣佈能 auto-scale 的 Aurora Serverless MySQL 進入 GA:「Aurora Serverless MySQL Generally Available」:

不過目前開放的區域有限:

Aurora Serverless for Aurora MySQL is available now in US East (N. Virginia), US East (Ohio), US West (Oregon), Europe (Ireland).

以秒計費,但低消是 5 分鐘:

You pay a flat rate per second of ACU usage, with a minimum of 5 minutes of usage each time the database is activated.

us-east-1 的價錢來看,每個 ACU 是 USD$0.06/hour,而每個 ACU 大約是 standard instance 的價錢:

1 ACU has approximately 2 GB of memory with corresponding CPU and networking, similar to what is used in Aurora Standard instances.

但這沒看懂,是 db.t2.small 還是 db.t2.medium?另外比較是全速還是 small 的 20% 或 medium 的 40%?這部份也許還要再問看看才知道...

storage 與 I/O 的費用則是相同,倒是不用比較這塊... 再來不知道有沒有推出 Reserved ACU 的計畫,光是一年付清就差蠻多的。

要不要換過去其實還是要看看使用的量,以及可以接受的成本來決定...

從 Aurora 同步到 EC2 上的 MySQL

Percona 這篇「How to Set Up Replication Between AWS Aurora and an External MySQL Instance」講怎麼設定 Amazon Aurora,把資料同步到外部的 MySQL instance。

其中最重要的應該是你需要透過 snapshot 建出 consistent backup,然後用這份資料去接 Aurora 的 master server:

Create a snapshot and restore it (create a new instance from a snapshot). This is only needed to make a consistent copy with mysqldump. As Aurora does not allow “super” privileges, running mysqldump --master-data is not possible. The snapshot is the only way to get a consistent backup with the specific binary log position.

能拉出來後續就能做很多事情...

MySQL 版本的 Amazon Aurora 會將各種記錄丟到 CloudWatch Logs 了...

剛好今天才被問是不是可以在 Amazon Aurora (MySQL-Compatible Edition) 裡面翻出有哪些 Slow Query,剛好想到這幾天發表了這個功能:「Amazon Aurora Publishes General, Slow Query and Error Logs to Amazon CloudWatch」。

You can now configure the MySQL-compatible edition of Amazon Aurora to publish general logs, slow query logs, and error logs to Amazon CloudWatch Logs. Previously, you could only publish audit logs.

看起來是要另外開 (畢竟 CloudWatch Logs 不是免費的 XD),不過以這類型的 log 產生速度與數量來說應該還行...