Tag Archives: rds

How to interview an amazon database expert

via GIPHY

Amazon releases a new database offering every other day. It sure isn’t easy to keep up.

Join 35,000 others and follow Sean Hull on twitter @hullsean.

Let’s say you’re hiring a devops & you want to suss out their database knowledge? Or you’re hiring a professional services firm or freelance consultant. Whatever the case you’ll need to sift through for the best people. Here’s how.

Also: How to interview an AWS expert

What database does Amazon support for caching?

Caching is a popular way to speed up access to your backend database. Put Amazon’s elasticache behind your webserver, and you can reduce load on your database by 90%. Nice!

The two types that amazon supports are Memcache & Redis. Memcache is historically more popular. These days Redis seems a clear winner. It’s faster, and can maintain your cached data between restarts. That will save you I promise!

Also: Is AWS too complex for small dev teams?

How can I store big data in AWS?

Amazon’s data warehouse offering is called Redshift. I wrote Why is everyone suddenly talking about Redshift?. Why indeed!

When you’re doing large reports for your business intelligence team, you don’t want to bog down your backend relational database. Redshift is purpose built for this use case.

I’ve see a report that took over 8 hours in MySQL return in under 60 seconds in Redshift!

A new offering is Amazon Spectrum. This tech is super cool. Load up all your data into S3, in standard CSV format. Then without even loading it into Redshift, you can query the S3 data directly. This is super useful. Firstly because S3 is 1/10th the price. But also because it allows you to stage your data before loading into Redshift itself. Goodbye Google Big Query! I talked about spectrum here.

Related: Which engineering roles are in greatest demand?

What relational database options are there on Amazon?

Amazon supports a number of options through it’s Relational Database Service or RDS. This is managed databases, which means less work on your DBAs shoulders. It also may make upgrades slower and harder with more downtime, but you get what you pay for.

There are a lot of platforms available. As you might guess MySQL & Postgres are there. Great! Even better you can use MariaDB if that’s your favorite. You can also go with Aurora which is Amazon’s own home-brew drop in replacement for MySQL that promises greater durability and some speedups.

If you’re a glutton for punishment, you can even get Oracle & SQL Server working on RDS. Very nice!

Read: Can on-demand consulting save startups time & money?

Does AWS have a NoSQL database solution?

If NoSQL is to your taste, Amazon has DynamoDB. According to . I haven’t seen a lot of large production applications using it, but what he describes makes a lot of sense. The way Amazon scales nodes & data I/O is bound to run into real performance problems.

That said it can be a great way to get you up and running quickly.

Read: Can on-demand consulting save startups time & money?

How do I do ETL & migrate data to AWS?

Let’s be honest, Amazon wants to make this really easy. The quicker & simpler it is to get your data there, that more you’ll buy!

Amazon’s Database Migration Service or DMS allows you to configure your old database as a data source, then choose a Amazon db solution as destination, then just turn on the spigot and pump your data in!

ETL is extract transform and load, data warehouse terminology for slicing and dicing data before you load it into your warehouse. Many of todays warehouses are being built with the data lake model, because databases like Redshift have gotten so damn fast. That model means you stage all your source data as-is in your warehouse, then build views & summary tables as needed to speed up queries & reports. Even better you might look a tool like xplenty.

Amazon’s new offering is called Glue. Five ways to get data into Amazon Redshift. This solution is purpose build for creating a powerful data pipeline, complete with python code to do transformations.

Read: Is data your dirty little secret?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don’t work with recruiters

What products & improvements are new on AWS?

Amazon is releasing new products & services to it’s global cloud compute network at a rate that has all of our heads spinning.

Join 32,000 others and follow Sean Hull on twitter @hullsean.

Here’s new stuff worth mentioning around databases & data.

1. For ETL – AWS GLUE

Moving data from your transactional MySQL or Arora database to your reporting database isn’t always easy.

In the past you could use a service like xplenty or Alooma.

Now Amazon themselves are getting into the ETL game, providing a new service called Glue.

Also: RDS or Mysql? 10 use cases

2. Query S3 with Athena

Chances are if you’re using AWS for anything, you’ve got data in S3. And wouldn’t it be nice to pick that apart and dig through it, where it sits?

Oracle had a feature called “external tables” and MySQL had something similar. Now Amazon is offering that native within it’s own cloud universe. Thanks to some tricky lambda code, now you can do that. Don’t worry how they did it, because it’s been packaged into a nice easy service for your use!

Related: When you have to take the fall – consulting war stories

3. Business Intelligence with QuickSight

If you’re a data driven startup, and who isn’t these days, you’re going to have a business unit building reports. Tableau or Looker may be in your wheelhouse.

Amazon is obviously seeing the opportunity here, and competing with their own partners. Check out Amazon Quicksight for details.

Read: Is upgrading RDS like a sh*t storm that will not end?

4. Expanded RDS

RDS is obviously a very popular offering. And even though zero downtime is very hard to achieve with RDS, you’ll save plenty on DBAs and admins you don’t have to hire!

If you hadn’t heard, there is now MariaDB support. And with it, there’s a migration from MySQL to Mariadb as well.

Using Mariadb may bring you performance advantages & improvements. But RDS may mitigate this by productize & standarizing things.

You can also now move encrypted snapshots across regions. In my view this isn’t really a new feature, but rather fixing something that was broken before. The previous limitation was really more a symptom of their global network of data centers, than any built feature per se.

Also: Is the difference between dev & ops a four-letter word?

5. Expanded Redshift

As I’ve blogged before, everybody is excited about Redshift these days.

Amazon has introduced some new features.

o better loading of sorted data

This is done behind the scenes to load data quickly, and keep it stored efficiently. No more vacuuming after a big load!

o user & database rate limiting

Limit connections on a per user or per database level. Useful!

o storage estimates on analyze

When you perform the analyze command, you can get storage information so it’s easier to decide datatypes & compression type. Nifty!

Also: Is Redshift outpacing Hadoop as the big data warehouse for startups?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don’t work with recruiters

5 core pieces of the Amazon Cloud puzzle to get your project off the ground

amazon cloud automation

One of the most common engagements I do is working with firms in and around the NYC startup sector. I evaluate AWS infrastructures & applications built in the Amazon cloud.

Join 32,000 others and follow Sean Hull on twitter @hullsean.

I’ve seen some patterns in customers usage of Amazon. Below is a laundry list of the most important ones.

On our products & pricing page you can see more detail including how we perform a performance review and a sample executive summary.

1. Use automation

When you first start using Amazon Web Services to host your application, you like many before you may think of it like you’re old school hosting. Setup a machine, configure it, get your code running. The traditional model of systems administration. It’s fine for a single server, but if you’re managing a more complex deploy with continuous integration, or want to be resilient to regular server failures you need to do more.

Enter the various automation tools on offer. The simplest of the three is Elastic Beanstalk. If you’re using a very standard stack & don’t need a lot of customizations, this may well work for you.

With more complex deployments you’ll likely want to look at Opsworks Sounds familiar? That’s because it *is* Opscode Chef. Everything you can do with Chef & all the templates out there will work with Amazon’s offering. Let AWS manage your templates & make sure your servers are in the right state, just like hosted chef.

If you want to get down to the assembly language layer of infrastructure in Amazon, you’ll eventually be dealing with CloudFormation. This is JSON code which defines everything, from a server with an attached EBS volume, to a VPC with security rules, IAM users & everything inbetween. It is ultimately what these other services utilize under the hood.

Also: Is Amazon too big to fail?

2. Use Advisor & Alerts

Amazon has a few cool tools to help you manage your infrastructure better. One is called Trusted Advisor . This helps you by looking at your aws usage for best practices. Cost, performance, security & high availability are the big focal points.

In order to make best use of alerts, you’ll want to do a few things. First define an auto scaling group. Even if you don’t want to use autoscaling, putting your instance into one allows amazon to do the monitoring you’ll want.

Next you’ll want to analyze your CloudWatch metrics for usage patterns. Notice a spike, could be a job that is running, or it could be a seasonal traffic spike that you need to manage. Once you have some ideas here, you can set alerts around normal & problematic usage patterns.

Related: Are we fast approaching cloud-mageddon?

3. Use Multi-factor at Login

If you haven’t already done so, you’ll want to enable multi-factor authentication on your AWS account. This provides much more security than a password (even a sufficiently long one) can ever do. You can use Google authenticator to generate the mfa codes and associated it with your smartphone.

While you’re at it, you’ll want to create at least one alternate IAM account so you’re not logging in through the root AWS account. This adds a layer of security to your infrastructure. Consider creating an account for your command line tools to spinup components in the cloud.

You can also use MFA for your command line SSH logins. This is also recommended & not terribly hard to setup.

Read: When hosting data on Amazon turns bloodsport

4. Use virtual networking

Amazon offers Virtual Private Cloud which allows you to create virtual networks within the Amazon cloud. Set your own ip address range, create route tables, gateways, subnets & control security settings.

There is another interesting offering called VPC peering. Previously, if you wanted to route between two VPCs or across the internet to your office network, you’d have to run a box within your VPC to do the networking. This became a single point of failure, and also had to be administered.

With VPC peering, Amazon can do this at the virtualization layer, without extra cost, without single point of failure & without overhead. You can even use VPC peering to network between two AWS accounts. Cool stuff!

Also: Are SQL databases dead?

5. Size instances & I/O

I worked with one startup that had been founded in 2010. They had initially built their infrastructure on AWS so they chose instances based on what was available at the time. Those were m1.large & m1.xlarge. A smart choice at the time, but oh how things evolve in the amazon world.

Now those instance types are “previous generation”. Newer instances offer SSD, more CPU & better I/O for roughly the same price. If you’re in this position, be sure to evaluate upgrading your instances.

If you’re on Amazon RDS, you may not be able to get to the newer instance sizes until you upgrade your database. Does upgrading MySQL involve much more downtime on Amazon RDS? In my experience it surely does.

Along with instance sizes, you’ll also want to evaluate disk I/O options. By default instances in amazon being multi-tenant, use disk as a shared resource. So they’ll see it go up & down dramatically. This can kill database performance & can be painful. There are expensive solutions. Consider looking at provisioned IOPS and additional SSD storage.

Also: Is the difference between dev & ops a four-letter word?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don’t work with recruiters

When hosting data on Amazon turns bloodsport

reddit aws outage

There’s a strong trend to automation across the cloud. That’s a great thing for startups because it reduces operational headaches & lets them focus on building products.

Join 31,000 others and follow Sean Hull on twitter @hullsean.

But as that trend begins to touch the database tier, all sorts of complications emerge. Let’s take a look at some of the tradeoffs.

1. Database as a service trend

I was recently reading Baron Schwartz’s article on the trend to database as a service.

I work with a lot of venture backed startups & pay close attention to what’s happening in New York & SF. From where I’m standing I see a similar trend. As automation simplifies management across the application stack, from load balancers to web & search servers, the same advantages are moving to database management.

Also: How to automate MySQL analysis on Amazon RDS

2. How Amazon RDS helps

Amazon’s RDS offers firms a data solution for Oracle & SQL Server as well as MySQL. For those just starting, it offers a long list of advantages.

o quick push-button deployment in minutes
o standardized parameters settings that just work
o ability to scale up or down from the dashboard
o automated backups
o multi-az so you can sleep at night

This brings a huge advantage to startups. Many have a team of developers but aren’t large enough to need an operations team and can’t afford a dedicated database administrator.

Amazon is obviously helping these firms raise the bar. And that’s a good thing.

Related: RDS or MySQL 10 use cases

3. How Amazon RDS hurts

As you get bigger, your needs will grow too. You’ll have tens of millions of customers, and with more customers comes an even higher bar. Zero downtime becomes critical. It’s then that Amazon’s solution starts to become frustrating.

Unpredictable upgrades

MySQL upgrades on RDS are a messy activity. Amazon will restart the instance, backup the instance, perform the upgrade then restart again. Each of these restarts takes a few minutes. The whole operation may have you down for ten minutes. This becomes more frustrating when your hands are completely tied. You don’t know when or what will happen!

When you roll-your-own instance, an upgrade can be performed in a matter of seconds. No instance restarts are necessary and you can monitor the process to know exactly where you are. This is the kind of control you’re going to want if you have millions of customers relying on your site & uptime.

Unnecessary slow restarts

When you apply parameter changes on RDS, some require a MySQL restart. Amazon forces the whole server to restart, increasing this downtime from a few seconds (when you roll your own) to many minutes. And while some parameters can be changed online, Amazon can provoke some strange behavior that is not always predictable.

With the frequency of these types of changes, you’ll quickly grow tired and frustrated with RDS.

EBS Snapshots are not portable

As mentioned above Amazon uses it’s standard filesystem snapshot technology to perform backups. While this works well, it can be slow & unpredictable in a multi-tenant environment.

When you roll your own, you can take advantage of xtrabackup, and perform hot backups against your database with zero downtime. This is a real godsend. What’s more they are portable, and can be moved to any other server even ones not hosted in Amazon’s cloud!

Promoting a read-replica is slow too!

One feature that Amazon touts is creating copies or “read replicas” of your data. These are great and can facilitate easy copying of data. However promoting these again brings unnecessary restarts which are slow.

When you roll your own, you can promote a read-replica or read-only slave in seconds. A few seconds can seem invisible to end users, while minutes will be perceived as a real outage or downtime.

Read: Is zero downtime even possible with RDS?

4. Is migration an option?

So what to do? As I mentioned above, there are real advantages to startups deploying their first database. It really does help. I would argue for many it can be a good place to start.

If you’re starting to outgrow RDS and frustrated with the limitations, performance tuning headaches & unneeded downtime, luckily you have options.

Migrating off of RDS onto a physical server can be done in a number of ways.

o slave off of the master

Here you build a MySQL slave on a standard EC2 instance, with your RDS instance as the master. When you’re caught up, bring your site down temporarily. Reset the slave & set to read-write mode. Then point your webservers at your new EC2 instance and bring the site back up. If done carefully 10 to 20 seconds of downtime should be plenty.

Don’t forget to run through the process with a firedrill first!

o dump & import

Another way to move your data may be MySQLdump. This option would be slower & bring a lot more downtime, but possibly necessary in some cases.

Also: 5 Reasons to move data to Amazon Redshift

5. Speed: It’s the database

Fred Wilson says speed is the number one feature of a web application. If customers are frustrated & waiting, they may leave & not come back. On the web it can be everything.

Many firms are rushing to database as a service to simplify administration. While that’s wonderful at the beginning, as you grow performance will become more of a day-to-day concern. And when it does, the database is going to be big on your list of headaches.

Web application performance inevitably involves the database and while it does, your decision to choose database as a service may come into question. Don’t be afraid to bite the bullet and manage things yourself when that time comes.

Also: Is upgrading RDS like a shit-storm that will not end?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don’t work with recruiters

Howto automate MySQL slow query analysis with amazon RDS

iRobot1

If you’ve used relational databases for more than ten minutes, I hope you’ve heard of slow queries. Those are those pesky little gremlins that are slowing down your startup, and preventing scalability you so desperately need.

Luckily there’s a solution. What I’ve found is if I send a report to developers every week, it keeps these issues front and center, for folks that are very busy indeed.

The script below is for RDS, but you can surely modify it if you have a physical server or roll-your-own MySQL box on Amazon. Take a look & enjoy!

Join 26,000 others and follow Sean Hull on twitter @hullsean.

1. install percona tools

Percona as many probably already know, are a wildly successful services firm that support MySQL and related technologies. They also have a very popular & scalable MySQL distribution by the same name.

Even if you’re not using Percona MySQL, you definitely want to get ahold of the percona toolkit. It provides all sorts of useful tools, including the one this article is based on, query-digest.

This tool takes your stock MySQL slow query logfile as input, and summarizes it into a very useful and readable report. Formerly mk-query-digest, it’s not called pt-query-digest. See below.

You can install the percona tools easily by grabbing the repository file and installing that with rpm. From there you can just use yum or apt-get depending on your distribution.

Related: Why a killer title can make or break your content efforts

2. install aws command line tool

Amazon has consolidated all it’s command line tools into a single one called just “aws”. The options can be a little arcane, and the error messages misleading besides. What’s good though is it is slightly easier to install & configure.

Do you already use Python? Install it this way:


$ pip install awscli

If not, you’ll need to dig into the aws cli installation instructions further.

Also: Do managers underestimate operational costs?

3. edit .aws/config

After you get the tool installed, you need to setup your environment. I edited a file named /home/shull/.aws/config as follows:


[default]
region = us-east-1
aws_access_key_id = BLIBJZMKLWIL5UTNRBMQ
aws_secret_access_key = MF5J/2z7HmN92lQUrV12ZO/FBXNjDVjL52TNRWsG

Those access_key_id and secret_access_key you can find on your amazon dashboard. Click upper right hand corner under your name, select the menu item “Security Credentials”.

Check out: Are SQL Databases Dead?

4. edit send_query_report.sh

I wrote the script below so you can fairly easily edit it.


#!/bin/bash
#

# get the rds db instanceID from command line (or crontab) entry
#
AWS_INSTANCE=$1

# here's where we'll store the latest slowquery.log
#
SLOWLOG=/tmp/rds_slow.log
#SLOWLOG=`/bin/ls -tr /home/shull/*.log | /usr/bin/tail -1`

# fetch slow query log from rds box
# here I always grab the latest one.
#
/usr/local/bin/aws rds download-db-log-file-portion --db-instance-identifier $AWS_INSTANCE --output text --log-file-name slowquery/mysql-slowquery.log > $SLOWLOG

# query report output
SLOWREPORT=/tmp/reportoutput.txt

# pt-query-digest location
MKQD=/usr/local/bin/pt-query-digest

# run the tool to get analysis report
$MKQD $SLOWLOG > $SLOWREPORT

# today's date in a variable
TODAY=`/bin/date +\%m/\%d/\%Y-\%H:\%S`
#YESTERDAY=`/bin/date -d "1 day ago" +\%m/\%d/\%Y-\%H:\%S`

# report subject
SUBJECT="Sean Query Report -- $TODAY "

# recipient
EMAIL="hullsean@gmail.com"

# send an email using /bin/mail
/usr/bin/mailx -s "$SUBJECT" "$EMAIL" < $SLOWREPORT

Note, if you don't have mailx installed, it should be available in your repository. Use apt-get or yum as necessary to get it installed.

Also: Is high availability overrated & near impossible to deliver?

5. Add to crontab

After you've tested the above script from command line, you will want to add it to a weekly cron job. Voila, automation! Don't forget to chmod +x to make it executable. 🙂


00 09 * * 5 /home/shull/send_query_report.sh seandb

Read: Are MySQL DBA's impossible to find?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don't work with recruiters

Connect to MySQL in the Amazon Public Cloud

MySQL on Amazon Cloud AWS

Troubleshooting MySQL on Amazon can be a real test of patience. There are quite a few different things to watch out for in terms of connectivity & networking. Sometimes a checklist can help.

Join 16,000 others and follow Sean Hull on twitter @hullsean.

Here’s my exhaustive list of things that can block you.

1. Be sure to create users & grants

Chances are you did something like this to create your user:


mysql> CREATE USER ‘sean’@‘localhost’ IDENTIFIED BY ‘password’;
mysql> GRANT ALL PRIVILEGES ON sean_schema.* TO ‘sean’@‘localhost' WITH GRANT OPTION;

But that won’t help you when connecting from a remote Amazon box. So what to do? Here’s an example:


mysql> CREATE USER ‘sean’@’10.10.%’ IDENTIFIED BY ‘password’;
mysql> GRANT ALL PRIVILEGES ON sean_schema.* TO ‘sean’@‘%’ WITH GRANT OPTION;

You may need to make your source IP wildcard *more* aggressive. For example consider ’10.%’. You *may* even with with ‘%’ which allows *all* source IPs. This may sound dangerous, but if you use a tight security group (see item #3 below), you can still be safe.

Related: Why Oracle Won’t Kill MySQL

2. Make sure iptables is not a problem

IPTables is a Linux service that acts like a private firewall for each server. Some AMIs will have it enabled by default. If you’re having trouble like I did, this can definitely trip you up. That’s because your connection will fail silently without telling you, hey the OS won’t let me into that port!

If you are a networking pro you’ve probably already fiddled with iptables. Feel free to add specific rules, and keep it turned on. However I’d recommend just disabling it completely, and using your Amazon security groups to protect your ports.


$ /etc/init.d/iptables stop
$ chkconfig --list iptables
iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off
$ chkconfig --del iptables
$ chkconfig --list iptables
service iptables supports chkconfig, but is not referenced in any runlevel (run 'chkconfig --add iptables')

Also: Are SQL Databases Dying Out?

3. Test & verify amazon security group settings

Security groups in Amazon can be tricky. I recommend the following:

o create a security group webserver_group
– allow port 80 from 0.0.0.0/0
– allow port 443 from 0.0.0.0/0
– allow port 22 from

o create a security group db_group
– allow port 22 from
– allow 3306 from

What’s happening here? We can’t specify a fixed set of IP addresses because they can change in Amazon. So essentially what we’ve done is say *any* requests from servers in our Amazon package, which are in the webserver_group security group, can connect to port 3306. Pretty cool right?

This means we’re pretty locked down. No internet connections to 3306, so we can be a little looser (see item #1 above) about our grants and source IPs.

What about if you want to use your GUI tools to hit your Amazon hosted MySQL boxes? Say you like to use the Oracle Workbench, Navicat or Toad to connect to MySQL. One way you could do this is configure your db_group to allow 3306 from your office subnet. Then anyone VPN’d into your office will be able to use the tools they like.

Another option is to use Amazon VPC for your servers. You’ll setup an Amazon Virtual Private Gateway, which is a direct VPN connection between Amazon’s datacenter and your datacenter. This can be a messy process, and you’ll want to contact your network admin to help. Once it’s setup, amazon boxes appear to sit on your office or datacenter network. Cool stuff!


$ mysql -h xxx.xxx.xxx.xxx -u admin -p
Enter password:
ERROR 2003 (HY000): Can't connect to MySQL server on 'xxx.xxx.xxx.xxx'

Read this: Why are MySQL experts in such short supply?

4. MySQL network settings

If MySQL is bound to the wrong IP address you can have real problems. First be sure skip_networking is OFF. If it is ON change it in /etc/my.cnf & restart MySQL.


mysql> show variables like 'skip_net%';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| skip_networking | OFF |
+-----------------+-------+
1 row in set (0.00 sec)

The other MySQL setting that can be problematic is bind-address. First check what it is set to:


$ cat /etc/my.cnf | grep bind
bind-address=127.0.0.1

This isn’t going to allow remote connections. In amazon however, your IP address may change upon reboot. So there is a special setting to allow binding to any IP:


bind-address=0.0.0.0

Related: Bulletproofing MySQL Replication with Checksums

5. installing mysql client & telnet for troubleshooting

You have two options for troubleshooting on the webserver side. If you’re simply trying to check by mysql command line, you may get blocked up if the network settings & security groups aren’t configured right. So use telnet first.


$ yum install -y telnet

$ telnet 10.10.10.1 3306
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
4
5.1.71??gu9Y6B'/y9Oay`QV

If you don't get a responce, it's not an issue with users or grants, but rather that the port isn't opened. Check iptables, check bind-address and check security groups.

Check this: Top MySQL DBA Interview Questions

6. SE Linux related issues

SE Linux will do a lot of good, if managed properly. However if you're not aware of it's existence, it can be very very frustrating. Symptoms can be as abstract as allergies, a cold or flu. It can monitor files, and prevent MySQL from being able to write where it needs to,

Read this: Migrating MySQL to Oracle

7. RPM & later centos yum repo install conflicts

I had real problems doing a custom install for a customer. They didn't want to use a repository for various settings, but preferred downloading RPMs. There were a few other customizations which were tripping things up.

Based on all the connectivity issues I was having, I backed out of the RPM based install, and then ran through a stock yum install. After doing that, I started seeing these weird errors in the mysqld.log

120328 21:32:40 [ERROR] Can't start server: Bind on TCP/IP port: Address already in use
120328 21:32:40 [ERROR] Do you already have another mysqld server running on port: 3306 ?
120328 21:32:40 [ERROR] Aborting
If I run "netstat -nat | grep 3306" in my terminal, I get the following:
tcp4 0 0 *.3306 . LISTEN

I spent hours spinning my wheels and not able to figure out what was happening here. At first it seemed a leftover pid file was the culprit. In the end it appeared the *old* /etc/init.d/mysql script was still in place, and the new yum packages wouldn't work with that.

I ended up just scrapping the whole box, and starting from scratch. Sometimes you have to do that. After a clean build, all was fine.

Related: RDS or MySQL 10 Use Cases

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don't work with recruiters