aws-ec2-raid

Simple RAID0 (disk striping, for speed) on AWS EC2 instances. Get faster EBS for the same price as regular, slower EBS. The closest thing to a free lunch on AWS, outside of the free tier. Inspired by AWS documentation: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/raid-config.html

Status

The status of this project is "failed proof of concept". It works ok, but the measured performance improvement was very disappointing, and it's not clear why.

Usage

./create-volumes.py COUNT SIZE 
./free-volumes.sh | ./mount-volumes MOUNTPOINT

Where :

• COUNT is the number of EBS volumes to be created and configured in RAID0 mode.
• SIZE is the size in GB of each volume
• MOUNTPOINT is the path for the mount in the local fs, e.g. /mnt or /data

Example

To setup an 8-volume 80GB RAID0 (striped across 8 volumes of 10GB each) from scratch in an Ubuntu Linux instance:

git clone https://github.com/atramos/aws-ec2-raid 
cd aws-ec2-raid
sh install_pip3_boto3.txt
mkdir /raid0
./create-volumes.py 10 8
./free-volumes.sh | ./mount-volumes /raid0

Benchmarks

• Test executed on a t3.medium instance, Ubuntu Linux 18.x
• 8-way RAID0 array
• Test procedure: tar -cf - . > /dev/null on a directory containing 43GB of data files
• RESULT: raid0 was approximately 42% faster than a raw EBS volume

Troubleshooting

Issue

• botocore.exceptions.ClientError: An error occurred (UnauthorizedOperation) when calling the DescribeVolumes operation: You are not authorized to perform this operation.

Resolution

• Your AWS credentials need permissions to DescribeVolume, CreateVolume, AttachVolume, etc. 1 Create an IAM Role and give it full EC2 access:IAM ---> Roles --->Create Role --->Aws Service - EC2 ---> Permissions: AmazonEC2FullAccess 2 Attach the role to the instance: Instance Settings ---> Attach/Replace IAM Role

How does it work?

• The script runs on the EC2 instance where array is going to be mounted
• The script creates the EBS volumes using boto3 API
• The script attaches the new volumes to the instance it's running on
• The script runs the mdadm commands as described in the AWS documentation
• The script formats the volume
• The script mounts the volume
• The script updates /etc/fstab so that the volume persists on reboot

Future Enhancements

• RAID10? There are online rumours that say EBS is unreliable. If true, it would be good to mirror the RAID0.
• More testing: AWS documentation indicates 8x is the sweet-spot for performance. This is the only setup I tested, and it was unimpressive.
• More testing: I have not tested this, but, to avoid snapshot corruption, you should probably not perform "no reboot" EBS snapshots.