How many volumes can I have in a MySQL EBS stripe?

Answer

The maximum EBS stripe count that you can use with our ServerTemplates that support EBS striping is 14 (/dev/sdk to /dev/sdx).  Even though the number of available devices on Linux-based instances is technically 17 (/dev/sdj, /dev/sdk . . . /dev/sdz), the maximum number of volumes that you can successfully use with our ServerTemplates is 14.

Note: EBS striping on Windows-based instances is currently not supported.

Most users will typically only need to use a stripe count between 1 and 5, which is why the script is pre-populated with a drop-down listing values from 1 to 5. However, you can specify a larger stripe size by using the "override dropdown?" option to specify a larger EBS stripe count.

RightScale's preliminary performance tests have shown that a stripe count of 2 or 4 yield positive performance gains. Of course, since no application is the same, you should perform your own performance tests to determine the optimal number and size of your EBS stripe for your own application. There are several factors to consider when determining the preferred stripe count for your database:

• Disk size - Does the size of your database warrant using a larger EBS stripe?
• Size versus quantity - Is it better to increase the size of each volume in the stripe or increase the quantity of volumes in the stripe?
• Disk performance - Are there a lot of writes being made to the database, or mainly reads?
• Snapshots - How long does it take to complete a backup (i.e. snapshots of each volume in the EBS stripe)?  Do you need the backups to be completed quicker?
• Cost - Increasing volume sizes or the total number of volumes (and subsequent snapshots) will increase overall costs.

Important! Always test any setup thoroughly in a staging deployment (sandbox) before using it in a production environment.

In cases with large databases, we've noticed customers using stripe counts greater than 5 in order to reduce the time required to complete periodic backup snapshots. Remember, the larger the volume, the longer it takes to create a snapshot. For example, let's assume that it takes about 1 minute to create a snapshot of a 1 GB volume. If your database is 100 GB in size, it would take 100 minutes to complete a snapshot of a single 100 GB volume.  However, if you use a stripe count of 10, it would only take 10 minutes to complete a backup of your database where each volume is 10 GB in size, since the script always creates an EBS stripe with volumes of equal size.