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I've been playing around with Amazon's Web Services for over a year now, however I don't quite understand how it works. When I for example select an AMI of my choice from the EC2 console and I continue through the wizard, I reach the "Storage Configuration Tab". There are several options here.

There is the root volume tab and then there is the EBS volume tab. How do both of these differ? What is the maximum size I can allocate for each? How can I configure the EBS Volumes to work with my Instance? Say for example I decide to create 8 EBS volumes each with 25 GB of storage, for something like a Postgresql database which naturally installs on the root device, how I configure it so the database is stored across the 8 EBS volumes? In a sense, the 8 EBS volumes are seen as one 200 GB?

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up vote 1 down vote accepted

EBS volumes are merely block storage devices, which get assigned to /dev/xvdX type device nodes, just like "standard" hard drives would. To use them, create a new volume, associate it with your EC2 instance, using a free device node, create a new filesystem of your choosing on the device, mount them via /etc/fstab and use them however you'd like.

At the moment, the max EBS volume size is 1 TiB:

EBS Creation Dialogue

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Thanks for the clarification – noahandthewhale Apr 16 '13 at 17:30
@RiegieGodwin - sure thing. Did this answer your questions? – EEAA Apr 16 '13 at 17:43
yes it did, however let's say two years from now, my evergrowing database reaches the 200 TB mark, what other options do I have? Is it as easy as adding another drive? – noahandthewhale Apr 16 '13 at 17:58
You're going to run into many more issues before that point, requiring you to look into database sharding to multiple hosts. But yes, you can add additional EBS volumes at any point, without downtime. – EEAA Apr 16 '13 at 18:00
thanks for all the help EEAA you really helped me out. Now my last question is for something like storing the data of a database (like a postgresql database) how can I make sure the data is stored on the EBS volumes and not the root volume? – noahandthewhale Apr 16 '13 at 18:03

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