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I browsed the Amazon RDS pricing site today and now do want to know how they actually calculate the I/O rate? What does "$0.10 per 1 million requests" really mean?

Can anyone give some simple examples how many I/Os a simple query from EC2 to a MySQL on RDS produces?

John Rotenstein
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eisberg
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1 Answers1

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In general it is a price for EBS storage service. Amazon claims something like this for EBS (section Projecting Costs):

As an example, a medium sized website database might be 100 GB in size and expect to average 100 I/Os per second over the course of a month. This would translate to $10 per month in storage costs (100 GB x $0.10/month), and approximately $26 per month in request costs (~2.6 million seconds/month x 100 I/O per second * $0.10 per million I/O).

If you have a running application on Linux, here is an article how to measure cost for EBS:

okrasz
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    I/O operation is read or write operation on disc, so the instruction sent by system to block device (hard drive). – okrasz Aug 03 '11 at 15:42
  • so if you were using AWS RDS, and you sent a query like "Select * from aTable" where aTable has 1000 rows, how many IOs would that be? – mcmillab Apr 02 '13 at 09:35
  • @mcmillab One open connection to a database is one i/o - doesn't matter how many rows you are returning. – FredTheWebGuy Apr 21 '13 at 08:25
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    @Dreadful_Code Actually, that doesn't appear to be the case, 'how many rows you're returning' does seem to affect how many I/O requests are made: http://dba.stackexchange.com/a/17427 – Ali Sep 14 '13 at 08:31
  • @ClickUpvote Good point! Revision: It doesn't matter how many rows you return if the query results can be stored in the query cache. However, if you have a complicated query that spans a lot of tables and/or return a large number of rows, AND the query is unable to be cached, then yes you may incur an IO penalty. Your average use case, however, should average to IO operation per query, at least as a rule of thumb. – FredTheWebGuy Sep 17 '13 at 05:14