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I read a blog article somewhere that RAID10 on EC2 cuts down performance by half compared to RAID0.

But when you have critical database data on the volumes, how else do you prevent data loss in case a volume goes bad?

(I just had a case where one of the volumes in a RAID0 array stopped responding...)

I do have master/slave replication with log shipping but don't want to do a fail-over if RAID10 can help me avoid it.

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Hi, I've seen you said you are doing RAID 0 and trust in EBS reliability. Who's been working out for you? Is it better to have a backup strategy and do the snapshots than a mirroring? –  Maziyar Aug 7 '13 at 14:14
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2 Answers

My understanding is that raid1 doubles the writes,but can speed up the reads a lot.

How large is your database and how fast can you make backups of it?

I also thought RAID0 (striping only) made it MORE likely you could have a problem,i.e. one volume is lost and its good bye data.

One of the unexpected I/O oddities of Ec2 EBS volumes, is the first time you write to your EBS disk, it takes like 2x longer, than any subsequent write. I do a disk fillup to 50% with just dd if=/dev/zero of=/newdisk/bigfile1 bs=1024m count=1024, then wipe the big files and afterwards writes take more normal speeds.

This is a good ec2 dev forum article on ec2 disk I/O specifics. https://forums.aws.amazon.com/thread.jspa?messageID=220860

and this says EBS disks are bad for raid10

Amazon EC2 Disk Performance | AF-Design Feb 27, 2009 ... If you have a high number of reads or writes, which you likely do .... Pingback: Amazon EC2 Disk Performance and Why RAID 10 is bad for EBS ... http://af-design.com/blog/2009/02/.../amazon-ec2-disk-performance/

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The data is 40GB right now and growing by 5GB per month. I will use RAID0 right now and skip the RAID10. Trust Amazon to deliver the 99.9% EBS reliability they are promising... –  sayeed Mar 18 '11 at 6:42
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up vote 2 down vote accepted

Found this nugget from a RightScale blog entry discussing EBS reliability:

From a practical point of view what this means is that you should expect the same type of reliability you get from a fully redundant RAID storage system. While it may be technically possible to increase the reliability by, for example, mirroring two EBS volumes in software on one instance, it is much more productive to rely on EBS directly. Focus your efforts on building a good snapshot strategy that ensures frequent and consistent snapshots, and build good scripts that allow you to recover from many types of failures using the snapshots and fresh instances and volumes.

source: http://blog.rightscale.com/2008/08/20/amazon-ebs-explained/

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