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Archive for April 7th, 2009

Java in Cloud

April 7th, 2009

This time it is real. Google just announced java for app engine.

Updates: And cron job in app engine as well.

Two differences I noticed from python gae. It deploys byte code (war file) instead of source code to cloud. Using xml instead of yaml.

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Yejun Uncategorized

Disk IO: EC2 vs Mosso vs Linode

April 7th, 2009

Recently I read an interesting idea on amazon EC2 forum about Raid0 strip on EBS to improve disk access performance. So I am very curious to know whether this idea actually works. Technically it is also possible to setup a raid system on Linode(referral link) as well, but it will be backed by same hardware (so I didn’t test this idea).

In this test I used bonnie++ 1.03e with direct IO support. These 3 VPS have slightly different configure. Mosso server has 256MB ram with 2.6.24 kernel and 4 AMD virtual cores. Lindoe vps has 360MB ram with custom built 2.6.29 kernel and 4 intel virtual cores. EC2 high-cpu medium instance has 1.7GB ram with 2.6.21 kernel and 2 intel virtual cores.

Here is the raw test result. On each VPS I run bonnie++ 3 times, then use median of 3 tests as the final result. The summary result is unweighted average value of different columns. Due to the memory size difference, I used different test file size. The EBS I used here is 4×10GB raid0.

In this table, -D means that test run with Direct IO option. The best results are highlighted. Direct IO test on EBS taking forever, so I didn’t finish that test.

.

Write (MB/s) Read (MB/s) Seek (#/s)

.

Mosso -D 32.4 52.9 219

.

Mosso 56.9 52.6 225

.

Linode -D 37.7 76 187

.

Lindoe 41.5 76.1 201

.

EC2 -D 32.4 50.7 220

.

EC2 18.9 39.2 210

.

EBS Raid0 52.4 23.1 1076

In this chart, I used logarithm scales and shifted origin in order to show the relative difference between them. So the column value does not reflect the real test results. Higher value is better.

Disk IO Chart

Conclusions: There is no clear winner in this test. Each VPS has the their high score in different category. Only one thing is clear, O_Direct does not work very well on EBS. Due to the nature of VPS, the Disk IO test is very unreliable. The performance I show here is not repeatable and may not reflect the true disk performance.

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