Presentation for MongoDB Buenos Aires 2012

1. MongoDB
At MercadoLibre
Wh at h ave we le a rned

2. Overview
About MeLi
Why MongoDB?
Use cases
Lessons Learned
Wrapping Up

3. MeLi - Platform

4. MeLi - Facts!
20M requests / minute
50K requests / sec (peaks)
4 Gb bandwidth / sec

5. MeLi - Facts!
20M requests / minute
50K requests / sec (peaks)
4 Gb bandwidth / sec
Our farm
+1000 physical server
+6000 virtual instances

6. MeLi - Inside
Lot of fun here playing with new stuff :P

7. MeLi - Inside
Lot of fun here playing with new stuff :P
Our NoSQL stack
Redis
Memcached
Hadoop

8. MeLi - Inside
Lot of fun here playing with new stuff :P
Our NoSQL stack
Redis
Memcached
Hadoop
.... and of course

9. Why MongoDB?
Horizontal Scaling
High Availability
Performance
Flexible Data!

10. Why MongoDB?
Horizontal Scaling
High Availability
Performance
Flexible Data!

11. Why MongoDB?
(... and more)
JavaScript(‘ing)
Polyglot
Open Source
Awesome Community
Support

12. Support :-)

13. Use Cases
DB Documents
Social +700M
Orders +23M
Feedback +3M
Emails +61M
Items +200M
Logging +332M

14. Use Case: Social
Store Meli’s users social data
LOT of data (friends, likes, ...)
> 500 Gb
> 700 M documents
12 shards servers : 4 replica set
Each replica set = 3 servers
80Gb per instance

15. Use Case: Social
Sp
ec
@T ial
ioB thk
or st
Store Meli’s users social data rac o
ho
LOT of data (friends, likes, ...)
> 500 Gb
> 700 M documents
12 shards servers : 4 replica set
Each replica set = 3 servers
80Gb per instance

16. Use Case: Items
1 Item!

17. Use Case: Items
1 Item!

18. Use Case: Items
1 Item!

19. Use Case: Items
1 Item!
N x N x N ... > 100k rows

20. Use Case: Items
1 Item!

21. Use Case: Logging
Capped Collections!
Info logs
RabbitMQ messages
Track certain use cases
Errors logs
Something bad happen...
Recuperable errors with retry handler

22. Lessons Learned
Storage
File System
NSF: Bad choice, Poor results
Ext4: Far much better
Mount Options
Reducing Disk IO by mounting partitions with noatime and nodiratime
Track disk performance
iostat -xm 2 (%util column < 100%)

23. Lessons Learned
VM’s
Shard instances
4 cores
>= 16 Gb ram
Config server
low cpu consumption
1Gb ram / 1Gb storage
Mongos
runs along with the webserver (client)
1 mongos x webserver

24. Lessons Learned
Monitoring
Disk usage (with zenoss)
Ping health check
curl --connect-timeout 3
--write-out %{http_code}
--silent
--output /dev/null
http://localhost:28017/_status

25. Lessons Learned
Monitoring MMS - It’s free!

26. Lessons Learned
Plan your actions!
Shard key
Upgrades
Cfg Servers
+ bad decisions = Lot of rework
...

27. Lessons Learned
Plan your actions!
Shard key
Upgrades
Cfg Servers
+ bad decisions = Lot of rework
...
Study
Think
Plan
Hands On!

28. Wrapping Up!
Meli loves MongoDB!

29. The End
Questions?
{
name : "Pablo Molnar",
title : "Software Engineer",
work : "MercadoLibre",
location : "Buenos Aires",
twitter : "@pablomolnar"
}