The document provides 5 steps to scale MongoDB: 1) optimize queries with indexes, 2) understand working set size and fit within RAM, 3) tune the file system for fast access, 4) choose disks like RAID 10 for throughput, and 5) shard for writes and RAM across multiple servers each handling part of the data range.

1. 5 Steps to Scale your MongoDB

2. 1. Optimize your Queries
query = db.coll.find({title:”My blog”})
query.explain();
{
"cursor" : "BasicCursor",
cursor : BasicCursor
"indexBounds" : [ ],
"nscanned" : 57594,
"nscannedObjects" : 57594,
"n" : 3,
"millis" : 108
}
db.coll.ensureIndex({title:1})

3. 2. Know your working set size
Active
Documents +
Used Indexes
RAM
Disk

4. 3. Tune your file system
• EXT3 == bad
– Slow file allocation & initialization
• EXT4 / XFS == good d
• Access time tracking == bad
– noatime, nodiratime

5. 4. Choose the right disks
Single Disk
~200 seeks / second
RAID 0
~200 seeks / second ~200 seeks / second ~200 seeks / second
RAID 10
~400 seeks / second ~400 seeks / second ~400 seeks / second

6. 5. Sharding for
g
MongoS MongoS
writes & RAM
Shard
Sh d 1 Shard
Sh d 2 Shard
Sh d 3 Shard
Sh d 4
0..10 10..20 20..30 30..40
Primary Primary Primary Primary
Secondary
y Secondary
y Secondary
y Secondary
y
Secondary Secondary Secondary Secondary