如何mongorestore 2.6.11转储到3.2.5系统？

Question

I've noticed an anomaly after performing a mongorestore from a 2.6.11 dump (from another system) to a 3.2.5 system. In a nutshell, the names of the collection files on the new system (in /var/lib/mongodb ) are named differently and follow this format:

collection-55--6670716476518949126.wt
index-1--6670716476518949126.wt

Whereas on the old system, the collections were in /home/mongodb and followed this naming convention:

collection_name.0
collection_name.1
collection_name.ns

Strangely, everything seems to be "working" though, even though the ~150MB collection file sizes on the old system aren't represented in the new collection file sizes (which are ~150kb).

I was following the answer in:

How to migrate MongoDB 2.6 to 3.0 with WiredTiger

Which basically suggests:

• Perform mongodump .
• Stop mongod
• Upgrade MongoDB version
• Convert the old config file at /etc/mongod.conf to the new YAML format.
• Restart mongod
• Perform the mongorestore on the dump.

As I am doing a mongorestore to a fresh MongoDB 3.2.5 install, however, I already have a config file in the YAML format (see below).

So the only step it seems I need to do is the mongorestore - which I have done and resulted in the anomalies noted above.

My questions are:

01) Are there any other steps I should have performed?

02) Are these file naming 'anomalies' expected?

03) Why is there such a large discrepancy in collection file sizes?

I ask in order to avoid any problems that may arise later due to missing an important step.

/etc/mongod.conf

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# Where and how to store data.
storage:
  dbPath: /var/lib/mongodb
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# network interfaces
net:
  port: 27017
  bindIp: 127.0.0.1


#processManagement:

#security:

#operationProfiling:

#replication:

#sharding:

## Enterprise-Only Options:

#auditLog:

#snmp:

Answer 1

the file names are correct as mongoDb uses now wired tiger as default storage engine. The size associated can be different as WT uses different approach when storing documents in file

see more here