Change Storage Engine to WiredTiger for data from mongo backup

[Moshe Shperling]

BS"D

hi

we are running mongodb 2.6.1 and we would like to upgrade to 3.*  My question is that since we need to change storage engine can we do it with files that come from mongodb backup, instead of making mongodump/mongorestore (as it says in http://docs.mongodb.org/manual/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger)?

thanks

[Stephen Steneker]

On Friday, 31 July 2015 02:00:54 UTC+10, Moshe Shperling wrote:

we are running mongodb 2.6.1 and we would like to upgrade to 3.*  My question is that since we need to change storage engine can we do it with files that come from mongodb backup, instead of making mongodump/mongorestore (as it says in http://docs.mongodb.org/manual/release-notes/3.0-upgrade/#change-storage-engine-to-wiredtiger)?

Hi Moshe,

What sort of deployment do you have (standalone / replica set / sharded cluster)?

In order to change storage engines the data needs to be reimported as the formats on disk are not compatible. For a new deployment or standalone server you would use mongodump/mongorestore, but for an existing replica set (or sharded cluster backed by replica sets) the common approach is to do a rolling upgrade by syncing new replica set members configured with WiredTiger: http://docs.mongodb.org/manual/release-notes/3.0-upgrade/#change-replica-set-storage-engine-to-wiredtiger.

Note: since you are currently using MongoDB 2.6.1, you will first need to upgrade to at least 2.6.8 (ideally 3.0.5) if you are upgrading an existing replica set.

With MongoDB Cloud Manager you can choose the format for your backup, but changing storage engines for backup requires an initial sync (i.e. same outcome as adding a new replica set member with WiredTiger instead of MMAP): https://docs.cloud.mongodb.com/core/backup-preparations/#storage-engine.

Regards,

Stephen