Migrate to wiredTiger

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Need Help

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Oct 20, 2016, 7:50:53 PM10/20/16

to mongodb-user

We are currently on mongodb 3.0.12, MMAP storage engine. One complaint we have is mongodb is TOO slow, and the db locking is inefficient. We are thinking about migrating to wiredTiger. However, we have over 2 terabytes of data both in house and in customer's site, which would need to be done in one day, hopefully under 8 working hours. We have done some benchmark when mongodb 3.0 first came out. Unfortunately, the result was not encouraging. We would like to know if it is possible to do the migrating under reasonable time interval. Thanks!

Kevin Adistambha

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Nov 2, 2016, 2:03:07 AM11/2/16

to mongodb-user

We are thinking about migrating to wiredTiger. However, we have over 2 terabytes of data both in house and in customer’s site, which would need to be done in one day, hopefully under 8 working hours.

We would like to know if it is possible to do the migrating under reasonable time interval. Thanks!

“Reasonable” could mean different things depending on requirements and circumstances. For example, some scenario can tolerate 8 hours of downtime, while others cannot. Migration time and complexity also depends on whether you are migrating a standalone node, a replica set, or a sharded cluster. For more details:

Having a replica set arguably provides more flexibility, since you can perform a rolling upgrade. This ultimately allow you to have zero downtime while the upgrade is progressing. Note that you can have a replica set with mixed storage engines, although it’s not recommended to run using this setting for an extended period of time.

MMAPv1 and WiredTiger operates very differently. While it is true that WiredTiger has a host of improvements compared to MMAPv1 (especially concurrency improvements), extensive testing using your specific workload, use case, and application is recommended before any drastic change to your setup. Also during this change, having a verified backup is essential. Please see WiredTiger storage engine page and FAQ: Concurrency for more information.