Database Migrations - Lessons from Failure, and Tips for success

mbseid.com

4 pointsmbseid2 comments

> After every write to our database, we had to wait for the disk to catch up.

After all of the guffaw we just went through with MongoDB, is disabling fsync the right solution to speeding up MySQL migrations?

Nope, it probably isn't best for performance. It wasn't my call to make, and it has been operating like that for years.

But for data stability, I see why it was done. It is a trade off, one that we may reconsider down the line.

Edit: Misread the question. I'm not exactly sure, but it significantly improves speed, enough for us to complete the migration, then switch it back on during production.

One note: when running on a VM, it seems not to flush to disk regardless of the OS setting. Probably because of the virtualization software

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