Encrypt external hard drive without erasing data?

[Matsaki]

I have a external hard drive I use for TimeMachine backups. Now I was wondering if I can make this disk encrypted without reformat and erasing the data on that disk?

Many thanks!

 

[JeffCGD]

I have a external hard drive I use for TimeMachine backups. Now I was wondering if I can make this disk encrypted without reformat and erasing the data on that disk?

Many thanks!

I don't think you can do encrypt in place for Time Machine Backups at all (need to do on drive setup).