Time Machine: erroneous "not enough space" error?

[bigwig]

I'm getting a "not enough space" error when trying to back up a 1TB disk to a 1TB disk. Time Machine says it needs 953G to back up the 794G on my disk. The backup disk is newly formatted with Apple Partition Map. Any idea what's causing this?

 

[Enigmafan420]

I'm getting a "not enough space" error when trying to back up a 1TB disk to a 1TB disk. Time Machine says it needs 953G to back up the 794G on my disk. The backup disk is newly formatted with Apple Partition Map. Any idea what's causing this?

Never seen this before-what options did you use when partitioning the HD?

It would not surprise me if TM needed a small amount of additional space for the back-up (an amount larger than the final "product". But nearly 200 GB seems sort of excessive to me.

 

[bigwig]

Never seen this before-what options did you use when partitioning the HD?

One partition, Apple Partition Map.