implications of mixed mode

[Lukas Pirl <btrfs@lukas-pirl.de>]

Dear list,

if a larger RAID file system (say disk space of 8 TB in total) is
created in mixed mode, what are the implications?

>From reading the mailing list and the Wiki, I can think of the following:

+ less hassle with "false positive" ENOSPC
- data and metadata have to have the same replication level
  forever (e.g. RAID 1)
- higher fragmentation
  (does this reduce with no(dir)atime?)
  -> more work for autodefrag

Is that roughly what is to be expected? Any implications on recovery etc.?

In the specific case, the file system usage is as follows:
* data spread over ~20 subvolumes
  * snapshotted with various frequencies
  * compression is used
* mostly archive storage
  * write once
  * read infrequently
* ~500GB of daily rsync'ed system backup

Thanks in advance,

Lukas