[systemd-devel] [EXT] Re: consider dropping defrag of journals on btrfs

[Phillip Susi]

Chris Murphy writes:

> It's not interleaving. It uses delayed allocation to make random
> writes into sequential writes. It's tries harder to keep file blocks

Yes, and when you do that, you are inverleaving data from multiple files
into a single stream, which you really shouldn't be doing.  IIRC, XFS
has special io streaming modes specifically designed to *prevent* this
from happening and record multiple video streams simultaniously to
different parts of the disk to keep them from being fragmented to hell
like that.