Features/QED/OutstandingWork
Thanks to Kevin Wolf for collecting these points:
- Relying on file size - have we really considered all cases with respect to data integrity?
- Code review has brought up some corruption issues that are fixed by now, but have we covered everything?
- First dirty flag had to be added
- Then a bdrv_flush after COW
- What's next?
- Planned incompatible changes must be done as soon as possible. Checked this with Stefan, it's only zero cluster support.
- After a host crash an fsck is needed. Did anyone measure the time to start up when multiple guests on multiple hosts are recovering from a system failure? File system guys consider this a severe problem. [Update: Stefan has tested fsck time, but only with one image]
- Migration currently doesn't work with QED, likely breaks images
- QED doesn't work on block devices (required for some users)
- No support for encryption, compression, internal snapshots
- Non-technical issues:
- Burden of maintaining an additional image format (basically doubles image format related work; both development and QA) [Update: Sharing code might reduce the burden, though I guess for QA purposes it would stay two independent formats.]
- There are concerns that starting with a simple image format core and then adding one new thing after another on top is going to make code complexity grow very fast.
- Conversion of existing images is needed to take advantage of QED.