Does UFS2 send BIO_FLUSH to GEOM when update metadata (with softupdates)?

[Lev Serebryakov]

Hello, Kirk.
You wrote 26 ноября 2011 г., 21:12:34:

> Kostik has it right. The requirement for SU and SU+J is simply
> that the underlying I/O subsystem not issue bio_done on a write
> until it is on stable store. If the I/O subsystem wants to cache
> it for a while (multiple seconds) before writing it to disk that
> is fine (SU thinks in terms of 30-second intervals). The only
  Ok, These "multiple seconds" are good news.

> thing that SU requires is that the subsystem NOT lie by issuing
> the bio_done before it has committed the data to disk. Perhaps
> what we need is a "delay acknowledgement until done' flag to make
> this clear.
   Ok, such flag (and "30 seconds is Ok" statement) will be enough
 for me (RAID5) to implement robust but high-performance write
 queuing.
   But FSYNC flag will be nice and useful too, IMHO.

-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>