Write cache, is write cache, is write cache?

[Bruce Cran]

On Mon, 24 Jan 2011 06:42:36 -0800
Jeremy Chadwick <freebsd at jdc.parodius.com> wrote:

> In the case of ZFS, why would all data be written to the disk every
> single time there's a write(2) operation?  Performance-wise that makes
> absolutely no sense.  So there is absolutely going to be a "window of
> failure" that can happen, and mirroring/raidz can recover from that,
> as a result of the checksum "stuff".

Very few people would expect data to be on disk after every write(2),
but they should expect it to be on disk after every fsync(2) - my
understanding is that databases depend on that for correct operation.

-- 
Bruce Cran