Re: [MooseFS-Users] MooseFS 4.0 and new features

[Gandalf C. <gan...@gm...>]

Il giorno dom 20 mag 2018 alle ore 17:13 Marin Bernard <li...@ol...>
ha scritto:
> What is certain, however, is that the performance cost of fsync with
> ZFS is far higher than with another FS. In standard async mode, ZFS
> delays and batches disk writes to minimize IO latency. fsync predates
> this optimization without disabling it, and as a result performance
> drops quickly

This is obvious but the question is not if enable or not fsync.
The real question is: what happens when HDD_FSYNC_BEFORE_CLOSE is set to 0 ?
What if client open a file with FSYNC set? Will Moose honor this and then
send that to the underlying storage
regardless the value of HDD_FSYNC_BEFORE_CLOSE ?

In other words: is HDD_FSYNC_BEFORE_CLOSE an additional measure to force
FSYNC (on file close) even if client
didn't ask for it ? or is HDD_FSYNC_BEFORE_CLOSE the only way to issue
FSYNC in MooseFS?