[OpenAFS-devel] Re: The ihandle sync thing

[Andrew Deason]

On Thu, 28 Mar 2013 11:46:21 -0400
chas williams - CONTRACTOR <chas@cmf.nrl.navy.mil> wrote:

> > Doesn't pdflush guarantee this? That something doesn't stay around in
> > memory forever.
> 
> On a modern Linux, yes.  On other operating systems, I don't know.  I
> imagine Solaris has something but off the top of my head I have no
> idea its behavior with regard to ufs and timely flushing of dirty
> pages.

Solaris ZFS at least should be fine; I've gotten complaints about the
backgrounding behavior before about how it's completely useless on ZFS.

> Given the plethora of filesystems and platforms supported by OpenAFS,
> it is perhaps best to be conservative with regard to the defaults and
> let savvy admins shoot themselves in the foot instead of doing it for
> them.

That's why I'm thinking there should be an option of sync vs no-sync
(and not have the delayed syncs). If you want a 'delayed sync' guarantee
behavior, you can rely on the OS for it. If your OS doesn't do that,
then don't use it.

Or we can whitelist certain platform/filesystem combinations, where we
are confident that delayed sync is useless, and turn off the delayed
syncs there.

-- 
Andrew Deason
adeason@sinenomine.net