On 5/8/07, mickey <[EMAIL PROTECTED]> wrote:
On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote:
> George C wrote:
> > I've just stumbled across the SoftUpdates section in the FAQ, and was rather
> > surprised that I had never seen/heard of this feature before. Before
> > I mount any
> > partition using softdep, I thought I'd google, browse the archives, etc.
for any
> > information about when/where they should be used.
> >
> > Although I've found a plethora of information about soft updates, much of
it is
> > either contradictory or incomplete.... I thought I'd ask here for
clarification.
> >
> > Is it always best to mount /, /tmp, /usr, /var, /home with softdep?
> > Under what curcumstances would it not be appropriate?
>
> Softdeps don't do anything for you if you are mostly reading from disk,
> or if the partition is mounted read-only. It's about writing.
of course they do. there are still atime updates
for example that will be handled if not mount read-only.
So, given the above two comments... sounds like softdep would be
both "safe" and beneficial for (at least) /usr and /var. Probably also for
/var/www.
Still curious how they would work on, say, /var/mysql or /var/postgresql,
but I can play with this on my own.
Has anyone already tried? Care to comment?
> All these machines have a perc5 raid controller using mfi driver.... does that
> make a difference?
yes... IF the RAID card has a write cache, SOME of the advantage of
softdeps may not exist. On the other hand, if it doesn't have the
battery, your write performance is so horrible, you probably want
softdeps badly.
Hmm. My cards do have a write cache w/ battery. So in this case, it
looks like softdep on any partition would be inappropriate....is that
correct? Is this simply because the raid card (with write cache) is
basically doing what softdep does?
Many Thanks for all the advice!
-George
