[Drbd-dev] Re: drbd in linux-ha cvs

[Philipp Reisner]

On Tuesday 07 September 2004 12:49, Lars Ellenberg wrote:
> On Tue, Sep 07, 2004 at 11:43:01AM +0200, Philipp Reisner wrote:
> > > the point was to have an easy way to _read_ all available information
> > > in a well defined way in one chunk. and having it in k=v form makes it
> > > direktly useable by bash, and easily useable by perl:
> >
> > Is it worth the trouble to maintain two interfaces in drbdadm ?
> >
> > Is it less rouble to maintain the
> >
> > CSTATE=$(drbdadm cstate r0)
> > LOCAL_STATE=$( $DRBDADM state $RES 2> /dev/null )
> > LOCAL_STATE=${LOCAL_STATE%/*}
> > LOCAL_STORAGE= $(drbdadm sh-ll-dev r0)
> > ...
> >
> > lines in the bash script you do ?
>
> the drbdsetup code needs a cleanup anyways, we really need to
> restructure what part ends up in some "public" header file, and what
> part really still belongs to drbd_int.h ...
>
> it is more clean to have one ioctl, get the full info, and output that.

Hmmm, the thing is, it is one ioctl. It is the DRBD_IOCTL_GET_CONFIG
ioctl. Only drbdsetup shows not show all the information in one call...

> I feel uneasy about introducing additional races by using several ioctls
> in a row (even if they all finish within one second). of course, once we
> have that info it could be stale already, but at least we have the
> guarantee that at some point in time it was correct.

This is of course an argument.

> btw, one more reason to have some kind of "suspend", ask about
> information, go figure, do some things, and only then "resume" to allow
> changes to take effect... (due in 0.8)
>
> as soon as we have a sane interface, I don't expect the internals to
> change so often, so the "maintenance trouble" is very low, either way.
>

I just not want to have two interfaces to get to the same stuff.

-Philipp
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