Dreadful gmirror performance, though each half works fine

Pete French petefrench at ticketswitch.com
Thu Apr 17 18:25:06 UTC 2008

> I have experimented with this rather extensively and have operationally
> decided not to use ggated in combination with gmirror --- it doesn't appear
> to work as well as one might expect.

Ah, thats unmfortunate :-( I oroginally started off using the
iscsi initiator and target, which did work O.K., but when actually
ran live ended up locking up after several hours,a nd then panicing
the kernel. So not ideal - but when it was working it was fine. ggated
seems the opposite - doesnt crash, but performance is not suitable for any
kind of real use.

> I'm somewhat vaguely wondering if zfs with one local and one ggated disk
> will work well.

I tried ZFS for a while myself, and it works O.K., but has a tendency
to panic if it wants memory which it can't get. Despite the many different
guides available, I never managed to get it to the point where I would
be happy to use it on a production system without worrying about it
suddenly becomming memory hungry and dieing.

Thanks for the inout though - I am doing some more experimentation
with ggate (basically raing some buffers as per a thread I found) and
seeing if that helps.

BTW, I think ggate is the problem and not gmirror here - gmirror on top
of iscsi works fine as I said.

More information about the freebsd-stable mailing list