Date: Mon, 14 Aug 2006 20:43:28 +0200 From: Attila Nagy <bra@fsn.hu> To: freebsd-net@FreeBSD.ORG Subject: Re: Redundant/failover NFS servers - stale NFS file handle Message-ID: <44E0C450.8050602@fsn.hu> In-Reply-To: <200608141555.k7EFthXw092647@lurza.secnetix.de> References: <200608141555.k7EFthXw092647@lurza.secnetix.de>
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On 2006. 08. 14. 17:55, Oliver Fromme wrote: > We use NetApp Filer clusters (NAS) for that purpose. > They aren't cheap, but they work very well. I don't like blackboxes with nice GUIs. :) > NFS file handles are based on the inode number. That means > if you want to have a fail-over that's transparent for the > client, your NFS servers would need to have the same inode > numebrs for their files. Normally, the only way to achieve > that is to duplicate the file system from the master to the > slaves using dd(1). I've already did that (a vnode backed md), but that's not too comfortable in the long run. > There's another possibility, but I haven't tried it for > myself, so it's just theory. :-) You can try to put > geom_mirror (see gmirror(8)) on top of geom_gate (see > ggated(8), ggatec(8)). Then you will have a RAID1 with > one component local and the other component remote. > However, I think it only works reliably in read-only > mode. Yes, both of them must be read only, several years ago I've used a similar setup, but with a shared SCSI disk. Read only on the client side is OK for me, but is hard to maintain on the server side. I guess it would be possible to do this RW, mounted only on the master and if it fails, remounted (fscked, etc) on the slave, but I consider that a little bit hackish. I can solve this problem with Linux, but I would like to do it with FreeBSD, that's why I'm asking. Maybe somebody has a clever idea, which can make it possible on FreeBSD, without the above hassles. Of course what is really needed here is a cluster filesystem, or an NFS server/file system which can solve this problem at its level. > I don't know if this is an option for you, but you can > also put a minimal root file system into the kernel > (md file system), just sufficient to get networking + > AMD running, and mount everything else via NFS. Another Yes, I've also thought of that, but that has drawbacks too. Thanks for the ideas. -- Attila Nagy e-mail: Attila.Nagy@fsn.hu Free Software Network (FSN.HU) phone: +3630 306 6758 http://www.fsn.hu/
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