Finally I have found notes on HA NFS on SLES9 - http://www.gatsby.ucl.ac.uk/~johnp/compute/ha-nfs-sles9.html There are more info on this topic, for instance http://linux-ha.org/DRBD/NFS Suddenly I realized that previous designer was following these guidelines :-) I have found that all documents suggest to have both primary and standby hosts configured as NFS server only and start/stop server processes when role is changed. This way /var/lib/nfs, even relocating on DRBD partition, is always available on NFS server startup. So, it is OK to have /var/lib/nfs as link to the folder on DRBD partition. What I have different is that my system breaks rule of acting as NFS servers only: standby host acts as NFS client until it becomes primary, then it should act as server. I'll summarize info here: "server" is DNS record, resolved into IP of the primary host. HOST1, primary: /dev/drbd is mounted as /storage /storage is exported server:/storage is mounted as /some/path /var/lib/nfs is link to the /some/path/var/lib/nfs and is available HOST2: /dev/drbd is not mounted, /storage is empty server:/storage is mounted as /some/path /var/lib/nfs is link to the /some/path/var/lib/nfs and is empty So, due to this /some/path mount existing on both hosts I have problem with initialization of the kstatd on the standby host, where /var/lib/nfs looks like empty folder. I have requirement for having /some/path on both hosts, so I can't fallback to guidelines advices. I need to do NFS client became NFS server somehow. There should be some runtime re-initialization. This is what I'm looking for. Could someone comment on this? Is there any way to do so? Or any better solution? By the way, browsing sources I have found that one can set nsm_use_kstatd to 1 on lockd exit, then initialization will be successful on next mount or export attempts. I think someone can find it useful so created patch. Unfortunately I don't have neither time nor enough code knowledge. In my case this proposal has drawback - lockd exits when all mounts are unmounted only, so I have to umount /some/path first and then mount it back. It can be painful as soon as some files can be opened by local user and umount will complain with it's usual "device is busy". Also I was thinking about having /var/lin/nfs locally, separate for each host, so kstatd will be initialized always, but how do I share vital info about clients then? I have found it to be dead-end. Best regards Vladimir Vlasov -----Original Message----- From: Vlasov, Vladimir Sent: Thursday, January 26, 2012 4:14 PM To: 'NeilBrown' Cc: linux-nfs@xxxxxxxxxxxxxxx Subject: RE: Re-init lockd and kstatd in runtime. Yes, it is SLES10 SP3 and I'm a customer. I'm not sure that Novell can help me, I expect the same proposal from them - "just make sure that /var/lib/nfs is available on startup". I'm not satisfied with this because I have some kind of high availability system built with two Linux hosts. Hosts share DRBD partition and one acting as primary exports, for instance /some/path. As soon as primary host fails, another one becomes primary and exports /some/path. There are more hosts on the network, they mount: server:/some/path where "server" is resolved to the IP of current primary host which currently exports path. So, in order to keep and overtake data about clients, /var/lib/nfs is replaced with link and points to /some/path/var/lib/nfs. If You don't familiar with DRBD then the most important thing You should know is that it is available for R/W on primary host only. So, on primary host DRBD is R/W, /var/lib/nfs is available and kstatd starts. On another host DRBD is NOT R/W, /var/lib/nfs is empry and kstatd doesn't start. This is why I'm looking for how do I re-init it at any time. I was looking for guidelines of using NFS in clusters but didn't found anything useful. Best regards Vladimir Vlasov -----Original Message----- From: NeilBrown [mailto:neilb@xxxxxxx] Sent: Thursday, January 26, 2012 3:41 PM To: Vlasov, Vladimir Cc: linux-nfs@xxxxxxxxxxxxxxx Subject: Re: Re-init lockd and kstatd in runtime. On Thu, 26 Jan 2012 11:15:02 +0000 "Vlasov, Vladimir" <vvlasov@xxxxxxx> wrote: > Hi. > > I'm wondering if there is any way to re-init lockd and kstatd after startup? > > Look, in svc.c static variable nsm_use_kstatd is set to 1. > Then, if nsm_kernel_statd_init() returns error, nsm_use_kstatd is set to 0. > And we end up without kstatd. > > Lockd will exit as soon as last NFS mount is unmounted and on next mount attempt lockd() in svc.c will be called again, but nsm_use_kstatd is 0 already and kstatd init will be skipped. > > So, looks like if /var/lib/nfs/state is missed on host startup, there is no way to recover and tell kernel init kstatd later on demand. Or? This would be SLES10 - correct? I suggest you simply make sure /var/lib/nfs/state is not missing at startup. The issue sounds vaguely familiar ... maybe it is fixed in SLES10-SP4... What release are you running? Are you a SLES customer? If you are, you would be better off logging a support request on the SUSE bugzilla (bugzilla.novell.com). NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
