<div>Hi,</div> <div> </div> <div>From my understanding, any change request (lv, vg, pv...) should be blocked as long as a lock is held by another alive node in the cluster.</div> <div> </div> <div>I mean the "exclusive flag" was here at the origin to address this. </div> <div> </div> <div>I think there is a sort of misconcept in LVM2 may be due to the fact that for many people assume a cluster is necessarly a "share-everything" infrastructure (a la VMS).</div> <div> </div> <div>This is the good approach for clustering file servers (NFS, CIFS), web servers, etc... where one would take advantage of load balancing user sessions accross multiple nodes.</div> <div> </div> <div>The other need for clustering is to run "mono instance" databases that are not by concept (except Oracle RAC) designed to run accross multiple nodes.</div> <div> </div> <div>In this case, only one node is holding the database instance with all of its storage, and putting it on a "share everything" cluster based on a Cluster filesystem (GFS) would imply :</div> <div> </div> <div> - performance penalty: each storage IO having to request the FS lock manager to be executed</div> <div> --> managing the locks at a lower level (VG and LV) wouldn't imply so as one the VG is exclusively activated no other node can remove the lock, every IO being done on a regular FS (ext3 for instance) without having to manage any kind of locks</div> <div> - Security issue : To bypass this lock mechanism, one should start the clustered FS without locks, but this will certainly lead to FS corruption.</div> <div> </div> <div>Brem</div> <div>2009/7/28, Xinwei Hu <<a href="mailto:hxinwei@gmail.com">hxinwei@gmail.com</a>>:</div> <blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi Brem, I guess the cause of the problem is using 'lvchange -ay'. Clvmd actually does lock conversion underlying. So when you tried 'lvchange -ay', the exclusive lock will be converted to an non-exclusive lock. And that means the second try will success anyway. 2009/7/28 brem belguebli <<a href="mailto:brem.belguebli@gmail.com">brem.belguebli@gmail.com</a>>: > Hi Rafael, > On RHEL 5.3, locks thru DLM aren't reliable all the time, I've been able to > activate a VG on a node of the cluster even if it was already activated > exclusively on another node. > Also, I've been able to activate a LV on a node not holding the exclusive > lock on the VG by typing 2 times lvchange -a y /dev/VGX/lvoly . > First try lvchange tells you there is a lock, second try activates it. > Checking dlm debug (mount -t debugfs debug /debug) /debug/dlm/clvmd_locks > gives a lock for nodeid 0 .... > Brem > > 2009/7/27 Rafael Micó Miranda <<a href="mailto:rmicmirregs@gmail.com">rmicmirregs@gmail.com</a>> >> >> Hi Brem >> >> So, does it work successfully? I made some testing before I submitted it >> to the list and AFAIK i found no errors. >> >> What do you mean exactly with "some CLVM strange behaviours"? Could you >> be more specific? >> >> I'm not subscribed to linux-lvm, please keep us informed through this >> list. >> >> Thanks in advance. Cheers, >> >> Rafael >> >> El lun, 27-07-2009 a las 21:02 +0200, brem belguebli escribió: >> > Hi Rafael, >> > >> > It works fine, well at least when not hiting some CLVM strange >> > behaviours, that I'm able to replay by hand, so your script is >> > allright. >> > >> > I'll post to linux-lvm what I could see. >> > >> > Brem >> > >> > >> > 2009/7/21, brem belguebli <<a href="mailto:brem.belguebli@gmail.com">brem.belguebli@gmail.com</a>>: >> > Hola Rafael, >> > >> > Thanks a lot, that'll avoid me going from scratch. >> > >> > I'll have a look at them and keep you updated. >> > >> > Brem >> > >> > >> > >> > 2009/7/21, Rafael Micó Miranda <<a href="mailto:rmicmirregs@gmail.com">rmicmirregs@gmail.com</a>>: >> > Hi Brem, >> > >> > El mar, 21-07-2009 a las 16:40 +0200, brem belguebli >> > escribió: >> > > Hi, >> > > >> > > That's what I 'm trying to do. >> > > >> > > If you mean lvm.sh, well, I've been playing with it, >> > but it does some >> > > "sanity" checks that are wierd >> > > 1. It expects HA LVM to be setup (why such >> > check if we want to >> > > use CLVM). >> > > 2. it exits if it finds a CLVM VG (kind of >> > funny !) >> > > 3. it exits if the lvm.conf is newer >> > than /boot/*.img (about this >> > > one, we tend to prevent the cluster from >> > automatically >> > > starting ...) >> > > I was looking to find some doc on how to write my >> > own resources, ie >> > > CLVM resource that checks if the vg is clustered, if >> > so by which node >> > > is it exclusively held, and if the node is down to >> > activate >> > > exclusively the VG. >> > > >> > > If you have some good links to provide me, that'll >> > be great. >> > > >> > > Thanks >> > > >> > > >> > > 2009/7/21, Christine Caulfield >> > <<a href="mailto:ccaulfie@redhat.com">ccaulfie@redhat.com</a>>: >> > > On 07/21/2009 01:11 PM, brem belguebli >> > wrote: >> > > Hi, >> > > When creating the VG by default >> > clustered, you >> > > implicitely assume that >> > > it will be used with a clustered FS >> > on top of it (gfs, >> > > ocfs, etc...) >> > > that will handle the active/active >> > mode. >> > > As I do not intend to use GFS in >> > this particular case, >> > > but ext3 and raw >> > > devices, I need to make sure the vg >> > is exclusively >> > > activated on one >> > > node, preventing the other nodes to >> > access it unless >> > > it is the failover >> > > procedure (node holding the VG >> > crashed) and then re >> > > activate it >> > > exclusively on the failover node. >> > > Thanks >> > > >> > > >> > > In that case you probably ought to be using >> > rgmanager to do >> > > the failover for you. It has a script for >> > doing exactly >> > > this :-) >> > > >> > > Chrissie >> > > >> > > >> > > -- >> > > Linux-cluster mailing list >> > > <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> >> > > >> > <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> >> > > >> > > >> > > -- >> > > Linux-cluster mailing list >> > > <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> >> > > >> > <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> >> > >> > Please, check this link: >> > >> > >> > <a href="https://www.redhat.com/archives/cluster-devel/2009-June/msg00020.html">https://www.redhat.com/archives/cluster-devel/2009-June/msg00020.html</a> >> > >> > I found exactly the same problem as you, and i >> > developed the >> > "lvm-cluster.sh" script to solve the needs I had. You >> > can find the >> > script on the last message of the thread. >> > >> > I submitted it to make it part of the main project, >> > but i have no news >> > about that yet. >> > >> > I hope this helps. >> > >> > Cheers, >> > >> > Rafael >> > >> > -- >> > Rafael Micó Miranda >> > >> > -- >> > Linux-cluster mailing list >> > <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> >> > <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> >> > >> > >> > -- >> > Linux-cluster mailing list >> > <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> >> > <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> >> -- >> Rafael Micó Miranda >> >> -- >> Linux-cluster mailing list >> <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> >> <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> > > > -- > Linux-cluster mailing list > <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> > <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> > -- Linux-cluster mailing list <a href="mailto:Linux-cluster@redhat.com">Linux-cluster@redhat.com</a> <a href="https://www.redhat.com/mailman/listinfo/linux-cluster">https://www.redhat.com/mailman/listinfo/linux-cluster</a> </blockquote>