On 10/16/2011 07:21 AM, Joey L wrote: > Digimer - thanks for you input - you saved me a ton of time!!! > I did look at your tutorial -- great stuff BTW. Thank you. :) > I thought fencing was an option because I setup RH cluster about 5 > years ago and I thought I did not do it then..and further in the RHEL > Cluster Administrator had points that it was optional -can not find > the url right now. but have pdf and it says: Maybe in very old versions, but not under EL5 or EL6. Like I said, RGManager uses DLM and DLM blocks on fence and fence triggers as soon as a node goes quiet, regardless of if there is a fence device or not. > "If a cluster node is configured to be fenced by an integrated fence > device, disable ACPI Soft-Off for > that node. Disabling ACPI Soft-Off allows an integrated fence device > to turn off a node immediately > and completely rather than attempting a clean shutdown (for example, > shutdown -h now). > Otherwise, if ACPI Soft-Off is enabled, an integrated fence device can > take four or more seconds to > turn off a node (refer to note that follows). In addition, if ACPI > Soft-Off is enabled and a node panics > or freezes during shutdown, an integrated fence device may not be able > to turn off the node. Under > those circumstances, fencing is delayed or unsuccessful. Consequently, > when a node is fenced > with an integrated fence device and ACPI Soft-Off is enabled, a > cluster recovers slowly or requires > administrative intervention to recover " This helps speed up recovery. However, I prefer to leave it on an accept the 4 seconds delta because I find ACPI soft-off is very handy. In the end though, the decision depends on your needs. > But not looking to argue this point at all - i remember that when i > did set it up it was indeed more stable like you state. > My Memory is getting old :) Fencing <3 > About pacemaker -- > Do I need fencing hardware as well ?? Short answer; Yes. Long answer, you can disable stonith. However, that is always a tremendous risk because you set yourself up for a bad day if the cluster is allowed to reconfigure around a blocked node that eventually unblocks. I *strongly* advice against it. Strictly speaking though; No. > I just got 2 servers and a regular switch - i think it netgear. > Like I said earlier - just want the 2 boxes to back up each other. What you want doesn't really preclude the need to build a proper cluster. :) > I have mysql, apache, asterisk, dns and nfs client running on them - > can i do anything with pacemaker ?? Pacemaker and Red Hat cluster will both do this just fine. > I should mention that I am using software raid but will probably need > to change to hardware raid in near future. The cluster doesn't care. > I would like to use the mysql replication feature -- if possible. This is a well tested and used configuration. You should have no trouble getting help. > thanks for your insight and help. > > mjh My pleasure. :) -- Digimer E-Mail: digimer@xxxxxxxxxxx Freenode handle: digimer Papers and Projects: http://alteeve.com Node Assassin: http://nodeassassin.org "At what point did we forget that the Space Shuttle was, essentially, a program that strapped human beings to an explosion and tried to stab through the sky with fire and math?" -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
