Re: [ovirt-devel] Sanlock fencing reservations

From: "Dan Kenigsberg" <danken(a)redhat.com&gt; To: "Saggi Mizrahi" <smizrahi(a)redhat.com&gt;, nsoffer(a)redhat.com Cc: devel(a)ovirt.org, "David Teigland" <teigland(a)redhat.com&gt; Sent: Wednesday, April 16, 2014 10:33:39 AM Subject: Re: Sanlock fencing reservations On Wed, Feb 26, 2014 at 11:14:33AM -0500, Saggi Mizrahi wrote: > I've recently been introduced to the this feature and I was wondering is > this really > the correct way to go for solving this particular problem. > > My main issue is with making two unrelated flow dependent. > By pushing this into the existing sanlock data structures you limit > yourself > in the future from changing either to optimize or even solve problems for a > single use case. > > Having an independent daemon to perform this task will give more room as to > how to implement the feature. Saggi, are you thinking about something similar to fence_sanlockd http://linux.die.net/man/8/fence_sanlockd and its client fence_sanlock? Using them, instead of reimplementing parts of them within Vdsm, seem reasonable in first glance. However http://www.ovirt.org/Features/Sanlock_Fencing#Why_not_use_fence_sanlockd.3F claim that it wastes 2G of storage and requires explicit master domain upgrade. Nir, could you explain why so much space is required by sanlockd? Can it be configured to use smaller area?