Re: [one-dev] Live migration / recovery - suggestions

[David Macleod]

Hi Gareth, Jaime   Why can't the recovery be handled by the migrate script? You can distribute your own custom vmm driver so that it doesn't get overwritten by the updates. That's how I wrote my add-on, I also have the need to recover from a migrate fail.   Regards, David >>> Jaime Melis <jme...@opennebula.org> 2014/01/20 12:43 PM >>> Hi Gareth, we've been studying your proposal, and even though we agree with what you say we aren't 100% convinced with this solution. The issues with the proposal are the following: - As long as it's possible, we'd like to keep separate the main opennebula code and the addons. In this case it means that we are not very comfortable with point 3: adding addon-specific code to the main repository. - The proposed solution only solves the "migrate" issue, but other addons will have potentially issues with other scripts, and not necessarily with the "CleanUp" part of the "ssh_exec_and_log". We would like to find a more general solution. We are still thinking about this, we definitely want to solve this issue, so if you (or anyone else) has any ideas, please let us know. cheers, Jaime On Tue, Jan 14, 2014 at 2:23 PM, Gareth Bult <gar...@linux.co.uk> wrote: Hey Guys, I've done a little work on the migration script - this is what I've done here .. - be nice if something similar could be implemented @ source .. ? 1. ssh_exec_and_log (generic change - this could be useful elsewhere..) modify as follows; function ssh_exec_and_log { message=$2 cleanup=$3 # ++ EXEC_LOG_ERR=`$1 2>&1 1>/dev/null` EXEC_LOG_RC=$? if [ $EXEC_LOG_RC -ne 0 ]; then log_error "Command \"$1\" failed: $EXEC_LOG_ERR" if [ ! -z $cleanup ]; then # ++ $cleanup # ++ fi # ++ if [ -n "$2" ]; then error_message "$2" else error_message "Error executing $1: $EXEC_LOG_ERR" fi return $EXEC_LOG_RC fi } i.e. allow a third parameter which is a function to call if the exec fails. 2. migrate (for my vdc code), add "CleanUp" as a last parameter on the exec_and_log on the last line ssh_exec_and_log "virsh --connect $LIBVIRT_URI migrate --live $deploy_id $QEMU_PROTOCOL://$dest_host/system" \ "Could not migrate $deploy_id to $dest_host" CleanUp 3. Then add the following function to migrate; function CleanUp { VDC=$(dirname $0)/../../../vdc-nebula if [ -d "${VDC}" ]; then ${VDC}/remotes/tm/vdc/postmigrate_fail ${deploy_id} ${dest_host} fi } Cleanup could be extended for other storage options ... ?? I guess ideally you would pass the driver through and CleanUp would become completely generic and postmigrate_fail would become just another standard routine?? hth Gareth. -- Gareth Bult “The odds of hitting your target go up dramatically when you aim at it.” See the status of my current project at http://vdc-store.com From: "Ruben S. Montero" <rsmont...@opennebula.org> To: "Gareth Bult" <gar...@linux.co.uk> Cc: dev@lists.opennebula.org Sent: Monday, 13 January, 2014 3:41:50 PM Subject: Re: [one-dev] Live migration / recovery Totally agree, in fact we've seen this in the past. This is fairly easy to add, one_vmm_exec.rb includes a pseudo-dsl to specify the actions, each action includes a fail action. Looking at the code we have also to roll-back the networking configuration on the target host. Added a new issue for this. In the meantime we can just use the previous workaround. http://dev.opennebula.org/issues/2633 On Mon, Jan 13, 2014 at 2:59 PM, Gareth Bult <gar...@linux.co.uk> wrote: Ok, this almost seems too easy ... :) What I was trying to avoid was more tweaking of ON files when installing VDC. The issue I see is that each time someone upgraded ON, they will potentially have a chain of small patches to apply ... if I supply a few small patches based on "if <vdc installed> - do something extra" would you include these in the stock scripts?? Gareth. -- Gareth Bult “The odds of hitting your target go up dramatically when you aim at it.” See the status of my current project at http://vdc-store.com From: "Ruben S. Montero" <rsmont...@opennebula.org> To: "Gareth Bult" <gar...@linux.co.uk> Cc: dev@lists.opennebula.org Sent: Sunday, 12 January, 2014 10:36:30 PM Subject: Re: [one-dev] Live migration / recovery Hi Gareth As the migrate script can be easily updated we do not provide any hook for that. I'd go to kvm/migrate, and do a simple if [ $? ... after the virsh command to kill the cache on the target host. Cheers Ruben On Thu, Dec 19, 2013 at 12:54 PM, Gareth Bult <gar...@linux.co.uk> wrote: Hi, I implemented live migration for the VDC driver a few weeks back and on the whole it seems to work quite well. The "premigrate" script creates a cache instance on the target server and puts the source cache into proxy mode, then the "postmigrate" script kills the original cache instance. Problem :: if the migration fails, I'm left with a running cache on both the source and target servers, with the source cache in proxy mode. I have a 1-line CLI command to revert the issue, but I need to hook into the system in order to call it. How to do I do this, I guess effectively I need something like "postmigrate_fail" .. ??? tia Gareth. -- Gareth Bult “The odds of hitting your target go up dramatically when you aim at it.” _______________________________________________ Dev mailing list Dev@lists.opennebula.org http://lists.opennebula.org/listinfo.cgi/dev-opennebula.org -- -- Ruben S. Montero, PhD Project co-Lead and Chief Architect OpenNebula - Flexible Enterprise Cloud Made Simple www.OpenNebula.org | rsmont...@opennebula.org | @OpenNebula -- -- Ruben S. Montero, PhD Project co-Lead and Chief Architect OpenNebula - Flexible Enterprise Cloud Made Simple www.OpenNebula.org | rsmont...@opennebula.org | @OpenNebula _______________________________________________ Dev mailing list Dev@lists.opennebula.org http://lists.opennebula.org/listinfo.cgi/dev-opennebula.org -- Jaime Melis Project Engineer OpenNebula - Flexible Enterprise Cloud Made Simple www.OpenNebula.org | jme...@opennebula.org -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. Please consider the environment before printing this email. -- This message is subject to the CSIR's copyright terms and conditions, e-mail legal notice, and implemented Open Document Format (ODF) standard. The full disclaimer details can be found at http://www.csir.co.za/disclaimer.html. This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean. Please consider the environment before printing this email.

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