16 Jul
2013
16 Jul
'13
8:54 p.m.
Doron Fediuck wrote: > ----- Original Message ----- > | From: "Itamar Heim" <iheim@redhat.com> > | To: "Doron Fediuck" <dfediuck@redhat.com> > | Cc: "Christian Kolquist" <ckolquist@rgmadvisors.com>, users@ovirt.org, "Dan Kenigsberg" <danken@redhat.com> > | Sent: Tuesday, July 16, 2013 3:04:11 PM > | Subject: Re: [Users] SPM and VM migrations > | > | On 07/08/2013 02:07 PM, Doron Fediuck wrote: > | > > | > ----- Original Message ----- > | > | From: "Christian Kolquist" <ckolquist@rgmadvisors.com> > | > | To: users@ovirt.org > | > | Sent: Tuesday, July 2, 2013 11:01:55 PM > | > | Subject: [Users] SPM and VM migrations > | > | > | > | I currently have an issue where when we migrate more than one VM from the > | > | host that is the SPM to another host it will cause connectivity to the > | > | SPM > | > | Host to fail which the ovirt engine then sees the host being down. It > | > | then > | > | reboots the SPM Host and stops all of the VM's running on there. > | > | > | > | > | > | Our setup > | > | > | > | Nodes: Fedora 18 > | > | em1: ovirtmgmt (mgmt, storage and migrations) > | > | em2: VM network trunks > | > | > | > | Engine: Fedora 17 (will be upgrading that to fedora 18 shortly) > | > | > | > | Both NICS are 1 GB. The storage is NFS which is on the same VLAN and > | > | subnet > | > | as the hosts. The ovirt-engine is on a standalone server but is NOT on > | > | the > | > | same vlan/subnet yet. > | > | > | > | Is this normal behavior for the SPM to have issue when migrating hosts to > | > | and > | > | from it? I don't have any further network interfaces to add to the hosts > | > | at > | > | this time (we are planning on adding a 2x 10GB card to each node in the > | > | future but we don't have that option at this time). Is there anyway to > | > | limit > | > | the number of active migrations and have the migrations be a lower > | > | priority > | > | traffic than others? > | > | > | > | > | > | Thanks > | > | Christian > | > | > | > | > | > | --------------------------------------------------------------- > | > | This email, along with any attachments, is confidential. If you > | > | believe you received this message in error, please contact the > | > | sender immediately and delete all copies of the message. > | > | Thank you. > | > | > | > > | > Hi Christian, > | > Apparently the migration is eating up your bandwidth. > | > Currently it is possible to hard-limit the migration using > | > The /usr/share/doc/<vdsm-version>/vdsm.conf.sample file with > | > > | > # Maximum bandwidth for migration, in mbps, 0 means libvirt's default > | > (30mbps?). > | > # migration_max_bandwidth = 0 > | > | why not change this default from 0 to something more defensive? > | > > IIRC the limitation has a very bad effect in most cases, and it may > also get you to a point where the migration process does not converge. > > | > > | > In the coming oVirt 3.3 we should be able to handle this by separating > | > the migration network, and then use- > | > http://www.ovirt.org/Features/Network_QoS > | > > | > Doron > | > I asked about this parameter the other day and have used it on two hosts sofar BUT is has an unmentioned sideeffect. There are two parameters: - migration_max_bandwidth - max_outgoing_migrations I thought that setting the first to 85 would be enough but it isn't. The settings mean the following: If max_outgoing_migrations is set to 2 or higher than you the end result will be max_outgoing_migrations*migration_max_bandwidth, meaning that with anything higher than 1 in my case will saturated my 1G line. So max_outgoing_migrations=3 and migration_max_bandwidth=70 will consume 210Mb if the line has that capacity if you select more than 3 VMs to migratie. So migration_max_bandwidth is PER VM and not an absolute. 0 means take as much as you can not 30 since 1 VM will saturate 1G easily if its a big one. In our case we will probably go for 1 VM at a time but at 85-90M since our use case is usually 1 VM at a time. Joop