Re: [ovirt-users] storage redundancy in Ovirt

On Sun, Apr 16, 2017 at 11:15 PM, Konstantin Raskoshnyi < konrasko(a)gmail.com&gt; wrote: > Fence agent under each node? > When you configure a host, there's the power management tab, where you need to enter the bmc details for the host. If you don't have fencing enabled, how do you expect the system to make sure a host running a service is actually down (and it is safe to start HA services elsewhere), and not, for example, just unreachable by the engine? How do you avoid a splitbraid -> SBA ? > > On Sun, Apr 16, 2017 at 8:14 PM Dan Yasny <dyasny(a)gmail.com&gt; wrote: > >> On Sun, Apr 16, 2017 at 11:13 PM, Konstantin Raskoshnyi < >> konrasko(a)gmail.com&gt; wrote: >> >>> "Corner cases"? >>> I tried to simulate crash of SPM server and ovirt kept trying to >>> reistablished connection to the failed node. >>> >> >> Did you configure fencing? >> >> >>> >>> >>> On Sun, Apr 16, 2017 at 8:10 PM Dan Yasny <dyasny(a)gmail.com&gt; wrote: >>> >>>> On Sun, Apr 16, 2017 at 7:29 AM, Nir Soffer <nsoffer(a)redhat.com&gt; >>>> wrote: >>>> >>>>> On Sun, Apr 16, 2017 at 2:05 PM Dan Yasny <dyasny(a)redhat.com&gt; wrote: >>>>> >>>>>> >>>>>> >>>>>> On Apr 16, 2017 7:01 AM, "Nir Soffer" <nsoffer(a)redhat.com&gt; wrote: >>>>>> >>>>>> On Sun, Apr 16, 2017 at 4:17 AM Dan Yasny <dyasny(a)gmail.com&gt; wrote: >>>>>> >>>>>>> When you set up a storage domain, you need to specify a host to >>>>>>> perform the initial storage operations, but once the SD is defined, it's >>>>>>> details are in the engine database, and all the hosts get connected to it >>>>>>> directly. If the first host you used to define the SD goes down, all other >>>>>>> hosts will still remain connected and work. SPM is an HA service, and if >>>>>>> the current SPM host goes down, SPM gets started on another host in the DC. >>>>>>> In short, unless your actual NFS exporting host goes down, there is no >>>>>>> outage. >>>>>>> >>>>>> >>>>>> There is no storage outage, but if you shutdown the spm host, the >>>>>> spm host >>>>>> will not move to a new host until the spm host is online again, or >>>>>> you confirm >>>>>> manually that the spm host was rebooted. >>>>>> >>>>>> >>>>>> In a properly configured setup the SBA should take care of that. >>>>>> That's the whole point of HA services >>>>>> >>>>> >>>>> In some cases like power loss or hardware failure, there is no way to >>>>> start >>>>> the spm host, and the system cannot recover automatically. >>>>> >>>> >>>> There are always corner cases, no doubt. But in a normal situation. >>>> where an SPM host goes down because of a hardware failure, it gets fenced, >>>> other hosts contend for SPM and start it. No surprises there. >>>> >>>> >>>>> >>>>> Nir >>>>> >>>>> >>>>>> >>>>>> >>>>>> Nir >>>>>> >>>>>> >>>>>>> >>>>>>> On Sat, Apr 15, 2017 at 1:53 PM, Konstantin Raskoshnyi < >>>>>>> konrasko(a)gmail.com&gt; wrote: >>>>>>> >>>>>>>> Hi Fernando, >>>>>>>> I see each host has direct connection nfs mount, but yes, if main >>>>>>>> host to which I connected nfs storage going down the storage becomes >>>>>>>> unavailable and all vms are down >>>>>>>> >>>>>>>> >>>>>>>> On Sat, Apr 15, 2017 at 10:37 AM FERNANDO FREDIANI < >>>>>>>> fernando.frediani(a)upx.com&gt; wrote: >>>>>>>> >>>>>>>>> Hello Konstantin. >>>>>>>>> >>>>>>>>> That doesn`t make much sense make a whole cluster depend on a >>>>>>>>> single host. From what I know any host talk directly to NFS Storage Array >>>>>>>>> or whatever other Shared Storage you have. >>>>>>>>> Have you tested that host going down if that affects the other >>>>>>>>> with the NFS mounted directlly in a NFS Storage array ? >>>>>>>>> >>>>>>>>> Fernando >>>>>>>>> >>>>>>>>> 2017-04-15 12:42 GMT-03:00 Konstantin Raskoshnyi < >>>>>>>>> konrasko(a)gmail.com&gt;: >>>>>>>>> >>>>>>>>>> In ovirt you have to attach storage through specific host. >>>>>>>>>> If host goes down storage is not available. >>>>>>>>>> >>>>>>>>>> On Sat, Apr 15, 2017 at 7:31 AM FERNANDO FREDIANI < >>>>>>>>>> fernando.frediani(a)upx.com&gt; wrote: >>>>>>>>>> >>>>>>>>>>> Well, make it not go through host1 and dedicate a storage >>>>>>>>>>> server for running NFS and make both hosts connect to it. >>>>>>>>>>> In my view NFS is much easier to manage than any other type of >>>>>>>>>>> storage, specially FC and iSCSI and performance is pretty much the same, so >>>>>>>>>>> you won`t get better results other than management going to other type. >>>>>>>>>>> >>>>>>>>>>> Fernando >>>>>>>>>>> >>>>>>>>>>> 2017-04-15 5:25 GMT-03:00 Konstantin Raskoshnyi < >>>>>>>>>>> konrasko(a)gmail.com&gt;: >>>>>>>>>>> >>>>>>>>>>>> Hi guys, >>>>>>>>>>>> I have one nfs storage, >>>>>>>>>>>> it's connected through host1. >>>>>>>>>>>> host2 also has access to it, I can easily migrate vms between >>>>>>>>>>>> them. >>>>>>>>>>>> >>>>>>>>>>>> The question is - if host1 is down - all infrastructure is >>>>>>>>>>>> down, since all traffic goes through host1, >>>>>>>>>>>> is there any way in oVirt to use redundant storage? >>>>>>>>>>>> >>>>>>>>>>>> Only glusterfs? >>>>>>>>>>>> >>>>>>>>>>>> Thanks >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>>>>> _______________________________________________ >>>>>>>>>>>> Users mailing list >>>>>>>>>>>> Users(a)ovirt.org >>>>>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>>>>>>> >>>>>>>>>>>> >>>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> Users mailing list >>>>>>>> Users(a)ovirt.org >>>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>>> >>>>>>>> >>>>>>> _______________________________________________ >>>>>>> Users mailing list >>>>>>> Users(a)ovirt.org >>>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>>> >>>>>> >>>>>> _______________________________________________ >>>>>> Users mailing list >>>>>> Users(a)ovirt.org >>>>>> http://lists.ovirt.org/mailman/listinfo/users >>>>>> >>>>>> >>>>>>