[ovirt-users] storage redundancy in Ovirt

Mon Apr 17 03:19:41 UTC 2017

Makes sense.
I was trying to set it up, but doesn't work with our staging hardware.
We have old ilo100, I'll try again.
Thanks!
On Sun, Apr 16, 2017 at 8:18 PM Dan Yasny <dyasny at gmail.com> wrote:

> On Sun, Apr 16, 2017 at 11:15 PM, Konstantin Raskoshnyi <
> konrasko at gmail.com> 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 at gmail.com> wrote:
>>
>>> On Sun, Apr 16, 2017 at 11:13 PM, Konstantin Raskoshnyi <
>>> konrasko at gmail.com> 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 at gmail.com> wrote:
>>>>
>>>>> On Sun, Apr 16, 2017 at 7:29 AM, Nir Soffer <nsoffer at redhat.com>
>>>>> wrote:
>>>>>
>>>>>> On Sun, Apr 16, 2017 at 2:05 PM Dan Yasny <dyasny at redhat.com> wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Apr 16, 2017 7:01 AM, "Nir Soffer" <nsoffer at redhat.com> wrote:
>>>>>>>
>>>>>>> On Sun, Apr 16, 2017 at 4:17 AM Dan Yasny <dyasny at gmail.com> 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 at gmail.com> 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 at upx.com> 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 at gmail.com>:
>>>>>>>>>>
>>>>>>>>>>> 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 at upx.com> 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 at gmail.com>:
>>>>>>>>>>>>
>>>>>>>>>>>>> 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 at ovirt.org
>>>>>>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> _______________________________________________
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>>>>>>>>> http://lists.ovirt.org/mailman/listinfo/users
>>>>>>>>>
>>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Users mailing list
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>>>>>>>
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