[ovirt-users] storage redundancy in Ovirt

Mon Apr 17 03:29:39 UTC 2017

Oh, fence agent works fine if I select ilo4,
Thank you for your help!

On Sun, Apr 16, 2017 at 8:22 PM Dan Yasny <dyasny at gmail.com> wrote:

> On Sun, Apr 16, 2017 at 11:19 PM, Konstantin Raskoshnyi <
> konrasko at gmail.com> wrote:
>
>> 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!
>>
>>
> It is absolutely necessary for any HA to work properly. There's of course
> the "confirm host has been shutdown" option, which serves as an override
> for the fence command, but it's manual
>
>
>> 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
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> _______________________________________________
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>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>
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>>>>>>>>>>>
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>>>>>>>>>
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