[ovirt-users] storage redundancy in Ovirt
FERNANDO FREDIANI
fernando.frediani at upx.com
Mon Apr 17 14:31:34 UTC 2017
Thanks for the clarification Adam.
That makes total sense.
Reagrds
Fernando
On 17/04/2017 11:28, Adam Litke wrote:
>
>
> On Mon, Apr 17, 2017 at 9:12 AM, FERNANDO FREDIANI
> <fernando.frediani at upx.com <mailto:fernando.frediani at upx.com>> wrote:
>
> Should I understand then that fecing is not mandatory, just
> advised and there are no downtimes to the rest of the cluster if a
> pending manual action has to be done to confirm a host has been
> rebooted in order to move the SPM to another live host. Perhaps
> only effect is not be able to add new hosts and connect to storage
> or something ?
>
> A missing SPM will not affect existing VMs. Running VMs (on hosts
> other than the SPM host) will continue to run normally and you can
> even start existing VMs. Without an SPM you will not be able to
> manipulate the storage (Add/remove domains, add/remove disks, migrate
> disks, etc).
>
> Fernando
>
> On 17/04/2017 10:06, Nir Soffer wrote:
>> On Mon, Apr 17, 2017 at 8:24 AM Konstantin Raskoshnyi
>> <konrasko at gmail.com <mailto:konrasko at gmail.com>> wrote:
>>
>> But actually, it didn't work well. After main SPM host went
>> down I see this
>> Screen Shot 2017-04-16 at 10.22.00 PM.png
>>
>> 2017-04-17 05:23:15,554Z ERROR
>> [org.ovirt.engine.core.vdsbroker.irsbroker.IrsProxy]
>> (DefaultQuartzScheduler5)
>> [4dcc033d-26bf-49bb-bfaa-03a970dbbec1] SPM Init: could not
>> find reported vds or not up - pool: 'STG' vds_spm_id: '1'
>> 2017-04-17 05:23:15,567Z INFO
>> [org.ovirt.engine.core.vdsbroker.irsbroker.IrsProxy]
>> (DefaultQuartzScheduler5)
>> [4dcc033d-26bf-49bb-bfaa-03a970dbbec1] SPM selection - vds
>> seems as spm 'tank5'
>> 2017-04-17 05:23:15,567Z WARN
>> [org.ovirt.engine.core.vdsbroker.irsbroker.IrsProxy]
>> (DefaultQuartzScheduler5)
>> [4dcc033d-26bf-49bb-bfaa-03a970dbbec1] spm vds is non
>> responsive, stopping spm selection.
>>
>> So that means only if BMC is up it's possible to
>> automatically switch SPM host?
>>
>>
>> BMC?
>>
>> If your SPM is no responsive, the system will try to fence it.
>> Did you
>> configure power management for all hosts? did you check that it
>> work? How did you simulate non-responsive host?
>>
>> If power management is not configured or fail, the system cannot
>> move the spm to another host, unless you manually confirm that the
>> SPM host was rebooted.
>>
>> Nir
>>
>>
>> Thanks
>>
>> On Sun, Apr 16, 2017 at 8:29 PM, Konstantin Raskoshnyi
>> <konrasko at gmail.com <mailto:konrasko at gmail.com>> wrote:
>>
>> 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 <mailto:dyasny at gmail.com>> wrote:
>>
>> On Sun, Apr 16, 2017 at 11:19 PM, Konstantin
>> Raskoshnyi <konrasko at gmail.com
>> <mailto: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 <mailto:dyasny at gmail.com>> wrote:
>>
>> On Sun, Apr 16, 2017 at 11:15 PM, Konstantin
>> Raskoshnyi <konrasko at gmail.com
>> <mailto: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
>> <mailto:dyasny at gmail.com>> wrote:
>>
>> On Sun, Apr 16, 2017 at 11:13 PM,
>> Konstantin Raskoshnyi
>> <konrasko at gmail.com
>> <mailto: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
>> <mailto:dyasny at gmail.com>> wrote:
>>
>> On Sun, Apr 16, 2017 at 7:29
>> AM, Nir Soffer
>> <nsoffer at redhat.com
>> <mailto:nsoffer at redhat.com>>
>> wrote:
>>
>> On Sun, Apr 16, 2017 at
>> 2:05 PM Dan Yasny
>> <dyasny at redhat.com
>> <mailto:dyasny at redhat.com>>
>> wrote:
>>
>>
>>
>> On Apr 16, 2017 7:01
>> AM, "Nir Soffer"
>> <nsoffer at redhat.com
>> <mailto:nsoffer at redhat.com>>
>> wrote:
>>
>> On Sun, Apr 16,
>> 2017 at 4:17 AM
>> Dan Yasny
>> <dyasny at gmail.com
>> <mailto: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
>> <mailto: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
>> <mailto: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
>> <mailto: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
>> <mailto: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
>> <mailto: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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> --
> Adam Litke
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