[ovirt-users] storage redundancy in Ovirt

FERNANDO FREDIANI fernando.frediani at upx.com
Mon Apr 17 13:12:54 UTC 2017


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 ?

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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