[ovirt-users] Adding FCP - Request for comments

Fri May 22 20:24:38 UTC 2015

----- Original Message -----
> From: "Daniel Helgenberger" <daniel.helgenberger at m-box.de>
> To: "Nir Soffer" <nsoffer at redhat.com>
> Cc: "Fábio Coelho" <fabio.coelho at jfsc.jus.br>, "users" <Users at ovirt.org>
> Sent: Friday, May 22, 2015 11:13:31 PM
> Subject: Re: [ovirt-users] Adding FCP - Request for comments
> 
> 
> 
> On 22.05.2015 21:08, Nir Soffer wrote:
> > ----- Original Message -----
> >> From: "Daniel Helgenberger" <daniel.helgenberger at m-box.de>
> >> To: "Fábio Coelho" <fabio.coelho at jfsc.jus.br>, "users" <Users at ovirt.org>
> >> Sent: Wednesday, May 20, 2015 8:46:01 PM
> >> Subject: Re: [ovirt-users] Adding FCP - Request for comments
> >>
> >>
> >>
> >> On 20.05.2015 19:10, Fábio Coelho wrote:
> >> Hello Fabio,
> >>> Thoughts about Adding Storage Luns
> >>>
> >>> As I am new here, I would appreciate some advice about some actions that
> >>> I
> >>> intend to perform, please read.
> >>>
> >>> I have added a LUN to my cluster and, for that task, I had to restart
> >>> every
> >>> node
> >>> of it. There was no LUNs before, multipathd was stopped and
> >>> multipath.conf
> >>> inexisted. I was able to log in and manually configure multipath.conf, a
> >>> simple
> >>> multipathd start was not enough.
> >> In theory this should have been enough. What puzzles me: Until now
> >> host-deploy always activated multipathd and writes a multipath.conf.
> >>
> >> Here I strongly recommend to blacklist everything and then only white
> >> listing your vendors. Otherwise your error logs fill up and you cannot
> >> connect any USB stick to the host any more ;)
> >>
> >> Then, add RHEV PRIVATE to the second line otherwise it will be
> >> overwritten on every host deploy run.
> >> # RHEV PRIVATE
> >>
> >> blacklist {
> >>           device {
> >>                   vendor "*"
> >>                   product "*"
> >>           }
> >> }
> >
> > This is bad idea. If you want to blacklist all devices, you can add this to
> > vdsm generated configuration.
> What can I add?
> 
> >
> > Vdsm is depending on the defaults set in the "defaults" section.
> 
> I just looked; seems to me this is the default part vdsm is needing?
> 
> defaults {
>      polling_interval        5
>      no_path_retry           fail
>      user_friendly_names     no
>      flush_on_last_del       yes
>      fast_io_fail_tmo        5
>      dev_loss_tmo            30
>      max_fds                 4096
> }

Right, if you have these you should be fine.

> 
> The problem is there is no blacklisting at all in the default
> multipath.conf - at least not in mine.
> 
> I know this is a hard thing to do for a general version of the file
> witch works for anyone. As for my part I have only very specific devices
> / vendors I want to have in my multipah.conf; so I blacklist everything
> and later on add blacklist exceptions like:
> 
> blacklist_exceptions {
>          device {
>                  vendor  "IFT"
>                  product "*"
>          }
> }
> 
> Witch IMHO is (was?) since best practice a long time ago when I created
> my configs.

We try to make it work for everyone without extra configuration, so
we cannot use automatic blacklisting.

My comments was only about multpath.conf without "defaults" section.

Thanks,
Nir

> 
> >
> >>
> >>
> >>
> >> After activating multipathd and editing multipath.conf to your needs you
> >> would actually need to run the 'multipath' command to create the paths.
> >> [1]
> >>
> >> Sometimes you need to rescan the LUNs, though, esp. if you changed sizes
> >> after activating them.
> >>>
> >>> If this wasn't enough, my double NetAPP ( through an Hitachi ) provided
> >>> me
> >>> with
> >>> a not so empty brand new LUN, and the task to add the FCP failed to point
> >>> this.
> >>> Trusting my double, I spent some precious time searching for different
> >>> problems,
> >>> until receiving some guidance and do a simple dd if=/dev/zero to the
> >>> initial
> >>> blocks of the LUN.
> >> IMHO you need to initialize the lun with a partition table at least
> >> (parted). dd will do also.
> >>
> >>>
> >>> Consulting the documentation
> >>> ( http://www.ovirt.org/OVirt_Administration_Guide#Adding_FCP_Storage )
> >>> for
> >>> this
> >>> matters, was not of any help.
> >>>
> >>> So, my questions:
> >>>
> >>> This is the intended behavior? Should I open a ticket?
> >>>
> >>> Should I add a note to documentation to point such behavior? ( i'm about
> >>> to
> >>> )
> >>>
> >> I think this is not ovirts part but rather dm-multipath. My best guess
> >> would be a configuration error on your part?
> >>
> >> [1]
> >> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/DM_Multipath/#mpio_setup
> >>>
> >>> Cheers,
> >>>
> >>> by qoelheX
> >>>
> >>>
> >>> Aviso Legal
> >>>
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> >>> sendo
> >>> o
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> >>> for a
> >>> pessoa autorizada a receber esta mensagem e tendo recebido a mesma por
> >>> engano,
> >>> favor apagá-la imediatamente. A JFSC considera opiniões, conclusões e
> >>> outras
> >>> informações não oficiais de responsabilidade do usuário deste serviço.
> >>>
> >>
> >> --
> >> Daniel Helgenberger
> >> m box bewegtbild GmbH
> >>
> >> P: +49/30/2408781-22
> >> F: +49/30/2408781-10
> >>
> >> ACKERSTR. 19
> >> D-10115 BERLIN
> >>
> >>
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> >>
> >
> 
> --
> Daniel Helgenberger
> m box bewegtbild GmbH
> 
> P: +49/30/2408781-22
> F: +49/30/2408781-10
> 
> ACKERSTR. 19
> D-10115 BERLIN
> 
> 
> www.m-box.de  www.monkeymen.tv
> 
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