Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Chris Adams
Once upon a time, James Michels  said:
> I guess you mean the 'iSCSI multipath' sub-tab under the 'Datacenters' tab.
> There you can assign one or more networks to a iSCSI backend. In my opinion
> you cannot have more than one interface within the same network segment to
> do multipath, as you would have connectivity issues (not sure if ovirt
> restricts creating two overlapping networks)

The way I did it on a test 3.6 cluster was to create two networks in
oVirt, "storage1" and "storage2".  I assigned both networks to the
hosts, connected to different NICs, and gave each an IP (in the iSCSI
subnet).  Then I could set up the iSCSI multipath in the oVirt data
center.  This seems weird/wrong, and I'm not sure oVirt actually
configured both NICs in multipath.

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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Chris Adams
Once upon a time, Yaniv Kaul  said:
> BTW, having two IPs on a single subnet is not a great idea - it usually
> mean you have a SPOF somewhere (the switch perhaps?).

Two NICs on the server, two NICs on the iSCSI target, each with an IP
per NIC, and connected to two switches in between (either stacked or
trunked).  No SPOF.

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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Yaniv Kaul
On Thu, Aug 4, 2016 at 7:27 PM, Chris Adams  wrote:

> Once upon a time, James Michels  said:
> > Correct me if I'm wrong but I think Dan meant target's IPs. So if you
> have
> > a SAN backend with two IP addresses, you first discover LUNs from first
> IP
> > address, then discover LUNs from the second IP address, and so on... once
> > you have them all, you just check them and click on "OK" so the same
> target
> > is added with several IP addresses. You don't need to have one IP address
> > per oVirt server.
>
> Well, to do iSCSI multipath right, you should also have multiple
> interfaces on each client server, each with its own IP.  I'm not sure
> how you do that with oVirt.
>

We support it as well - it's poorly called 'iSCSI bonding'.

BTW, having two IPs on a single subnet is not a great idea - it usually
mean you have a SPOF somewhere (the switch perhaps?).
Y.



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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread James Michels
I guess you mean the 'iSCSI multipath' sub-tab under the 'Datacenters' tab.
There you can assign one or more networks to a iSCSI backend. In my opinion
you cannot have more than one interface within the same network segment to
do multipath, as you would have connectivity issues (not sure if ovirt
restricts creating two overlapping networks)

2016-08-04 17:27 GMT+01:00 Chris Adams :

> Once upon a time, James Michels  said:
> > Correct me if I'm wrong but I think Dan meant target's IPs. So if you
> have
> > a SAN backend with two IP addresses, you first discover LUNs from first
> IP
> > address, then discover LUNs from the second IP address, and so on... once
> > you have them all, you just check them and click on "OK" so the same
> target
> > is added with several IP addresses. You don't need to have one IP address
> > per oVirt server.
>
> Well, to do iSCSI multipath right, you should also have multiple
> interfaces on each client server, each with its own IP.  I'm not sure
> how you do that with oVirt.
>
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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Chris Adams
Once upon a time, James Michels  said:
> Correct me if I'm wrong but I think Dan meant target's IPs. So if you have
> a SAN backend with two IP addresses, you first discover LUNs from first IP
> address, then discover LUNs from the second IP address, and so on... once
> you have them all, you just check them and click on "OK" so the same target
> is added with several IP addresses. You don't need to have one IP address
> per oVirt server.

Well, to do iSCSI multipath right, you should also have multiple
interfaces on each client server, each with its own IP.  I'm not sure
how you do that with oVirt.

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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread James Michels
Hello Chris,

Correct me if I'm wrong but I think Dan meant target's IPs. So if you have
a SAN backend with two IP addresses, you first discover LUNs from first IP
address, then discover LUNs from the second IP address, and so on... once
you have them all, you just check them and click on "OK" so the same target
is added with several IP addresses. You don't need to have one IP address
per oVirt server.


2016-08-04 16:32 GMT+01:00 Chris Adams :

> Once upon a time, Dan Yasny  said:
> > Normally you
> > 1. enter the IP
> > 2. click discover
> > 3. login to whatever was found
> > 4. enter another IP instead of the first
> > 5. goto 2
>
> How do you give the oVirt server two IPs (in the same subnet) though?
>
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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Chris Adams
Once upon a time, Dan Yasny  said:
> Normally you
> 1. enter the IP
> 2. click discover
> 3. login to whatever was found
> 4. enter another IP instead of the first
> 5. goto 2

How do you give the oVirt server two IPs (in the same subnet) though?

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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Dan Yasny
On Thu, Aug 4, 2016 at 10:24 AM, Tadas <ta...@ring.lt> wrote:

> Multipath is more a SAN thing, - not a tcp/ip.
>

Not when it comes to iSCSI


> You should use something like LACP group on two (or more) of your network
> interfaces.
>

Absolutely not. It is always better to let multipath deal with paths
leading to block storage LUNs, and the underlying fabric does not matter.


> Also you will have to configure your switch accordingly. You will not have
> to worry about second ip. LACP bonded interface will use one IP, but will
> fail-over to one of nics if needed.
>


Again, do NOT use bonds for iscsi traffic. Let multipath deal with it.


> *From:* James Michels <karma.sometimes.hu...@gmail.com>
> *Sent:* Thursday, August 4, 2016 5:13 PM
> *To:* users <users@ovirt.org>
> *Subject:* [ovirt-users] Multipath iSCSI with several IPs
>
> Hello,
>
> I want to add an iSCSI based storage domain. For that I add a domain on
> the Storage tab with one of the IPs (say 10.10.10.1), but for failover
> purposes I'd like to use multipath to add a failover IP so if the first one
> fails, LUNs can be reached via the second (say 10.10.10.2).
>
> How can this be done in oVirt 4.0.1? I have not seen a way how to add the
> second IP for multipath purposes.
>
> Thank you
>
> James
>
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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Tadas
Multipath is more a SAN thing, - not a tcp/ip.
You should use something like LACP group on two (or more) of your network 
interfaces. Also you will have to configure your switch accordingly. You will 
not have to worry about second ip. LACP bonded interface will use one IP, but 
will fail-over to one of nics if needed.
From: James Michels 
Sent: Thursday, August 4, 2016 5:13 PM
To: users 
Subject: [ovirt-users] Multipath iSCSI with several IPs

Hello, 

I want to add an iSCSI based storage domain. For that I add a domain on the 
Storage tab with one of the IPs (say 10.10.10.1), but for failover purposes I'd 
like to use multipath to add a failover IP so if the first one fails, LUNs can 
be reached via the second (say 10.10.10.2).

How can this be done in oVirt 4.0.1? I have not seen a way how to add the 
second IP for multipath purposes.

Thank you

James



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Re: [ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread Dan Yasny
Normally you
1. enter the IP
2. click discover
3. login to whatever was found
4. enter another IP instead of the first
5. goto 2

On Thu, Aug 4, 2016 at 10:13 AM, James Michels <
karma.sometimes.hu...@gmail.com> wrote:

> Hello,
>
> I want to add an iSCSI based storage domain. For that I add a domain on
> the Storage tab with one of the IPs (say 10.10.10.1), but for failover
> purposes I'd like to use multipath to add a failover IP so if the first one
> fails, LUNs can be reached via the second (say 10.10.10.2).
>
> How can this be done in oVirt 4.0.1? I have not seen a way how to add the
> second IP for multipath purposes.
>
> Thank you
>
> James
>
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[ovirt-users] Multipath iSCSI with several IPs

2016-08-04 Thread James Michels
Hello,

I want to add an iSCSI based storage domain. For that I add a domain on the
Storage tab with one of the IPs (say 10.10.10.1), but for failover purposes
I'd like to use multipath to add a failover IP so if the first one fails,
LUNs can be reached via the second (say 10.10.10.2).

How can this be done in oVirt 4.0.1? I have not seen a way how to add the
second IP for multipath purposes.

Thank you

James
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