[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-23 Thread Uwe Laverenz

Am 22.07.20 um 21:55 schrieb Mark R:


Thanks, Uwe. Am I understanding correctly that you're just letting
your nodes attach to the iSCSI storage on their own by leaving
"node.startup = automatic" in /etc/iscsi/iscsid.conf so the hosts
attach to all known targets as they boot, long before oVirt services
ever attempt to connect them? I've considered flipping that to


No, I use OVirt to connect to the iSCSI targets, this works as expected. 
The thing I do not use are OVirt's iSCSI bonds.


What I configure manually is multipathd in order to use round robin policy.


As another poster below mentioned, going the route of two separate
iSCSI bonds in the "iSCSI Multipath" section does work when you're
adding new storage domains. The aspect he talks about, where you
connect both paths and save it, isn't possible if you import an
existing storage domain. When importing, the UI won't expose the
"Add" button that's available when creating a new domain, so you
can't add redundant paths. You can import the storage, then edit it
and discover/login to the other path, but that does _not_ save to the
database and will not persist across reboots or connect on other
hosts you add to the cluster (have to login manually on each). You
can't edit your iSCSI bonds and check the box for these manually
logged in targets either, they'll never populate in that part of the
UI so can't be selected. I think it's just a UI issue because some
very easy fidling in the database makes it work exactly as you'd
expect (and as it does for domains you newly add instead of
importing ).


This sounds quite ugly, I wasn't aware of this.


Sorry, rambling, but I am curious about your "node.startup" setting
in iscid.conf.  If left at 'automatic' (the default), are your hosts
attaching all the disks as they boot and oVirt doesn't mind that? It
could be the path I'll take as honestly I'd much prefer configuring
the storage connections directly.


As I said, the only thing I change is /etc/multipath.conf:

https://lists.ovirt.org/pipermail/users/2017-July/083308.html

cu,
Uwe
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[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-22 Thread Mark R

> I don't use them as multipathing generally works without OVirt bonds in 
> my setup, I configured multipathd directly to use round robin e.g.

Thanks, Uwe. Am I understanding correctly that you're just letting your nodes 
attach to the iSCSI storage on their own by leaving "node.startup = automatic" 
in /etc/iscsi/iscsid.conf so the hosts attach to all known targets as they 
boot, long before oVirt services ever attempt to connect them? I've considered 
flipping that to automatic, it's currently on "manual" as the idea was "let's 
let oVirt connect and manage the storage it wants".

As another poster below mentioned, going the route of two separate iSCSI bonds 
in the "iSCSI Multipath" section does work when you're adding new storage 
domains. The aspect he talks about, where you connect both paths and save it, 
isn't possible if you import an existing storage domain. When importing, the UI 
won't expose the "Add" button that's available when creating a new domain, so 
you can't add redundant paths. You can import the storage, then edit it and 
discover/login to the other path, but that does _not_ save to the database and 
will not persist across reboots or connect on other hosts you add to the 
cluster (have to login manually on each). You can't edit your iSCSI bonds and 
check the box for these manually logged in targets either, they'll never 
populate in that part of the UI so can't be selected. I think it's just a UI 
issue because some very easy fidling in the database makes it work exactly as 
you'd expect (and as it does for domains you newly add instead of importing
 ).

Sorry, rambling, but I am curious about your "node.startup" setting in 
iscid.conf.  If left at 'automatic' (the default), are your hosts attaching all 
the disks as they boot and oVirt doesn't mind that? It could be the path I'll 
take as honestly I'd much prefer configuring the storage connections directly.

Thanks!
Mark
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[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-20 Thread Erez Zarum
I think there's a misunderstanding behind the name, what happens is the 
following:
When you deploy the hosted-engine you can choose only one target and path 
probably, so it uses the "default" interface, this is also true when you run a 
scan/discovery.
As example, if using a standard iSCSI configuration (best practice is also 
having a different network switches, etc.. which i show in this example, but it 
works well even if you don't have), you will probably have two interfaces, each 
in his own Fault Domain, so let's say we have eth3 as FD1 and eth4 as FD2.
Subnets:
 FD1 = 192.168.100.0/24
 FD2 = 192.168.200.0/24
You will then create a logical network for each of those Fault Domains, so FD1 
and FD2, make sure those are only attached and are not marked as VM network and 
are not "Required".
After that, you will have to attach those logical networks to the hosts and 
configure their IP.
For example on host1:
 We attach FD1 to eth3 and give it 192.168.100.11/24
 We attach FD2 to eth4 and give it 192.168.200.11/24
Note that i did not specify any gateway, It's a simple Layer2 configuration.
You will have to do this for each host (you can use ansible for automation 
which makes it very simple).
After you have attached you first Storage Domain using iSCSI and did the 
procedure above you will under the Datacenter a new Tab named "iSCSI 
Multipathing" the name is confusing because it does not control the Multipath, 
configuration of the Multipath should be done by referencing to the vendor best 
practice and configure it under "/etc/multipath/conf.d" because the VDSM 
override /etc/multipath.conf
In the "iSCSI Multipathing" section you will need to add those two Fault 
Domains.
So for FD1 you will need to select the logical network we created earlier named 
"FD1" and then select the appropriate targets related to it only!, do the same 
for FD2.
What happens behind the scene is that VDSM configure iSCSI (oVirt/RHEL uses 
libiscsi).
You can observe that two interfaces were created, eth3 and eth4: "iscsiadm -m 
iface"
Then look at the sessions: "iscsiadm -m session"
Easiest way around is just seeing what was created in the "/var/lib/iscsi" 
folder: "find /var/lib/iscsi"
You will see how VDSM configured iSCSI to interact with the targets, it tells 
it to use those specific interfaces to those specific targets.
you can observe a session "iscsiadm -m session -r1 -P3" to get more details.
So what really happened now is that VDSM will take care of making sure iSCSI 
works on each host, it will automatically login to the targets using those 
interfaces.

I do agree the name "Multipathing" is confusing. 

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[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-20 Thread Patrick Lomakin
I don't quite understand what multipath is, but when I deployed it in my iSCSI 
repository, only one ip address is specified when installing hosted-engine. 
However, in order to specify the second subnet, I went to my host portal where 
I was deploying the engine and added the second subnet in the Storage -> iSCSi 
targets section. It should be noted that the storage is connected to hosts 
directly. However, after that when adding subsequent hosts through the engine I 
saw through their administration panels that in Storage -> iScsi section there 
are also two targets with different subnets and the command on the host 
multipath -ll also showed the normal operation of the two targets. I hope this 
helps you in any way.  
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[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-18 Thread Vinícius Ferrão via Users
I second that, I’ve tirelessly talked about this and just given up, it’s a 
basic feature that keeps oVirt lagging behind.

> On 18 Jul 2020, at 04:47, Uwe Laverenz  wrote:
> 
> Hi Mark,
> 
> Am 14.07.20 um 02:14 schrieb Mark R:
> 
>> I'm looking through quite a few bug reports and mailing list threads,
>> but want to make sure I'm not missing some recent development.  It
>> appears that doing iSCSI with two separate, non-routed subnets is
>> still not possible with 4.4.x. I have the dead-standard iSCSI setup
>> with two separate switches, separate interfaces on hosts and storage,
>> and separate subnets that have no gateway and are completely
>> unreachable except from directly attached interfaces.
> 
> I haven't tested 4.4 yet but AFAIK nothing has changed, OVirt iSCSI bonds 
> don't work with separated, isolated subnets:
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1474904
> 
> I don't use them as multipathing generally works without OVirt bonds in my 
> setup, I configured multipathd directly to use round robin e.g..
> 
> cu,
> Uwe
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[ovirt-users] Re: iSCSI multipath with separate subnets... still not possible in 4.4.x?

2020-07-18 Thread Uwe Laverenz

Hi Mark,

Am 14.07.20 um 02:14 schrieb Mark R:


I'm looking through quite a few bug reports and mailing list threads,
but want to make sure I'm not missing some recent development.  It
appears that doing iSCSI with two separate, non-routed subnets is
still not possible with 4.4.x. I have the dead-standard iSCSI setup
with two separate switches, separate interfaces on hosts and storage,
and separate subnets that have no gateway and are completely
unreachable except from directly attached interfaces.


I haven't tested 4.4 yet but AFAIK nothing has changed, OVirt iSCSI 
bonds don't work with separated, isolated subnets:


https://bugzilla.redhat.com/show_bug.cgi?id=1474904

I don't use them as multipathing generally works without OVirt bonds in 
my setup, I configured multipathd directly to use round robin e.g..


cu,
Uwe
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