Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alexis HAUSER

>Normally you should not have to do that. It could be that it was not 
>allowed access, and you'd have to leave it a while for the host to retry.

It looped on retrying to make it work for 24 hours...It was authorized. But 
actually when I first add the host, it didn't have authorization. I added 
authorization, then it looped on retrying without success...Until I did what I 
told you.

>At least you have it working now!

Yes thank you, but I'm a bit disappointed by this instability and I'd really 
like to understand what happened...In case it reproduce again. 


>
>
>
>> If you only have one physical interface on each host, there's not much
>> point doing multipath, as you don't stand to gain any performance or
>> resilience.
> I didn't choose if it was multipath or not, someone only gave me access to 
> this storage, but I understand what you mean. However, I'll certainly add 
> bonding later.
>
>
> Do you have any idea what setting maintenance mode and reactivating does on a 
> host ? Does it restart some services ? I don't really understand what just 
> happened actually...
> All I know is that it is used for backup, reinstall and update.

Maintenance mode will migrate any running VMs off that host and enable 
you to do some tasks (including the ones you mention) that you can't do 
when it's running VMs. I believe it stops certain services as well, not 
sure which ones. It's perfectly safe and routine thing to do in RHEV/oVirt.

Thanks, that's certainly what solved the issue then...Or the Dell Bay doing 
weird random stuff who knows ^^ 
I've often heard people telling others setting up a host or engine to 
maintenance mode then reactivate in case of a lot of various issues, it seems 
to be a method to keep in mind.
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alex Crow



On 19/07/16 15:22, Alexis HAUSER wrote:

I'm still finding this hard to understand. If you are using iSCSI, you
/are/ using a server (called the "Target" in SCSI speak). Is the iSCSI
storage actually on the first host?

It's a Dell bay (or "storage array", I think that's the correct name in 
english...)


If it offers iSCSI, it is indeed a "Target". It's effectively a server 
as it's offering up a service on the network! That does explain my 
confusion though...





How did you actually do the
discovery and assign the LUNs? In the storage domain properties you
should be able to see the IP and port of the Targets, something like
"iqn.2012-02:foo-target1,192.168.10.10,3260", and you need to ensure the
second host can reach that IP and port to be able to see the storage.

Actually I jutt made a test : authorize access only to the second host (on the 
Dell bay), it works but only after setting it to maintenance mode and 
reactivate it.
Then authorizing both of the hosts (as initially) make them both working 
now...It doesn't really makes sense...
It is a very strange behavior. Maybe the second host needed to be set in 
maintenance mode then reactivated ?


Normally you should not have to do that. It could be that it was not 
allowed access, and you'd have to leave it a while for the host to retry.


At least you have it working now!






If you only have one physical interface on each host, there's not much
point doing multipath, as you don't stand to gain any performance or
resilience.

I didn't choose if it was multipath or not, someone only gave me access to this 
storage, but I understand what you mean. However, I'll certainly add bonding 
later.


Do you have any idea what setting maintenance mode and reactivating does on a 
host ? Does it restart some services ? I don't really understand what just 
happened actually...
All I know is that it is used for backup, reinstall and update.


Maintenance mode will migrate any running VMs off that host and enable 
you to do some tasks (including the ones you mention) that you can't do 
when it's running VMs. I believe it stops certain services as well, not 
sure which ones. It's perfectly safe and routine thing to do in RHEV/oVirt.


Cheers

Alex


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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alexis HAUSER
>I'm still finding this hard to understand. If you are using iSCSI, you 
>/are/ using a server (called the "Target" in SCSI speak). Is the iSCSI 
>storage actually on the first host?

It's a Dell bay (or "storage array", I think that's the correct name in 
english...)

> How did you actually do the 
>discovery and assign the LUNs? In the storage domain properties you 
>should be able to see the IP and port of the Targets, something like 
>"iqn.2012-02:foo-target1,192.168.10.10,3260", and you need to ensure the 
>second host can reach that IP and port to be able to see the storage.

Actually I jutt made a test : authorize access only to the second host (on the 
Dell bay), it works but only after setting it to maintenance mode and 
reactivate it.
Then authorizing both of the hosts (as initially) make them both working 
now...It doesn't really makes sense...
It is a very strange behavior. Maybe the second host needed to be set in 
maintenance mode then reactivated ? 



>If you only have one physical interface on each host, there's not much 
>point doing multipath, as you don't stand to gain any performance or 
>resilience.

I didn't choose if it was multipath or not, someone only gave me access to this 
storage, but I understand what you mean. However, I'll certainly add bonding 
later.


Do you have any idea what setting maintenance mode and reactivating does on a 
host ? Does it restart some services ? I don't really understand what just 
happened actually...
All I know is that it is used for backup, reinstall and update.
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alex Crow



On 19/07/16 11:13, Alexis HAUSER wrote:

I don't understand. iSCSI is a network storage protocol. What do you
mean by "I access it directly"? When you set up the first host with an
iSCSI storage domain, you would have had to point it to an IP address,
"discover" the LUNs and then attach to them. This sets up the domain.

As I explained, I don't use an iSCSI server, that's what I call accessing it 
"directly".
Yes, my iSCSI storage is working on my first Host, it has been discovered 
successfully, some VM are working on it etc...
The second host can discover it so I don't think it's a network issue.

 From the vdsm logs from second host ("the non working one") it looks like it 
can even see the LVM on it, right ?

Thread-32::DEBUG::2016-07-19 08:41:37,935::lvm::290::Storage.Misc.excCmd::(cmd) FAILED:  = 
'  Volume group "091e0526-1ff3-4ca3-863c-b911cf69277b" not found\n  Cannot process volume 
group 091e0526-1ff3-4ca3-863c-b911cf69277b\n';  = 5



It knows there there are volume groups from the database. You are 
correct, in that it cannot access the VGs/LVs.



On the second host, to access iSCSI storage you will have to have an
interface (defined in "Networks" in oVirt) that can connect to the same
IP and port the first host used.

Yes I have an network interface working on the second host, which is ovirtmgmt. 
I can access all other storage correctly from that host without errors. I can 
discover the iSCSI.

As it is a multipath iSCSI, does it need to acces one different path for each 
host ? I didn't set anything about iSCSI bonding, I use only one single 
interface on each host.


I'm still finding this hard to understand. If you are using iSCSI, you 
/are/ using a server (called the "Target" in SCSI speak). Is the iSCSI 
storage actually on the first host? How did you actually do the 
discovery and assign the LUNs? In the storage domain properties you 
should be able to see the IP and port of the Targets, something like 
"iqn.2012-02:foo-target1,192.168.10.10,3260", and you need to ensure the 
second host can reach that IP and port to be able to see the storage.


Multipath should not make any difference right now, but in order to use 
it effectively you should probably set up an iSCSI bond. The requirement 
for multipath to work properly is that the two physical interfaces on 
the host and initiator are in different IP subnets (and should ideally 
travel via different switches but that is not a hard requirement).


If you only have one physical interface on each host, there's not much 
point doing multipath, as you don't stand to gain any performance or 
resilience.


Cheers

Alex
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alexis HAUSER

> I don't understand. iSCSI is a network storage protocol. What do you 
> mean by "I access it directly"? When you set up the first host with an 
> iSCSI storage domain, you would have had to point it to an IP address, 
> "discover" the LUNs and then attach to them. This sets up the domain.

As I explained, I don't use an iSCSI server, that's what I call accessing it 
"directly".
Yes, my iSCSI storage is working on my first Host, it has been discovered 
successfully, some VM are working on it etc...
The second host can discover it so I don't think it's a network issue.

>From the vdsm logs from second host ("the non working one") it looks like it 
>can even see the LVM on it, right ? 

Thread-32::DEBUG::2016-07-19 08:41:37,935::lvm::290::Storage.Misc.excCmd::(cmd) 
FAILED:  = '  Volume group "091e0526-1ff3-4ca3-863c-b911cf69277b" not 
found\n  Cannot process volume group 091e0526-1ff3-4ca3-863c-b911cf69277b\n'; 
 = 5



> On the second host, to access iSCSI storage you will have to have an 
> interface (defined in "Networks" in oVirt) that can connect to the same 
> IP and port the first host used.

Yes I have an network interface working on the second host, which is ovirtmgmt. 
I can access all other storage correctly from that host without errors. I can 
discover the iSCSI.

As it is a multipath iSCSI, does it need to acces one different path for each 
host ? I didn't set anything about iSCSI bonding, I use only one single 
interface on each host.
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alex Crow



On 19/07/16 10:38, Alexis HAUSER wrote:



Sounds like a possible networking problem. Have you assigned IP
addresses to the storage interfaces on this new host?

hum, What do you mean by storage interfaces ? The other host on the same 
network can access it.


If you're using
VLANs, are they set up correctly on your switch ports for the SAN network?

Yes

I don't use a server to share the iSCSI storage to the hosts, (I access it 
directly). Do I need it ? I saw that in the RHEV doc, on first part of the 
iSCSI section...


I don't understand. iSCSI is a network storage protocol. What do you 
mean by "I access it directly"? When you set up the first host with an 
iSCSI storage domain, you would have had to point it to an IP address, 
"discover" the LUNs and then attach to them. This sets up the domain.


On the second host, to access iSCSI storage you will have to have an 
interface (defined in "Networks" in oVirt) that can connect to the same 
IP and port the first host used.


Alex
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alexis HAUSER


>Sounds like a possible networking problem. Have you assigned IP 
>addresses to the storage interfaces on this new host? 

hum, What do you mean by storage interfaces ? The other host on the same 
network can access it. 

> If you're using 
> VLANs, are they set up correctly on your switch ports for the SAN network?

Yes

I don't use a server to share the iSCSI storage to the hosts, (I access it 
directly). Do I need it ? I saw that in the RHEV doc, on first part of the 
iSCSI section...
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Re: [ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alex Crow



On 19/07/16 09:52, Alexis HAUSER wrote:

Hi,


I just added a second host but it can't become operational, because it can't 
access to the iSCSI storage domain. My first question : is it normal or not, is 
RHEV really able to manage the fact an iSCSI LUN can be accessed from multiple 
hosts ?

Yes, each VM disk is a Logical Volume on that LUN.

Sounds like a possible networking problem. Have you assigned IP 
addresses to the storage interfaces on this new host? If you're using 
VLANs, are they set up correctly on your switch ports for the SAN network?


Alex


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[ovirt-users] Host non operationnal due to an iSCSI problem

2016-07-19 Thread Alexis HAUSER
Hi,


I just added a second host but it can't become operational, because it can't 
access to the iSCSI storage domain. My first question : is it normal or not, is 
RHEV really able to manage the fact an iSCSI LUN can be accessed from multiple 
hosts ?

I don't find anything in the logs, except vdsm logs that seem to give some clue 
: https://bpaste.net/show/e06a11d79040

It seems there are LVM related errors, so does it mean it can access to the 
iSCSI ... ?

By the way it's a multipath iSCSI.

Any ideas ?

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