On Wed, May 9, 2018 at 10:37 AM, Gianluca Cecchi <gianluca.cecchi@gmail.com> wrote:
On Wed, May 9, 2018 at 10:23 AM, Veiko Kukk <veiko@linux.ee> wrote:
2018-05-09 11:07 GMT+03:00 Gianluca Cecchi <gianluca.cecchi@gmail.com>:
"
IMPORTANT
If you are using iSCSI storage, do not use the same iSCSI target for the shared
storage domain and data storage domain.
"

Does it simply remark that the LUN for the hosted engine storage (shared storage domain) should be different from the LUN(s) used then for normal VMs (data storage domain), or what?

I think it doesn't refer to the portal that for some reason needs to be different, correct?

Any clarification about this restrictions?



I do not know. But I would guess it might be to avoid errors during mounting/unmounting those two logically separate storage domains if they are on the same physical resource.

Veiko


Actually I don't understand the meaning of the limitation itself... what target stands for in this context?

That limitation was due to this one:
https://bugzilla.redhat.com/show_bug.cgi?id=1351213
The root issue is clearly explained here: https://bugzilla.redhat.com/show_bug.cgi?id=1351213#c4

The issue was mainly related to the auto import process and now in node-0 deployment flow we are not relying on that anymore (the hosted-engine storage domain is directly created by the engine running on the bootstrap local VM and so it's known by the engine by design) so probably we can just ignore that limitation but honestly I'm not 100% you will not encounter other minor gaps so I'd suggest to still keep two distinct storage domains over two distinct iSCSI targets for production systems.

We are still working to handle the HE storage domain exactly as a regular storage domain but we still have some gaps so it's targeted to 4.3:
https://bugzilla.redhat.com/show_bug.cgi?id=1451653

 
Eg if I configure an iSCSI server using RHEL/CentOS 7.x OS and using targetcli and follow this:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/storage_administration_guide/online-storage-management#osm-target-setup

I have the hierarchy
../target/tpg/luns/[lun0,lun1,lun2]

so it seems I have to create two different targets and put the hosted engine lun under target1/tpg1 and then the data domain luns under target2/tpg2

You can use a single target portal group (by the way now hosted-engine is able to connect all the portals in the same portal group) but I'd recommend to expose two distinct targets so, as an example  with targetcli:

/> iscsi/ create iqn.2018-05.com.example:target1
/> iscsi/ create iqn.2018-05.com.example:target2


Normally if I connect to Enterrise Storage Arrays that offers iSCSI as a connection type (eg EQL or 3PAR) I simply put the portal ip and then I see the mapped LUNs granted to me, so in this case how can I differentiate "target", to be in the "safe/recommended" condition?

Gianluca 


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