On Wed, May 9, 2018 at 10:37 AM, Gianluca Cecchi <gianluca.cecchi(a)gmail.com>
wrote:
On Wed, May 9, 2018 at 10:23 AM, Veiko Kukk <veiko(a)linux.ee>
wrote:
> 2018-05-09 11:07 GMT+03:00 Gianluca Cecchi <gianluca.cecchi(a)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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