[ovirt-users] iSCSI VLAN host connections - bond or multipath & IPv6

[Ben Bradley]

On 28/09/17 22:27, Ben Bradley wrote:
> On 28/09/17 08:32, Yaniv Kaul wrote:
>>
>>
>> On Wed, Sep 27, 2017 at 10:59 PM, Ben Bradley <listsbb at virtx.net 
>> <mailto:listsbb at virtx.net>> wrote:
>>
>>     Hi All
>>
>>     I'm looking to add a new host to my oVirt lab installation.
>>     I'm going to share out some LVs from a separate box over iSCSI and
>>     will hook the new host up to that.
>>     I have 2 NICs on the storage host and 2 NICs on the new Ovirt host
>>     to dedicate to the iSCSI traffic.
>>     I also have 2 separate switches so I'm looking for redundancy here.
>>     Both iSCSI host and oVirt host plugged into both switches.
>>
>>     If this was non-iSCSI traffic and without oVirt I would create
>>     bonded interfaces in active-backup mode and layer the VLANs on top
>>     of that.
>>
>>     But for iSCSI traffic without oVirt involved I wouldn't bother with
>>     a bond and just use multipath.
>>
>>      From scanning the oVirt docs it looks like there is an option to
>>     have oVirt configure iSCSI multipathing.
>>
>>
>> Look for iSCSI bonding - that's the feature you are looking for.
> 
> Thanks for the replies.
> 
> By iSCSI bonding, do you mean the oVirt feature "iSCSI multipathing" as 
> mentioned here 
> https://www.ovirt.org/documentation/admin-guide/chap-Storage/ ?
> 
> Separate links seems to be the consensus then. Since these are links 
> dedicated to iSCSI traffic, not shared. the ovirtmgmt bridge lives on 
> top of an active-backup bond on other NICs.
> 
> Thanks, Ben

And an extra question about oVirt's iSCSI multipathing - should each 
path be a separate VLAN+subnet?
I assume it should be separate VLANs for running separate physical 
fabrics if desired.

Thanks, Ben

> 
>>     So what's the best/most-supported option for oVirt?
>>     Manually create active-backup bonds so oVirt just sees a single
>>     storage link between host and storage?
>>     Or leave them as separate interfaces on each side and use oVirt's
>>     multipath/bonding?
>>
>>     Also I quite like the idea of using IPv6 for the iSCSI VLAN, purely
>>     down to the fact I could use link-local addressing and not have to
>>     worry about setting up static IPv4 addresses or DHCP. Is IPv6 iSCSI
>>     supported by oVirt?
>>
>>
>> No, we do not. There has been some work in the area[1], but I'm not 
>> sure it is complete.
>> Y.
>>
>> [1] 
>> https://gerrit.ovirt.org/#/q/status:merged+project:vdsm+branch:master+topic:ipv6-iscsi-target-support 
>>
>>
>>
>>     Thanks, Ben
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> 
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