Thanks. If I am reading this correctly the ability to remove an iSCSI gateway would allow the remaining iSCSI gateways to take over for the removed gateway's LUN's as of > 3.0. Thats good, we run 3.2. However, because the actual update of the central config object happens from the to-be-deleted iSCSI gateway, despite where the gwcli command is issued, it will fail to actually remove said gateway from the object if that gateway is not functioning. 

I guess this leaves the question still of how to proceed when one of the iSCSI gateways fails permanently?  Is that possible, or is it potentially possible other than manually intervening on the config object? If its not possible would the best course of action be to have standby hardware and quickly recreate the node or perhaps run the gateways more ephemerally, from a VM or container? 

Thanks again.

Respectfully,

Wes Dillingham


On Tue, Dec 3, 2019 at 2:45 PM Mike Christie <mchristi@redhat.com> wrote:
I do not think it's going to do what you want when the node you want to
delete is down.

It looks like we only temporarily stop the gw from being exported. It
does not update the gateway.cfg, because we do the config removal call
on the node we want to delete.

So gwcli would report success and the ls command will show it as no
longer running/exported, but if you restart the rbd-target-api service
then it will show up again.

There is an internal command to do what you want. I will post a PR for
gwlci and so it can be used by dashboard.


On 12/03/2019 01:19 PM, Jason Dillaman wrote:
> If I recall correctly, the recent ceph-iscsi release supports the
> removal of a gateway via the "gwcli". I think the Ceph dashboard can
> do that as well.
>
> On Tue, Dec 3, 2019 at 1:59 PM Wesley Dillingham <wes@wesdillingham.com> wrote:
>>
>> We utilize 4 iSCSI gateways in a cluster and have noticed the following during patching cycles when we sequentially reboot single iSCSI-gateways:
>>
>> "gwcli" often hangs on the still-up iSCSI GWs but sometimes still functions and gives the message:
>>
>> "1 gateway is inaccessible - updates will be disabled"
>>
>> This got me thinking about what the course of action would be should an iSCSI gateway fail permanently or semi-permanently, say a hardware issue. What would be the best course of action to instruct the remaining iSCSI gateways that one of them is no longer available and that they should allow updates again and take ownership of the now-defunct-node's LUNS?
>>
>> I'm guessing pulling down the RADOS config object and rewriting it and re-put'ing it followed by a rbd-target-api restart might do the trick but am hoping there is a more "in-band" and less potentially devastating way to do this.
>>
>> Thanks for any insights.
>>
>> Respectfully,
>>
>> Wes Dillingham
>> wes@wesdillingham.com
>> LinkedIn
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>