NVMf initiator persistent across boots

[Max Gurtovoy]

On 3/8/2018 10:39 AM, Johannes Thumshirn wrote:
> On Wed, Mar 07, 2018 at 02:47:52PM +0200, Max Gurtovoy wrote:
>>> [Unit]
>>> Description=NVMf auto discovery service
>>> After=systemd-modules-load.service network-online.target
>>>
>>> [Service]
>>> Type=oneshot
>>> ExecStart=/usr/bin/nvme connect-all
>>> StandardOutput=journal
>>>
>>> [Timer]
>>> OnUnitActiveSec=1min
>>>
>>> [Install]
>>> WantedBy=multi-user.target timers.target
>>> -- 
>>>
>>> That would simply run nvme connect-all once every say minute.
>>> The only problem is that it relies on the kernel to fail
>>> duplicate subsystems. We could enforce that in nvme-cli for that
>>> matter though (we can compare against sysfs address and subsysnqn).
>>
>> Yes, we can also add flag to nvme discover command to add the parameters to
>> the discovery file in case they are not exist.
>>
>>
>>>
>>> Johannes is probably one to know better than me if this is the
>>> correct way to go...
>>
>> Johannes, any comment ?
>>  From what I tried, we need to create a .timer and .service files for
>> systemd...
> 
> Sorry I was on FTO for some days.
> 
> One thing that I feel is missing in this whole "let's just call nvme
> connect-all and we're done" discussion is, we currently can't really
> specifiy how many connections to the target we want to initiate.
> 
> I usually run several nvme connect calls with different --host-traddr
> arguments to connect from multiple HCAs to the target.
> 
> I tried to hack the ability to specify a list of host traddrs for nvme
> connect and connect-all and then just loop the connect cann in
> nvme-cli but this somehow feels wrong.

Why not adding -w <host-traddr> to the /etc/nvme/discovery.conf file lines ?
I guess connect-all will use it too, right ? (need to check it).

> 
> For the systemd service + timer units above, they look good on the
> first sight, but I'm not sure I like the unconditional "polling" of
> the connect-all call.

Yes this is no the perfect solution but I guess future discovery_manager 
should solve it, but we need to find solution till then.

I tought about adding new commands/flags to add/remove parameters to 
/etc/nvme/discovery.conf.
how about adding:
nvme persist-add -t rdma -a 11.11.11.11 -s 4420 -w 11.12.12.12 (will add 
to discovery file "-t rdma -a 11.11.11.11 -s 4420 -w 11.12.12.12")
nvme persist-remove -t rdma -a 11.11.11.11 -s 4420 -w 11.11.12.12 (will 
remove "-t rdma -a 11.11.11.11 -s 4420 -w 11.12.12.12" from discovery file).

Or it's better to add flags to nvme discover ?

> 
> Byte,
> 	Johannes
> 

-Max.