[dm-devel] Native systemd service files for multipathd

[Kay Sievers]

On Tue, Aug 23, 2011 at 17:06, Hannes Reinecke <hare at suse.de> wrote:
> On 08/22/2011 06:35 PM, Kay Sievers wrote:
>>
>> On Mon, Aug 22, 2011 at 17:45, Hannes Reinecke<hare at suse.de>  wrote:
>>>
>>> On 08/22/2011 03:47 PM, Christophe Varoqui wrote:
>>>>
>>>> On jeu., 2011-06-30 at 14:10 +0000, "Jóhann B. Guðmundsson" wrote:
>>>>>
>>>>> Is anyone taking a look at porting the multipathd legacy sysv init
>>>>> script to native systemd unit file?
>>>>>
>>>>> I filed 690828 on 2011-03-25 and yet to receive somekind of response on
>>>>> it and unless some action is taken then a) device-mapper-multipath will
>>>>> be blocking the Fedora 16 alpha release or b) be ripped out of @base
>>>>> and
>>>>> be made sure it does not get installed on the official livecd.
>>>>>
>>>> What is the status of this request ? Has anyone stepped-in to the job ?
>>>> If not I'll look into it. If you have Fedora-specific systemd
>>>> implementation guideline, please point me to the appropriate
>>>> documentation.
>>>>
>>> I have talked with Kay&  Lennart about this.
>>>
>>> The main problem here is that we don't / can't know if a device is
>>> multipathed or not; this is basically a policy decision.
>>> Even a simple switch (multipath on/off) wouldn't suffice here, as this
>>> particular device might be excluded via the configuration file.
>>>
>>> Idea here is to modify the 'multipath' program to determine if a
>>> particular
>>> device is handled by multipath or not. If so, _no other_ configuration
>>> must
>>> be done in that device.
>>> The multipathd daemon itself already listens on events from the udev
>>> socket;
>>> it should be pretty trivial to convert that to socket activation.
>>>
>>> And, of course, we need to solve the mount problem. Last I've heard was
>>> that
>>> systemd _won't_ be handling mounting, which in effect means we cannot
>>> mount
>>> any systems provided via multipath ...
>>>
>>> What is the status here?
>>
>> It fully support mounts on boot, dynamically created, or on hotplug,
>> with or without automounter support.
>>
>> But it will not assemble/handle/know anything about any dm/md devices.
>>
> Yeah, but this should taken care of if and when LVM2 and MD gets converted
> to systemd, right ?

Right. The tool to do that would probably be some raid-assembly daemon
that replaces the insanity in current shell scripts and called tools
that scan /dev. There is no plan currently to integrate any
raid-assembly into systemd natively.

Kay