[Cluster-devel] fence_scsi - Configuration file

[Jan Friesse <jfriesse@redhat.com>]

Ryan,

Ryan O'Hara wrote:
> On Mon, Aug 03, 2009 at 05:33:51PM +0200, Jan Friesse wrote:
>> Ryan O'Hara napsal(a):
>>> What happens if we list devices and have auto_detect set to 'on'? Will
>>> we ignore the devices? With this auto_detect parameter, it seems that
>>> it will have to be explicitly set to 'off' and devices will have to be
>>> listed if we want to avoid auto-detect. Also, what happens if I set
>>> auto_detect to 'off' and I don't list any devices?
>>>
>> autodetect set to "on" can have one of these two consequences:
>> - Ignore listed device - read only global sections for parameters
> 
> ^^ I think this is the most logical thing to do.

I think first or second are more or less same. It's matter of line with
%device_params_list = ();. Maybe we can make this configurable...

> 
>> - Ignore listed device but use per device parameters in case we will  
>> find this device by old method - This is what is implemented now
>> - Use merge of listed devices and autodetected device
>>
>> autodetect is by default off. When we not have config file, it will  
>> become on. When no devices is listed -> we turn it on
> 
> Shouldn't auto_detect be default on? We want fence_scsi to work like
> it does now unless it is configured otherwise. I was thinking ...
> 
> - If not config file exists, auto_detect is on.
> - If a config file does exists and auto_detect is not defined to be
>   off, auto_detect should default to on ... regardless of whether or
>   not any devices are listed.
> 

- Interesting idea... I'm little fear about BZs like "fence_scsi ignores
my devices listed in config file, ..."

>> I hope nobody will ever set autodetect to off and don't list any device,  
>> but we can do two things:
>> - Ignore this flag and use vgs (this is what code does now)
>> - Do what user want -> no device fencing
> 
> If this evern happens, the node will not register with any
> devices. There are two possible outcomes:
> 
> 1. If a reservation already exists (being held by another node/key),
> the node in question won't have write access to the device(s) since it
> didn't register with anything.
> 2. If a reservation does not already exist, nothing changes and the
> node is completely unprotected and there is no way to fence it.
> 
> I suppose there is a third case where the node is already registered,
> so doing nothing is valid, but this is just pure luck.
> 

I'm really not sure what to do in this case and turning on autodetection
seems to me like a not so bad idea.

Anyway, it looks like we are still standing on one place, so what about
just do this:
- Remove per device options
- Remove all flags and config sections (it looks like they are not needed)
- Let it be as a simple list with [/dev/device\n]* (+ comments)

?

Syntax is ready for future bigger things and parsing code will remain
same -> future additions should be simple. I will just remove (or
ignore) some variables. Thats simple

Regards,
  Honza