[Stgt-devel] [PATCH] tgt-admin: support persistent device binding

[Tomasz Chmielewski]

FUJITA Tomonori schrieb:
> On Tue, 29 Jul 2008 13:51:55 +0300
> Doron Shoham <dorons at Voltaire.COM> wrote:
> 
>> Eli Dorfman wrote:
>>>>> maybe use the following format :
>>>>> <target xyz>
>>>>>     <backing-store /dev/sdb>
>>>>>           properties  custom # use properties specified below or
>>>>> default (generate the deadbeaf id) or direct (get real serial number)
>>>>>           serial-number 12345678
>>>>>           vendor myvendor
>>>>>     </backing-store>
>>>>> </target>
>>>>>
>>>>> what do you think?
>>>> Hmm, 'properties custom' looks unnecessary for me. If a device file of
>>>> a disk drive is used as backing-store and none of the properties are
>>>> specified, we can use the physical properties.
>>> we need something like properties to differentiate between disk (read
>>> real props), file (generate unique serial number
>>> disk-sn-partition-filename) and custom (applicable to any case).
>>> we can call this attribute: "type" which can accept 3 values disk,
>>> file or custom (default).
>> This is what I suggest:
>>
>> <target iqn.2007-04.com.example:san.monitoring>
>>    <backing-store /tmp/ramdisk/lun1>
>>       type default
>>       serial 12345678
>>       vendor my_vendor
>>       product_id my_id
>>       product_rev my_rev
>>    </backing-store>
>>
>>    <backing-store /dev/sdc>
>>       type disk
>>    </backing-store>
>> </target>
>>
>> The reason we use XML is that the original implementation used XML.
>>
>> We suggest two types:
>> 1. disk: "real" physical devices, where we read the properties from the device itself - i.e. storage disks.
>> 2. default - use default tgt values. 
>>    We can also override the properties with user defined values (optional).
>>
>> The reason for the type attribute is to differentiate between these two types.
> 
> I don't know anything about XML but should it be something like?
> 
> <target iqn.2007-04.com.example:san.monitoring>
>    <lun 0>
>      type sbc
>      backing-store

What we use currently in tgt-admin is a mix of XML and a flat config file, I would say.
With the benefits of both (easy hand editing; it is clear where one target definition starts and where it ends).


If it was "proper XML", it should look like:

<target iqn.2007-04.com.example:san.monitoring>
	<lun 0>
		<type sbc />
		<backing-store />
	</lun>
</target>

Which is not that nice for hand editing anymore - forget one slash in one place (i.e., after "type sbc"), and your whole config file is invalid.


However this one still looks OK and makes sense I would say, if we want to precisely configure different luns?

 <target iqn.2007-04.com.example:san.monitoring>
    <lun 0>
      type sbc
      backing-store


-- 
Tomasz Chmielewski 
http://wpkg.org