RE: iSCSI: More on naming and discovery

[Black_David@emc.com]

With my WG co-chair hat off:

> You said "...requiring a DNS resolution to find the storage required to
get
> the server up to the first point at which it can be worked on (e.g.,
single
> user mode in Unix) is an invitation to trouble".
> 
> I am not sure that I believe that as much as you, however, there is
> probably a reasonable compromise.

I think so, especially as in 20/20 hindsight, "an invitation to trouble"
might have been better stated as "a potential invitation to trouble."

The discussion of alternatives seems to boil down to two important points:
- Some network administrators may consciously choose to make
	this level of booting dependent on DNS because their DNS
	services are highly reliable.  If they really know what they're
	doing, that's probably ok.
- There are a number of ways to pre-evaluate a DNS resolution so
	that an IP address is available at boot time, including having
	a management tool do it, and storing the results of the last
	resolution in non-volatile memory.
I agree that these are viable alternatives.

Text along the following lines would be acceptable to me:

  During the system boot process, location of and access to iSCSI
  storage required to boot the system SHOULD NOT depend on resolution
  of DNS host names to IP addresses unless the consequences of
  the resulting dependence of the boot process on DNS are
  well understood and acceptable.

Discussion of the examples of how to pre-evaluate a DNS resolution
could then follow, and it might be worth noting that if non-volatile
memory (e.g., EEPROM) is used as a backstop to DSN resolution,
then changes to the IP address of the accessed storage entail
changes to that non-volatile memory in order to avoid future problems.

Thanks,
--David

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David L. Black, Senior Technologist
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