OCD programmers and backwards compatibility :-).

Les Mikesell lesmikesell at gmail.com
Mon Jan 22 17:30:43 UTC 2007

Peter Gordon wrote:
>> How do you make that happen as the devices are autodetected?  I'd much
>> prefer to have things identified by controller/drive/lun where applicable
>> than to have everything jump around when a new device appears and happens
>> to be detected first.
> This is the great benefit of udev: dynamic device naming. It can track (via
> sysfs querying) the actual make/model/SN of the device, and assign those to
> specific device nodes (using symlink magic). For example, of you have a USB
> memory stick made my FooBar Memory Company, it might register as sda or sdb
> or anything else depending on when you plug it in, but udev can take that
> item information, and automagically maintain an appropriate /dev/memstick
> symlink which points to the appropriate device node.
> Backwards compatibility sometimes means keeping support for things which,
> while not inherently broken, prevent further beneficials workings of the
> software in question.

The scenario I want to handle is being able to take some arbitrary, 
probably used,
scsi disk, plug it into a working system, and know where to find it.  It 
may (in
fact it's pretty likely) that this disk is a dd image clone of another 
drive already
in the system and all of the drives are likely to be the same 
make/model.  I know
from the SCA hot-swap slot or the cable/drive select where all the 
drives are.  I
don't want the system to guess about it or confuse one with the other.  
And I
especially don't want it to move all the other drives around.

>> In other words they didn't care how much of how many people's time they
>> wasted.  Just so they could make names that sounded cute to them.  This
>> sort of user-hostility can only help Windows/OSX's market share.
> They didn't care because in nearly every case, this is taken care of by
> the respective downstream packagers per distribution. If you maintain your
> own software without the aide of any such packaging, then it becomes your
> responsibility to also take care of this new change.

Agreed - programmers should be allowed to make wild and crazy changes, 
but nothing
should be included in a distribution knowing that it will break anything 
working unless you don't care about existing users - or there is no 
other way to do it.

   Les Mikesell
     lesmikesell at gmail.com

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