Re: What does the letter »r« stand for in /dev/sr0?

[Loïc Grenié]

2009/11/5 Verde Denim <tdldev at gmail.com>:
>
>
> On Wed, Nov 4, 2009 at 10:17 PM, Derek Broughton <derek at pointerstop.ca>
> wrote:
>>
>> Verde Denim wrote:
>>
>> > On Tue, Nov 3, 2009 at 9:34 AM, Derek Broughton
>> > <derek at pointerstop.ca>wrote:
>> >
>> >
>> > Translation - I don't know either... lol
>>
>> Actually, I'd already said that - and suggested "raw" as a wild guess.
>>  But
>> I was intrigued that Detlef thought that knowing what it stood for would
>> prevent errors, since I really can't imagine how most of us would need to
>> know it.
>> --
>> derek
>>
> And knowing the acronym definitions probably won't help the learning too
> much, either.
> But, according to the Linux SCSI sub-system documentation I have, it would
> have to stand for _SCSI_ _READ_ since it is a cd drive that is designated
> read-only. For generic operations on the same device, it would map to sg0
> (_SCSI_ _GENERIC_) in order to gain the write perm. Apparently all of the
> devices like /dev/sr0, /dev/st0, /dev/nst0x map to an sg device for generic
> operations.
> Although _raw_ seems to be a good logical choice.

    I seriously doubt it: a "raw" device in Unix jargon, is a character device.
  /dev/sr0 is a block device and a corresponding raw device would be called
  /dev/rsr0, would be a character device, and it would be impossible to read
  non-multiple of the sector size (2048 bytes for CDs, 512 for most hdd). I
  don't remember if "raw" devices go through page cache or not (probably
  not). So I strongly doubt it is a raw device.

      Loïc