Re: [9fans] "FAWN: Fast array of wimpy nodes" (was: Plan 9 - the next 20 years)

[erik quanstrom <quanstro@quanstro.net>]

> I think the key to successfully being able to use Plan 9 commercially
> is to use its unique technical advantages to exploit disruptive
> economic changes.

works for coraid.

> Economics beats technology every time (e.g., x86/amd64 vs.
> MIPS/Itanium, Ethernet vs. Infiniband, SATA vs. SCSI) so
> don't try to fight it.

if those examples prove your point, i'm not sure i agree.

having just completed a combined-mode sata/sas driver,
scsi vs ata is is fresh on my mind.  i'll use it as an example.

sata and scsi can't be directly compared because sata is an
specific physical/data layer that supports the ata 7+ command set*,
while scsi is a set of command sets and an a set of physical
standards.

if you mean that the ata command set is not as good as the
scsi command set, i don't think i agree with this.  the ata
command set is simpler, and still gets the job done.  both
suffer from bad command formatting, but scsi is worse.  ata
has 28 bit and 48 bit (sic) commands.  scsi has 6, 10, 12, 16
and 32-byte commands).  one can find problems with both
command sets.

if you mean that sata is worse than sas, i think that's a hard
sell, too.  sata and sas use the same physical connections at
the same speeds.  there are some data-layer differences, but
they seem to me to be differences without distinction.  (as
evidenced by the aforementioned combined-mode hba.)

the main difference between sas and sata is that sas supports
dual-porting of drives so that if your hba fails, your drive can
keep working.  i don't see that as a real killer feature.  hard
drives fail so much more often than hbas.

- erik