SATA vs SCSI ...

[Sergey N. Voronkov]

On Sun, Jun 26, 2005 at 11:34:22PM -0300, Marc G. Fournier wrote:
> 
> looking at the specs between two cards, the SATA card(s) seem to rate 
> ~100-150MB/s on each channel (if I'm reading right), with both the 3Ware 
> and ICP cards having 4 individual channels ... looking at the SCSI cards, 
> they are rated at 320MB/s, but that is total for the SCSI bus itself, 
> right?

It is dependant of the card too. You can get a 3 channel Ultra320 card for 3
drive RAID 5...

> So, if I have three drives on  a SCSI bus, each 'maxing out evenly', I'd 
> be cap'd at about the same 100MB/s per drive, no?
>
> In fact, looking at the SATA 2.x specs, each chanell there is rated at 
> 300MB/s, which, again, if I could 'max out evenly', could seriously blow 
> away the SCSI bus itself ...

That is a theory...
 
> *If* I'm reading this right ... ?

And now from my practice:

1) You CAN'T get maximal throuput from 150/160 MB/s bus - the is no such
drives today at the market.

2) Avg. seek and access time of 7200 SATA drives are FAR BELOW such of old
Seagate Cheetah/Maxtor Athlas 10K. So is a situation with a WD Raptor 10K
SATA too - they are SLOWER! (I'm not shure why, but from my test:

2xPIII-1.4/1G RAM/2x36G Cheeta 10K in RAID 1 (AMR Express; One U160 channel)
ws.
2xXeon 3.0/2G RAM/2x72G Raptor in RAID 1 (Intel SRCS16; Separate SATA-150 
channel for each drive)

Ports three checkout is about 20% faster on the first comp.

As an result: If you need to have FAST disk subsystem - buy SCSI. If you need
large storage or you don't want to pay to much money - buy SATA.

Best Ragards,

Serg N. Voronkov,
Sibitex JSC.