SCSI AND FIBRE speed

[SAM_24]

Hi,

I want to know what is speed of data flow between server and storage array using scsi and fibre channel adapters.

Is this right?

SCSI3 - 40M MByts/sec
Fibre - 100 MBytes/sec.

Thanks.

[Vincent Farrugia]

Hello,

Nope, that's for fast Wide SCSI!

SCSI3 bus is 160MBytes/sec. SCSI2 is 80MBytes/sec.

Fibre is 1063Mbit/sec. Notice the bit. That would be 133MBytes/sec.

Advantages of Fibre here is the length of cable, number of devices per loop, and lower error rates, amongst others.

HTH,
Vince

[Leif Halvarsson_2]

Hi
Some other notes about fibre channel.
There is also a 2GB FC standard ( many products avilable).
And FC is full duplex 1 or 2GB in both directions. Important for example in backup solutions.

[Oliver Haensel]

Hello Raj,

please have a look at the following websites:
www.t10.org SCSI standard documents
www.t11.org FC standard documents

SCSI technology is evolving that way...
FastWide SCSI 20MB/s
Ultra SCSI 40MB/s
Ultra2 SCSI 80MB/s
Ultra3 SCSI 160MB/s
Ultra320 SCSI 320MB/s (on the market)
Ultra640 SCSI 640MB/s

SCSI-2 defines the FastWide Differential SCSI with 20MB/s and HighVoltageDifferential Interface while SCSI-3 introduces the LowVoltageDifferential Interface which allows higher speeds and lower-cost cabling.

an Fiber Channel?
1GBit/s 100MB/s
2GBit/s 200MB/s (on the market)
10GBit/s 1GB/s

Please note that these are raw numbers which indicate the bandwith of the transport pipe between host and storage. The real numbers of transferred data are smaller..
i.e. Ultra3 up to 120MB/s SCSI
i.e. 1GBit/s FC up to 80MB/s SCSI data (raw data could be up to 95MB/s)
The real I/O speed also depends on the ability of the storage to provide the data requested and the server to process it...

Fiber Channel gives you more flexibility with the number of devices and distance between it. It enables you to share your storage resources between hosts in a networked architecture. In terms of speed both technologies can provide you what you need.

Hope that helps

-Oliver-