• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1359
  • Last Modified:

What is the need of Wide port in a SAS Controller?

In a SAS Controller, as opposed to a narrow port, Wide port has 4 phys per port. All the 4 phys share a common SAS Address. My question is where is this concept of "Wide port" used in real world? and how exactly it achieves the advantages that it claims to provide?
0
raj_ksrt
Asked:
raj_ksrt
1 Solution
 
DavidPresidentCommented:
No, all 4 ports do not share the same common address.  They share the same expander, but every disk has a unique WWN.   You are simply looking at a connector that you can plug a single cable into that "expands" into 4 SAS cables.  
0
 
Handy HolderSaggar makers bottom knockerCommented:
SAS wide ports (either 2, 4 or 8 PHYs combined) aren't used for disk to controller but they are preferable for expander to expander and controller to expander (e.g. hanging an external 25 disk enclosure of a RAID controller's external port) to give bandwidth agrigation.

http://www.scsita.org/aboutscsi/sas/tutorials/SAS_Arch_Overview_public.pdf is a bit out of date but still a good bedtime read.

0
 
Handy HolderSaggar makers bottom knockerCommented:
For example in the wide world, HP Smart Array P800 with a MSA70 uses a 4 PHY wide port that has a single SAS address.
0
Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

 
Handy HolderSaggar makers bottom knockerCommented:
Additional hidden example in the above, the Smart Array P800 has a LSI ROC IC linked to a PMC-Sierra expander IC which also uses a wide port to join the two chips together.

So to get to the disk in the cage the data goes over two wide ports (one between ROC and expander on the P800 and one between expander on P800 and expander on MSA backplane) and then over a single PHY port from the fanout expander on the backplane to the disk.
0
 
Handy HolderSaggar makers bottom knockerCommented:
Dlethe didn't address the subject of a wide port at all, he described a fanout cable which uses 4 narrow ports.
0
 
QlemoC++ DeveloperCommented:
Yes, you are right. Why didn't you object?
0
 
Handy HolderSaggar makers bottom knockerCommented:
Hadn't thought of objecting, recommend 34999210 as answer.
0
 
QlemoC++ DeveloperCommented:
I recommend http:#a34999185 instead - more info.

Qlemo
Cleanup Volunteer
0
 
Handy HolderSaggar makers bottom knockerCommented:
Excellent choice, thanks Qlemo.
0
 
WhackAModCommented:
Restarting closing process
0

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now