Configuring Dual or more SCSI cards in a System

[Matthew Murdock]

Is it still necessary to have unique Scsi Ids for all Scsi host adapters in a System, whether P.c. or HP/ux Servers.

[Sachin Patel]

YES.
unless if you are using SAN then more then one system can see more then one tape/disk on same SCSI id.

i.e if you have tape id 6 then two system can see same tape drive.

Sachin

[Matthew Murdock]

So, then in a one system setup, each scsi controller has to have unique id's assigned to each scsi controller? I thought they did, but, I have forgotten why.
For example, in a X86 PCI based system, each pci bus has its own memory address. Why would the scsi host adapter need to have a unique id's?

[Sandip Ghosh]

By default SCSI Card is set for SCSI ID 7. Actually in a single SCSI chain all the ID's should be unique. Because SCSI devices are accessed by their ID and there address also defined by their SCSI ID. If you put multiple SCSI Adapter in a host all of them can be set as ID 7 but What ever the device connected through that adapter can't have ID 7.

Hope it helps

Sandip

[pap]

Hi It is immaterial thing to have common addresses for devices on different SCSI controllers.

1.The devices on the same SCSI controller card MUST nOT have same SCSI ID.

2. SCSI controller card has SCSI ID fix and it is 7.

3.for a particular machine, the SCSI adapters have different Instance number and hence the device address will be unique in all sense and hence there is no chance to have two same device address for different SCSI cards as well as devices among all SCSI cards.

4. Even if you are connected to SAN devices are allocated to different systems separately and hence the device address will be different for all the devices in Storage box.

-pap

[A. Clay Stephenson]

Hi:

The only requirement that each device on a single SCSI bus have a unique SCSI target ID. If you have 4 SCSI controllers on a single host then all can be set to the same id (usually 7 - the highest priority ID).

Occasionally, two hosts share a common SCSI bus
like this:
Host A SCSI Controller (ID 7) ----- Disk (ID 5) --- Tape (ID 2) --- Host B SCSI Controller (ID 6 - next highest priority).

[Marino Meloni_1]

hi

--1 on one scsi host adapter, each device need to have unique id

--2 if you have two or more host adapter on one pc, rules 1 aply for each host adapter,

--3 if there is no bus sharing between hosts, each host is not dependent of each other


bye


marino