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DS2100 connection

Lacrosse
Regular Advisor

DS2100 connection

If I have 2 connections running from one dual port SCSI controller to the same DS2100 and the SCSI ID's on each interface on the card are the same should I be Okay because the internal path is unique on each connection?? i.e. 10/40/7 and 10/41/7 (hypothetically) I know you can change them just wanted to know if that was correct
6 REPLIES
Patrick Wallek
Honored Contributor

Re: DS2100 connection

Yes you will should be OK. Even though both interfaces are on the same card, they should be seen as independent interfaces.
Eugeny Brychkov
Honored Contributor

Re: DS2100 connection

No, not OK. As soon as there's only one SCSI bus is running through DS2100 both controllers (or ports) should have DIFFERENT SCSI Ids. Both cards should be terminated
Eugeny
Alicia White
Esteemed Contributor

Re: DS2100 connection

The previous person who posted is correct: there is only 1 SCSI bus in the DS2100.

But to elaborate on what he said, I think it's important to point out a couple of things.

First, the second SCSI connection on the back of the system is provided so that you can daisy chain other SCSI devices from the DS2100. In fact, you can daisy chain up to 3 DS2100 units together.

However, if another device is not going to be daisy-chained from the DS2100, then the 2nd SCSI port must be terminated (this is because the DS2100 would be at the end of the SCSI bus).

See the user manual for more details.

You can see the PDF version of the user manual at:
http://h200005.www2.hp.com/bc/docs/support/SupportManual/lpg28796/lpg28796.pdf

Good luck,

Alicia
Vincent Farrugia
Honored Contributor

Re: DS2100 connection

Hello,

As Patrick said, you can leave them the same, since that dual-port SCSI card has its ports independant to each other, two buses if you like.

But I suggest you change one of them simply to keep track of "which is which" regarding buses. Simpler to se which bus is which if you change its id.

HTH,
Vince
Tape Drives RULE!!!
Bob_Vance
Esteemed Contributor

Re: DS2100 connection

Eugeny is correct -- NOT OK.

The DS2100 is a single bus; i.e., does not support split bus. Thus, the 2 HBAs on the bus must have different target IDs.

You can either daisy chain 3 DS2100's on a single initiator (HBA) or 2 with 2 initiators (because of the addressing scheme).
The disk target IDs (addresses) with 3 DS2100 units are:
0 2 4 6
8 10 12 14
9 11 13 15

I'm not sure whether the 2-HBA/2-unit limit is *strictly* true -- but that's what HP says. It seems to me that you could set one initiator to 7 (highest SCSI priority) and the other to 5 and still have 3 DS2100 units daisy chained. Of course, you probably wouldn't want to use slot 4 of the first DS2100 (ID 6), since it would have a better priority than the HBA at 5.

bv
"The lyf so short, the craft so long to lerne." - Chaucer
Brian M Rawlings
Honored Contributor

Re: DS2100 connection

I think there is general confusion about the DS2100 and DS2300 JBOD chassis, which is causing the "yes, this is fine" and "no, this won't work" answers.

Read up on these chassis, and it turns out the Eugeny and Bob are right, the DS2100 has only one SCSI bus in it, no split bus available. With one SCSI bus, if you hook two SCSI adapters to it with the same SCSI ID (7), very bad things will happen to your data. Likewise if you connect the single SCSI bus to both ports on a dual-port HBA. Unless you can set the Initiator ID on one of them to 6, it won't work at all.

Alternatively, the DS2300 DOES have a split-bus option, and everything you are asking about COULD be done in a DS2300. This chassis holds up to 14 drives, instead of 4, and is generally a higher-end solution, intended for split-bus mirroring, etc.

One other alternative is to use two DS2100 4-drive chassis, and connect each to a SCSI HBA. Then mirror from chassis to chassis, and you have true HA (unless you use one dual-port HBA).

Regards, --bmr
We must indeed all hang together, or, most assuredly, we shall all hang separately. (Benjamin Franklin)