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SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

SemihBATTAL
Advisor

SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

Hi,

I submitted this question yesterday but it simply got lost, sorry for the duplication if it decides to show up in the forum.

We have an RX2620-2 server with an LVD/SE HDTS68 connector at the back, connected to a 1x8 G2 Autoloader ( with Ultrium920 drive ) with the same type connector through a C2924C cable.

Is this an acceptable configuration ?
The Autoloader documentation says that:
"
NOTE: The host bus adapter should be Low Voltage Differential Signaling (LVDS). A Single-Ended (SE) SCSI host bus adapter works, but severely degrades performance and limits cable length. If any SE devices are on the same parallel SCSI bus, all of the devices on the parallel SCSI bus slow to SE speed, which severely degrades performance. Never attach an LTO-3 or LTO-4 tape drive to an SE SCSI bus.
"

Does this mean our configuration is "bad" ?
9 REPLIES
Curtis Ballard
Honored Contributor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

Your configuration is correct. The LVD/SE indicates that HBA can run in EITHER mode and which mode is determined by what is connected.

If you connect any SE devices the HBA switches to SE and everything has to run SE in which case performance will be poor. As long as only LVD devices are present the HBA will run in LVD mode.

You don't say it, but it sounds like the 1/8 G2 is the only device on the bus which is the optimal configuration.
SemihBATTAL
Advisor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

Thank you for your reply.
There are no other devices on the secondary channel of the SCSI bus, just the autoloader. The two internal disks are on the primary channel.
One other thing which is puzzling me is, I changed the suspect SCSI cable with a new one recently and now the green led on terminator turns off when the SCSI cable is plugged in, it is on when there is no connection, is this normal ? There are no SCSI bus error messages in any of the logs.
Curtis Ballard
Honored Contributor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

Most terminators are green when running in LVD mode and orange or off when running in SE mode. If your terminator LED isn't green that may indicate a problem. You can use the library web interface or L&TT on the backup server to pull a support ticket from the drive and that will include information about what mode the drive is using.
SemihBATTAL
Advisor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

I have just sent the autoloader and drive support tickets to HP. I'll be back with the results when HP responds...
Dennis Handly
Acclaimed Contributor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive?

>I submitted this question yesterday but it simply got lost

Are you talking about your other topic:

http://h30499.www3.hp.com/t5/Integrity-Servers/SCSI-compatibility-between-RX2620-2-core-IO-SCSI-and-1x8-G2/m-p/4605933

SemihBATTAL
Advisor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

Yes...
I don't remember a 24 hour delay in any of my previous posts.
Dennis Handly
Acclaimed Contributor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

>I don't remember a 24 hour delay in any of my previous posts.

Delay in what, replies? Remember in the forum, you are depending on the kindness of strangers.
SemihBATTAL
Advisor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

No, I meant the delay in my initial question appearing in the forum. I waited for almost 20 hours before submitting my question again to find my first post suddenly showing up. Could there be some sort of manual screening for the questions ?

About the "strangers":
I can't thank them enough for their sincere help. Some even involved people from the industry to solve my problems. I wish I knew enough to be one of those "strangers".
Dennis Handly
Acclaimed Contributor

Re: SCSI LVD/SE bus connected to LVD Ultrium920 drive ?

>I meant the delay in my initial question appearing in the forum.

There is no delay. If it isn't there right away, it was never accepted. Especially if there are no error messages.
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