Storage Works 5300 and Ultrium 960

[Adrian - Stockall]

Hello.
We have several Storage Works 5300 (C7508B) around the company with the hot plug Ultrium 960 array module (Q1540A) in them.

When we have two modules, in the same 5300 and daisy chain them together we get a problem. We can read an write to the far end tape drive (SCSI ID 4) but not to the near end module (SCSI ID 3). The Far end Tape drive is has a terminator plugged in (C2364A). The cable doing the daisy chain is
Connex HP DB68M to HP DB68M Ultra LVD SCSI cable
The cable from the near drive to the server is a 68 PIN VHDCI (m) - hd68 (341176-B21)

We are using a Dual Port Adpatec card Ultra 320 (2061000-R) and have another 5300 hanging of the 2nd port.

All of this is attached and installed on a DL380 G3 with 1gb of memory.

The HP tape tools are saying that it thinks the cabling is wrong. but we cannot see what is wrong.

Any Ideas.

The only things we have spotted, is on the inside the units, you can see the term power pins have been linked with together with the cable from the module holder. Could the Term Power jumper be casuing the Issue ?

[Heshmat]

LTO3 (960) native transfer with ATS (Adaptive Tape Speed) is 27 to 80 MB/s and compressed is double that (160MB/S, It is always recommeded to have each tape drive on a separate bus ultra4 (U320), there is a rule in LTT that checks for problems like this, here is the explanation of the rule.

Performance & Configuration Check
Looks for indications of Speed Negotiation problems, resulting in lower than expected performance.  Also checks that hardware Data Compression is enabled and that Prevent Media Removal is disabled.

Here is the link for compatibility.
Server: HP ProLiant DL380 G3 (Retired)
Tape drive: HP StorageWorks Ultrium 960

http://www.hp.com/products1/storage/compatibility/tapebackup/ISS/Detail/16-0024-0012.html

Hope this helps,

[Adrian - Stockall]

Hello again

AS you may note. we are not using the Internal SCSI to connect the Tapes drives. we have purchased an apatec card which support u320.

We have done some more testing and found that if you pull the far end module out of the 5300 the near end drive works fine.

To us the issue suggest that when to 960 modules are in the same 5300 and chained together, you can write to the near end Module.

Thie Link you sposted suggest using a seperate SCSI and seprate cage, which we are doing.

[Heshmat]

Have you tried connecting each port of the SCSI card to each one of the tape drives in the array without daisy chaining. just single tape drive, single bus one terminator for each of the tape drives in the array?

[Marino Meloni_1]

I have a question, you said that you cannot use the lto3 with id3 daisy chained with the lto id4. Can you explain what this mean? do you mean that starting two backup, only the first run? or do you mean you cannot detect the second LTO? what happens with the LTT tests? did they pass all, or only certain?
For how SCSI work, the unit in ID4 have higher priority than the one in ID3, so it may be that some command have priority for the drive is ID4, and as the lto3 could stream at around 80 MB/s writing to tape, ususaly the slower part of the scsi chain is the Host, and that is why the LTO3 in ID 4 will always be available to receive data. Then the scsi controller on the scsi bus probably is never free, and have to fill in the first drive with higher priority.
You can do a test, if you can (do not know now the 5300) change the ID number, and set the first at 1 instead of 4, then run the backup and see if the problem move to the second one.
Another test, (if you can do that on the 5300) is to not daisy chain the two lto3, and have each connected to one scsi controller.
This may be your problem, not sure, but may be. HP always recomend to connect only one LTO3 per scsi bus