Tape Drive on SCSI RAID Controller?

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jayIT

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Feb 23, 2006
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I am seeing horrid performance on my backups since I built my server.

The server is a Dell PowerEdge 2850. OS = Win Server 2003 Enterprise (all updates).

My tape drive is an HP Ultrium LTO 4 SCSI internal. However, it's actually external to the server, and installed in a rack box. So it uses the external 68-pin VHDCI.

The card it's connected to is a PERC 4/DC U320 PCIe SCSI RAID controller from DELL. It's on channel 1. Nothing else is connected to this controller. The HD array uses the built in RAID controller on the mobo.

I'm using Symantec Backup Exec 12. I've tried both HP and Symantec drivers and I'm still only getting about 80 MB/min. That's unbelievably slow.

Now my question: is the slow performance due to the fact that the tape drive is connected to a RAID controller instead of a plain old U320 SCSI HBA? I wouldn't have thought it would make that much of a difference, but maybe I don't understand the processing differences between the two types of SCSI cards. I thought there was only a problem with this setup if a HD array was also being used on the same controller.

Can someone explain if this is a problem, and why?

Thanks!
 
Joined
Dec 31, 2004
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Do you have an extra scsi controller card besides the raid card you can test it with?
 

jayIT

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Feb 23, 2006
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yeah I have an extra. It's a LSI U320 SCSI HBA. I'll probably try that, but I have to wait until after hours one day so I can take the server down and swap the hardware. That's such a pain.

Anyone have a definitive answer on the RAID controller question?
 

jayIT

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Feb 23, 2006
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35
bump. need another opinion or someone who has seen this problem.
 

leroys1000

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Aug 15, 2007
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Only things I can think of.
Make sure device ID is set on the tape drive and make
sure it is not the same as the controller card.
Make sure to terminate the cable with the proper terminator.
Usually goes on the last connector on the cable.

I use an external hard drive as they are inherently faster,due
to being nonlinear.
 
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Oct 7, 2008
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Not a solution but we suddenly have exactly the same issue on BE11d, with Dell PowerEdge 2900. The card is LSI Logic SCSI 320-I. We have switched cards and drivers without solution.

This problem has just happened in the last couple of days. Previously we were getting 500-700MB/min, now 100MB/min.

Nothing was changed on the system, we are puzzled.
 

jayIT

Thread Starter
Joined
Feb 23, 2006
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35
I found the solution to this.

The problem must have been the fact that I was using a RAID controller to support a tape drive. I bought an HP (LSI manu) U320 G2 SCSI HBA, and saw my backups go from 80 mb / min to 3000 mb / min! Verify reached almost 8000 mb / min. Needless to say, I can now backup my data 37x faster.

Let this be a note: SCSI RAID controllers are not good for connecting tape drives. Instead, go with a plain old SCSI HBA.
 
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