Abysmal Tape Drive Performance on a 2850

[Kuba Ober]

Hi,

I think I have the same problem that someone else had:
I have a 2850 w/PERC4 and a Dell-branded VS160 tape drive attached to it.

After upgrading from CentOS 4.4 to CentOS 5, the tape drive performance got 
*abysmal*. It cannot maintain streaming even if I do
dd if=/dev/zero of=/dev/nst0 bs=65536, it also won't accept any block size 
larger than 65536. On CentOS 4.4, it'd happily take 1MB blocks, on CentOS 5 
dd barfs with "device busy" on bs>65536.

On 4.4, the drive was doing >10megabytes/s, now it barely does 1-2.

Is this a known problem? Any workarounds?

Cheers, Kuba

02:0e.0 RAID bus controller: Dell PowerEdge Expandable RAID controller 4 (rev 
06)

Host: scsi0 Channel: 00 Id: 06 Lun: 00
  Vendor: PE/PV    Model: 1x6 SCSI BP      Rev: 1.0
  Type:   Processor                        ANSI SCSI revision: 02
Host: scsi0 Channel: 01 Id: 06 Lun: 00
  Vendor: QUANTUM  Model: DLT VS160        Rev: 3200
  Type:   Sequential-Access                ANSI SCSI revision: 02
Host: scsi0 Channel: 02 Id: 00 Lun: 00
  Vendor: MegaRAID Model: LD 0 RAID1  139G Rev: 522A
  Type:   Direct-Access                    ANSI SCSI revision: 02