Dear misc readers, Recently I upgraded the SCSI card and the tape drive in my home server to the following:
mpi0 at pci1 dev 2 function 0 "Symbios Logic 53c1030" rev 0x08: apic 3 int 7 mpi0: 0, firmware 1.3.39.0 scsibus2 at mpi0: 16 targets, initiator 7 st0 at scsibus2 targ 3 lun 0: <HP, Ultrium 3-SCSI, G64D> SCSI3 1/sequential removable naa.500110a0010dafe6 mpi0: target 3 Sync at 10MHz width 16bit offset 64 QAS 0 DT 0 IU 0 According to HP the tape drive, a StorageWorks Ultrium 960, should support bus speeds up to U320 allowing the tape drive to back up data at speeds up to 80MB/s. As a result I believe the tape drive is "misprobed" as only supporting a 10MHz bus speed; I would have expected the mpi(4) driver to report a bus speed of 160MHz based on HP's claims. The low bus speed negotiated between the SCSI card and the tape drive unfortunately causes the tape drive to back up data at roughly 16-17MB/s instead of the expected 30-60MB/s (*). This is causing full backups to take way longer than I hoped for. Would it be possible that the "misprobing" is caused by the mpi(4) driver probing the bus speed at attachment time instead of media insertion time? Prior to using a mpi(4) SCSI card, I used a siop(4) card (see also attached full dmesg). This card would only negotiate a speed with the tape drive when a tape was inserted into the drive. Kind regards, Mark (*) I am using Ultrium 2 tapes in a Ultrium 3 tape drive which prevents the tape drive from reaching its maximum speed of 80MB/s. According to HP however the tape drive should be able to reach speeds in the range 30-60MB/s depending on the amount of compression achieved.
dmesg.out
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