Hello,
apologies in advance - this may be a bit off topic, but I guess I find
most experts for such a problem on this list...
I see very poor performance with HP Ultrium LTO3 drive, which is
attached over SCSI to a Linux box (using a Adaptec 2940 Ultra SCSI
adapter). It seems I cannot get more than about 8.8 MBytes/s for
either writing to or reading from the drive.
Looking around, I see this information in /proc/scsi/aic7xxx/3 :
...
Target 5 Negotiation Settings
User: 40.000MB/s transfers (20.000MHz, offset 127, 16bit)
Goal: 10.000MB/s transfers (10.000MHz, offset 15)
Curr: 10.000MB/s transfers (10.000MHz, offset 15)
Channel A Target 5 Lun 0 Settings
Commands Queued 20
Commands Active 0
Command Openings 1
Max Tagged Openings 4
Device Queue Frozen Count 0
...
Am I understanding this correctly that the SCSI adapter is set to
10 MB/s transfers only? That would certainly expolain the transfer
rates I'm observing...
Is there any way to tweak these settings in Linux? I alreay checked
in the SCSI adapter's BIOS settings, but there are no indications for
auch a limitation.
[Yes, I am aware that the Adaptec 2940 is not exactly new. But I
should get more than 8.8 MB/s out of it, should I not?]
Any help welcome. Thanks in advance.
Best regards,
Wolfgang Denk
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd AT denx DOT de
If the odds are a million to one against something occuring, chances
are 50-50 it will.
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