scsi tape drive slow in freebsd

[Julian H. Stacey]

Frank Mancuso wrote:
> hello there I have a scsi tape drive which is made by seagate python.
> It is a scsi 2. normally in linux or windows it takes about 2 hours
> and 30 mins to restore or backup. I just installed freebsd 4.11 and I
> started to restore and it has been running for more then 10 hours ..
> 
> this is my dmesg
> 
> ahc0: port 0xe800-0xe8ff mem 0xe1811000-0xe1811fff irq 11 at device 12.0 on pci0
> aic7860: Ultra Single Channel A, SCSI Id=7, 3/253 SCBs
> Waiting 15 seconds for SCSI devices to settle
> sa0: Removable Sequential Access SCSI-2 device
> 
> I had to recompile the kernel to support my dual P3 I was wondering if
> maybe I had to add something in the kernel to speed this up..
> 
> thanks.

perhaps
mt blocksize 512
or 
mt blocksize 0

I used to see vast slow down if reader wasnt reading how how the
writer wrote it.
Also think blocking with tar if that's what your using eg 
	-b 10k or 60k or whatever
Your ear should tell you if it's streaming or stop starting.

Ref man mt

-- 
Julian Stacey     Consultant Systems Engineer, Munich.     http://berklix.com
Mail in Ascii (Html = Spam).  Ihr Rauch = mein allergischer Kopfschmerz.