aic7892 trouble

Martin Nilsson martin at
Tue Apr 22 04:24:25 PDT 2003

argo wrote:
> I have Adaptec U160 Host-Adapter with 2x Atlas 10k disks.When i copy
> large files (~700MB) then performance is pretty bad.I got only about
> 35MB/sec between those 2 disks.


The Atlas 10K3 disk have an outer STR of ~55MB/s and an inner STR of 
~35MB/s. The STR is the rate at which you can read the same track over 
and over again. In normal use you will have to reposition the heads from 
tack to track and the disk doing the writing will probably not be as 
fast as the one reading. For an indepth analysis of the Atlas 10K3 see:

What your test shows is that FreeBSD is very efficient and it does not 
degrade performance in any way. If you want a faster STR you have to buy 
newer disks or use RAID1 (or RAID5).


> Thanks in advance.
> ahc0: <Adaptec 19160B Ultra160 SCSI adapter> port 0xa000-0xa0ff mem
> 0xe2024000-0xe2024fff irq 11 at device 9.0 on pci0
> aic7892: Ultra160 Wide Channel A, SCSI Id=7, 32/253 SCBs
> da0 at ahc0 bus 0 target 0 lun 0
> da0: <QUANTUM ATLAS10K3_18_WLS 020W> Fixed Direct Access SCSI-3 device 
> da0: 160.000MB/s transfers (80.000MHz, offset 127, 16bit), Tagged
Martin Nilsson, CTO & Founder, Mullet Scandinavia AB, Malmö, SWEDEN
E-mail: martin at, Phone: +46-(0)708-606170,

Our business is well engineered servers optimized for FreeBSD and Linux.

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