Infodoc ID   Synopsis   Date
21082   How to reduce the speed of a controller or disk using a glm.conf file   3 Jan 2000


Description  
To reduce an UltraSCSI controller (glm), and all disks attached to 
operate at Fast/Wide speed, create a file `/kernel/drv/glm.conf' 
with an entry like this.

name="glm" parent="/pci@6,4000"
     unit-address="2"
     scsi-options=0x3f8;
   name="glm" parent="/pci@6,4000"
     unit-address="2,1"
     scsi-options=0x3f8;

This example is for an UltraSCSI controller in slot 3 of an 
Ultra Enterprise (UE)450 (pci@6,4000/scsi@2).  You could also reduce
the speed to one specific disk (target) on a controller by creating
a /kernel/drv/glm.conf file with an entry like this.

name="glm" parent="/pci@6,4000"
     unit-address="2"
     target1-scsi-options=0x3f8;

The above would force the target 1 disk on the UltraSCSI controller in slot 3
of a UE450 to run at Fast/Wide speed and all other disks attached to this 
controller would run at UltraSCSI speed.

To reduce the transfer rate for multiple targets on the same controller:

Assume there are two DLT4x00(fast SCSI, 10MB/s) tape drives attached to a 
fast wide SCSI (20MB/s) controller on an e450 that is giving some SCSI 
timeout errors.  A solution known to work, is to reduce the transfer
rate for the two tape drives explicitly.  In this example, the tape drives 
are at SCSI targets 4 and 5 attached to the onboard SCSI port of the e450.  
The entry below could be used to in a /kernel/drv/glm.conf file to resolve 
the timeouts.

name="glm" parent="/pci@1f,4000"
    unit-address="2"
    target4-scsi-options=0x1f8
    target5-scsi-options=0x1f8;


This method has been known to solve the following errors: 

    SCSI transport failed 
    Connected command timeout 
    Reducing synchronous transfer rate 
Applies To Hardware, Operating Systems/Solaris/Solaris 2.x
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