Understanding the SCSI Passthru Drivers
NetBackup Media Manager provides its own driver for communicating with SCSI-controlled robotic peripherals.
This driver is called the SCSA (Generic SCSI passthru driver), also referred to as the sg driver.
To manage the sg driver
Perform the following steps as the root user.
1. Determine if an sg driver is loaded by using the following command:
/usr/sbin/modinfo | grep sg
141 fc580000 2d8c 116 1 sg (SCSA Generic Revision: 3.4d)
153 fc7fa000 1684 49 1 msgsys (System V message facility)
2. Remove the existing driver:
/usr/sbin/rem_drv sg
/usr/bin/rm -f /kernel/drv/sg.conf
Install SG Driver
To install the driver run the following command:
/usr/openv/volmgr/bin/driver/sg.install
Once the driver has been installed, it is not necessary to reboot the system or run the sg.install command during or after each system boot.
Configuring SG and ST Drivers
This procedure contains instructions for configuring the sg driver for SCSI targets 0 thru 6 and 8 thru 15 for fast or wide adapter cards.
In this procedure, you execute sg.build to add these targets to the st.conf, sg.conf and sg.links files. Adjust the -mt and -ml parameters to create the range of targets and LUNs required by your configuration.
To configure drivers
Execute the sg.build script to add target IDs 0-6, 8-15, and LUNs 0-1 to the following files:
/usr/openv/volmgr/bin/driver/st.conf
/usr/openv/volmgr/bin/driver/sg.conf
/usr/openv/volmgr/bin/driver/sg.links
/usr/openv/volmgr/bin/sg.build all -mt 15 -ml 1
The -mt 15 parameter specifies themaximum target ID that is in use on any SCSI bus (or bound to a fibre channel device).The -ml 1 parameter specifies the maximum target LUN that is in use on any SCSI bus (or by a fibre channel device).
The file /usr/openv/volmgr/bin/driver/st.conf is used to replace the following seven entries in the /kernel/drv/st.conf file:
name=”st” class=”scsi” target=0 lun=0;
name=”st” class=”scsi” target=1 lun=0;
name=”st” class=”scsi” target=2 lun=0;
name=”st” class=”scsi” target=3 lun=0;
name=”st” class=”scsi” target=4 lun=0;
name=”st” class=”scsi” target=5 lun=0;
name=”st” class=”scsi” target=6 lun=0;
Edit the /kernel/drv/st.conf file.
Place a # in column one of each line of the seven default entries.
The temporary file ./st.conf contains the entries that you need to insert into /kernel/drv/st.conf.
Reboot the system with the reconfigure option (boot -r or reboot — -r).
Verify that the system created device nodes for all the tape devices using the following command: ls -l /dev/rmt/*cbn
Install the new sg driver configuration.
/usr/bin/rm -f /kernel/drv/sg.conf
/usr/openv/volmgr/bin/driver/sg.install
when run sg install command sg.conf will copy to /kernel/drv/sg.conf
and sg.links will copy to /etc/devlink.tab
Verify that the sg driver found all the robots, tape drives,
The script /usr/openv/volmgr/bin/sg.build adds the proper entries to the sg.links and sg.conf files. Before running the script, make sure that all devices are powered on and connected to the HBA.An example of the additional entries in /usr/openv/volmgr/bin/driver/sg.conf
follows:
name=”sg” parent=”fp” target=0 lun=0 fc-port- wwn=”22000090a50001c8″;name=”sg” parent=”fp” target=0 lun=1 fc-port-wwn=”22000090a50001c8″;
An example of the additional entries in /usr/openv/volmgr/bin/driver/sg.links
follows:
type=ddi_pseudo;name=sg;addr=w22000090a50001c8,0; sg/c\N0t\A1l0type=ddi_pseudo;name=sg;addr=w22000090a50001c8,1; sg/c\N0t\A1l1
Preventing Possible System Problems
VERITAS recommends adding the following forceload statements to the /etc/system file. These statements prevent the st and sg drivers from being unloaded from memory
forceload: drv/st
forceload: drv/sg
Other statements may be necessary for various fibre channel drivers, such as the following example for JNI drivers. This statement prevents the named driver from being unloaded from memory.
forceload: drv/fcaw
SSO Configurations With More Than 16 Tape Drives
When the number of tape devices that are configured approaches 16, changes in tape device status may not be visible to all media servers in a Shared Storage Option (SSO) configuration. This is because the default maximum size of IPC message queues may not be large enough.
VERITAS recommends adding the following statements to the /etc/system file. These statements increase the maximum number of messages that can be created, and the number of bytes per queue. A reboot is necessary for the changes to take effect.
set msgsys:msginfo_msgtql=512
set msgsys:msginfo_msgmnb=65536
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