Relationships between config files

[rjrumfelt]

I'm not sure if this is the forum to post this, but it is in part related to NetBackup.

I am always looking for an opportunity to learn more about unix, and we recently had to build an sg driver for a new installation we're doing, and it brought up some questions that I would like to know more about.  Primarily, the relationships between the files used to help creage the sg.conf file.

The one that is most intriguing is the sg.links file.  Can anyone explain the sections of an entry in the sg.links file, and what the sg.links file actually does?

What information does the following line contain:

type=ddi_pseudo;name=sg;addr=0,0;     sg/c\N0t010

And how does that information relate to st.conf, sg.conf, and /dev/rmt?

Also, it appears that the /kernel/drv/sg.conf file looks very similar to the st.conf file.  Why doesnt the sg driver just use the st.conf file?

[Marianne · Accepted solution]

The sg.links is used to build entries in /etc/devlink.tab. The devlink.tab is used to build sg.conf.
The one device that absolutely needs the sg driver is the robotic device. The O/S does not have any facility to create a robotic device file (nothing in st.conf).
The Device Config Guide says that the sg driver is required "for full feature support". The device config wizard will only pick up all devices if sg can see/access them.
I have also seen a situation where backups worked fine with /dev/rmt  (st driver using st.conf) entries, but a restore failed. The bptm log was complaining about an sg path that could not be found. (Restore worked fine after rebuilding sg. A Solaris patch broke the sg driver.)

Extract from device config guide:
NetBackup provides its own driver to communicate with SCSI-controlled robotic peripherals. This driver is called the SCSA (generic SCSI pass-through driver), also referred to as the sg driver.
Note: Because NetBackup uses its own pass-through driver, NetBackup does not support the Solaris sgen SCSI pass-through driver.
For full feature support, NetBackup requires the sg driver and SCSI pass-through device paths.

[rjrumfelt]

This definately points me in the right direction.  Now I'll go research devlink.tab