Drivers driving crazy !!

[nbuno]

Guys,

i went through the Netbackup Device Configuration guide but couldn't understand even the half of it.

can you tell me in simple words please that once every cabelling and stuff (media server to library/library to drives etc) is in place the after that what we need to do to configure our tape drives/robotic library ?

what are sg and st drives and conf files (sg.conf & st.conf) ?What are they used for ?Do we have to mess with them each time we add or replace a drive/robot or troubleshoot a device related issue ?

 extracts like the one below from NBU documentation is driving me nuts !!!!!!!

"Configuring the sg and the st drivers

You must configure the Sun st driver for use with the devices attached to each

Solaris host that functions as a NetBackup media server.

You may have to configure the sg driver, as follows:

■

If the host requires more SCSI addresses than targets 0 through 6 and LUNs 0 and 1, you must configure the sg driver. (By default, NetBackup configures the sg driver for SCSI targets 0 through 6 and LUNs 0 and 1.) The two most common reasons LUNs greater than 1 are required are for virtual tape libraries and SCSI to FC bridges. These devices use one target ID with multiple LUNs for the devices in or connected to them.

■

If the host contains a Fibre Channel Protocol (FCP) host bus adapter (HBA), you must configure the sg driver. FCP HBAs include StorEdge Network Foundation HBAs.

If the host requires only SCSI targets 0 through 6 and LUNs 0 and 1, you do not have to configure the sg driver. However, you still must complete the configuration procedure so that the st driver is configured and the device files are created."

I have a peanut size intellect so i am really really expecting something very simple to understand :(

--thanks in advance !!

[Marianne]

Long story short:

The st driver is the OS driver that creates device entries in /dev/rmt.

NBU will use the *cbn device names. As a start do a long listing of cbn entries in /dev/rmt:
# cd /dev/rmt
# ls -l *cbn

Check that this output sees the correct amount of tape drives.
If not, please tell us what kind of hba you are using, the driver used and OS version.

If output is correct, you need to check if the NBU sg driver can see all the tape drives and the robot (if it is zoned to this particular server):
# /usr/openv/volmgr/bin/sgscan

If all the drives are not displayed in the output, go back to the /dev/rmt output to determine the amount of targets and luns. (http://www.symantec.com/docs/TECH71073)
For example : (extract from old NBU 3.4 TN):

lrwxrwxrwx    1 root     other          45 Apr 10 12:25 0cbn -> ../../devices/pci@1f,4000/scsi@4,1/st@2,0:cb
lrwxrwxrwx    1 root     other          45 Apr 10 12:25 1cbn -> ../../devices/pci@1f,4000/scsi@4,1/st@3,0:cbn
lrwxrwxrwx    1 root     other          45 Apr 10 12:25 2cbn -> ../../devices/pci@1f,4000/scsi@4,1/st@13,1:cbn
lrwxrwxrwx    1 root     other          45 Apr 10 12:25 3cbn -> ../../devices/pci@1f,4000/scsi@4,1/st@20,0:cbn
   

Note: The strings st@2,0 st@3,0 st@13,1 and st@20,0 at the end of the device paths.  These are the scsi target and lun values.
    Also Note:  The target and lun values for "st@?,?" are in hexadecimal format, NOT decimal.
        /dev/rmt/0cbn has target 2 and lun 0 (st@2,0).
        /dev/rmt/1cbn has target 3 and lun 0 (st@3,0).
        /dev/rmt/2cbn has target 19 and lun 1 (st@13,0).
        /dev/rmt/3cbn has target 32 and lun 0 (st@20,0).

So - in the above example output, your maximum target number is 32 and max lun is 1.

Your device names might also be in this type of format, depending on the hba driver (wwn instead of target number):

lrwxrwxrwx   1 root     root          88 Nov 22 10:07 0cbn -> ../../devices/pci@0/pci@0/pci@8/pci@0/pci@a/SUNW,qlc@0/fp@0,0/st@w2c3b08001b1070e4,0:cbn
lrwxrwxrwx   1 root     root          88 Nov 22 10:07 1cbn -> ../../devices/pci@0/pci@0/pci@8/pci@0/pci@a/SUNW,qlc@0/fp@0,0/st@w243b08001b1070e4,0:cbn

all lun numbers are 0.

In the above example, the default number of targets and luns will be fine (max targets 6, max luns 1).

Summarized version of steps to rebuild sg driver:

# cd /usr/openv/volmgr/bin/driver

# /usr/openv/volmgr/bin/sg.build all -mt <32> -ml <1>      ### Use /dev/rmt/*cbn entries to determine number of targets and luns###

(Install the new sg driver configuration:)

# /usr/bin/rm -f /kernel/drv/sg.conf

# /usr/openv/volmgr/bin/driver/sg.install

# /usr/openv/volmgr/bin/sgscan

(This time sgscan should display robot and tape drives)

[mph999]

Have a technote:

http://www.symantec.com/docs/TECH125956

To add to Mariannes informative post, the sg driver is used in Solaris to pass commands to the tape drives that can't be passed using the st driver, for example 'mode sense'.

Martin