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Tape configuration lost on reconfiguration reboot

Created: 21 Feb 2013 • Updated: 25 Apr 2013 | 8 comments
This issue has been solved. See solution.

Hello,

I am unix admin. I went into a situation where looking for help for permanent solution.

Unix SA performed reconfiguration reboot to fix disk issue on Netbackup media server. After reboot, we found all tape drives were visible at OS leve ( cfgadm ) however, Netbackup SA was missing half of tapes in tapes configuration. Lateron, Netbackup SA had to perform tapes reconfiguration to get all tapes back to availability.

We understand during reboot, hardware device id got changed for few of tapes and hence impacted tapes configuration for netbackup.

How can we make device id persistent for tapes during reboot so that we dont face this issue on next reboot or reconfig reboot ?

Appreciate all response in advance !

Regards,

~Anoop

Operating Systems:

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Nagalla's picture

Persistance binding is required at OS level to make sure that the Drive paths are not chaning...

you would need to check the related OS technotes about how to make a persistant  binding.

SOLUTION
Noor Toorabally's picture

On solaris you need to modify the devlink tab (/etc/devlink.tab) so that the /dev/rmt/# remains the same for specific tapes.

Eg of devlink.tab:

type=ddi_pseudo;name=sg;addr=w20010013214436b6,2a;      sg/c\N0t\A1l42

See the document below for complete guide:

http://docs.oracle.com/cd/E19082-01/820-3070/agkci/index.html

 

Hope this helps

Yasuhisa Ishikawa's picture

First of all, check if broken tape device links existed at that time. It sometimes happen that broken link is removed during reconfiguring boot and link name for actual devices become adjusted.

For example, when /dev/rmt/0 is broken link and /dev/rmt/1 is link for actual device, broken link will be removed and link for actual device is renamed to /dev/rmt/0 during reconfiguration. This lead mismatch between OS configuration and NetBackup device managenet. SO, it is very important to keep device links clean anytime.

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Marianne's picture

I agree that Persistent Binding needs to be done.

You need to first of all determine which make/model HBA is used for tape access.

Configure Persistent Binding using hba tool or by editing the /kernel/drv/xxxx.conf. You can find details on the web site of HBA manufacturer (e.g. Qlogic or Emulex).

Supporting Storage Foundation and VCS on Unix and Windows as well as NetBackup on Unix and Windows
Handy NBU Links

Anoop_Kumar's picture

Hello,

Thanks for very useful information provided.

I see /etc/devlink.tab file is existing. Latest one is created on Feb 14 after reboot time. Is there possibility, even if devlink.tab exists, reconfig reboot can affect tape configuration ?

As per below output, I see there was devlink.tab before reboot, then why it impacted tapes to miss after reboot ?

 

 

#> ls -al /etc/devlink*
-rw-r--r-- 1 root other 10827 Feb 14 09:24 /etc/devlink.tab
-rw-r--r-- 1 root isd 9390 Feb 14 09:24 /etc/devlink.tab.02-14-13-09:24:22
-rw-r--r-- 1 root root 4148 Feb 17 2010 /etc/devlink.tab.02-17-10-20:16:25
-rw-r--r-- 1 root root 6948 Oct 2 2008 /etc/devlink.tab.10-02-08-12:23:24
-rw-r--r-- 1 root root 7429 Oct 2 2008 /etc/devlink.tab.10-02-08-20:11:39
-rw-r--r-- 1 root root 6256 Nov 3 2010 /etc/devlink.tab.11-03-10-19:16:11
-rw-r--r-- 1 root root 6256 Nov 3 2010 /etc/devlink.tab.11-03-10-19:23:16
-rw-r--r-- 1 root root 6256 Nov 27 2010 /etc/devlink.tab.11-27-10-17:27:20
-rw-r--r-- 1 root root 6256 Nov 27 2010 /etc/devlink.tab.11-27-10-17:39:43
-rw-r--r-- 1 root root 9390 Dec 2 2010 /etc/devlink.tab.12-02-10-17:04:38
-rw-r--r-- 1 root root 6896 Dec 19 2006 /etc/devlink.tab.12-19-06-12:15:32

 

~Anoop

Yasuhisa Ishikawa's picture

hardware configuration exactly, exactly, same with before? Any change on cabling, HBA bus slot, SCSI ID, WWN? Using 3rd party FC HBA without persistent binding?

If yes(completely same), I doubt broken rmt links generated by hardware configuration change without reconfigure boot.

BTW, How "ls -l /dev/rmt" looks like?

Authorized Symantec Consultant(ASC) Data Protection in Tokyo, Japan

Noor Toorabally's picture

Even though the /etc/devlink.tab exists, it would not by default contain the rules for tape devices, and hence the devfsadm command which runs while reconfiguration reboot will automatically create links for tape devices. For the binding to be persistant and not to change after a reconfiguration reboot, you need to add the rules manually for each tape device in the devlink.tab

Anoop_Kumar's picture

Hello Noor,

Thanks for your great help and advise on this so far.

Below is some output from server rmt devices and devlink file. Does it say there is no rule defined for tapes ? I see a lot of entries with wwn in it.

 

/#> ls -al /dev/rmt/4
lrwxrwxrwx   1 root     root          77 Feb 13 19:10 /dev/rmt/4 -> ../../devices/pci@780/pci@0/pci@8/SUNW,qlc@0,1/fp@0,0/st@w500507630f5bf614,0:

/#> grep w500507630f5bf614 /etc/devlink.tab
type=ddi_pseudo;name=sg;addr=w500507630f5bf614,0;       sg/c\N0t\A1l0
type=ddi_pseudo;name=sg;addr=w500507630f5bf614,1;       sg/c\N0t\A1l1
/#>

 

If I follow below link for creating rules for persisting binding on tapes, where can I find currently defined tape numbers to set in rules in devlink file?

http://docs.oracle.com/cd/E19253-01/820-1931/agkck/index.html

Regards,

~Anoop

~Anoop