Q: What is the correlation between Linux udev rules and the NetWorker jukebox 
resource 'Use Persistent Binding' attribute? What udev rules have to be 
configured?
A: The udev rules that ship with certain Linux distributions automatically 
create persistently-named symbolic links in certain locations (each 
distribution seems to be slightly different). NetWorker for Linux V7.4 SP2 and 
later has been enhanced to look for several of these locations and, if the 
jukebox attribute 'Use Persistent Names' is selected, NetWorker will use these 
persistently-named symbolic links in its configuration.
NetWorker for Linux V7.4 SP2 and later have this enhancement: 
        "New media library attribute and addition to the device configuration 
wizard 
        A new attribute, Use Persistent Names, has been added to the General 
tab of the
        Storage Node resource for NetWorker release 7.4 Service Pack 2. When 
this
        attribute is selected, configuration of a tape library (by using 
autoconfiguration
        from NMC) on a Linux host attempts to use the symbolic name for media 
library
        control ports and devices controlled by udev on Linux. When using the 
device
        configuration wizard, you can also select this option during 
autoconfiguration of
        devices." [from the EMC® NetWorker Release 7.4 and Service Packs 
Release Notes, available at http://powerlink.emc.com at Home 
<http://powerlink.emc.com/km/appmanager/km/secureDesktop?_nfpb=true&_pageLabel=homePgSecureContentBk>
  > Support 
<http://powerlink.emc.com/km/appmanager/km/secureDesktop?_nfpb=true&_pageLabel=--NULL--&internalId=0b01406680024e1b>
  > Technical Documentation and Advisories 
<http://powerlink.emc.com/km/appmanager/km/secureDesktop?_nfpb=true&_pageLabel=--NULL--&internalId=0b01406680024e23>
  > Software ~ J-O ~ Documentation > NetWorker 
<http://powerlink.emc.com/km/appmanager/km/secureDesktop?_nfpb=true&_pageLabel=--NULL--&internalId=0b0140668015b2d3>
  > NetWorker for Linux 
<http://powerlink.emc.com/km/appmanager/km/secureDesktop?_nfpb=true&_pageLabel=--NULL--&internalId=0b0140668015b2df>
  > 7.4 & Service Packs]
So, if you either (1) have a Linux distribution with a 'working' version of 
udev or (2) you install a working version of udev, and if you install NetWorker 
V7.4 SP2 or later and if you select the 'Use Persistent Names' attribute for 
the jukebox before you do Scan for devices in NMC, then NetWorker will use 
these automatically-generated-by-udev persistently-named symbolic links.  
A key point here is that no udev rules need to be created by the user; the 
existing rules that come by default with these distributions provide all of the 
necessary machinery.
I confirmed recently that following environments create persistently-named 
symbolic links in /dev/tape/by-id and/or /dev/generic/by/id:

SLES 9 SP4
SLES 10 SP2
RHEL 4.7 (*requires adding the line 'options=-g -u' to /etc/scsi_id.conf)
RHEL 5.3

See the following Red Hat document for more information.
http://rhn.redhat.com/errata/RHBA-2008-0740.html
http://rhn.redhat.com/errata/RHBA-2008-0374.html 

Hope this helps.
tl

Terry Lemons
Backup Platforms Group
EMC² 
where information lives
4400 Computer Drive, MS D239
Westboro MA 01580
Phone: 508 898 7312
Email: Lemons_Terry AT emc DOT com

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