Re: [Networker] Windows2003 R2 change tape order at boot
2007-09-06 16:33:10
Hi Gaddy
You make a great point!
http://download.qlogic.com/drivers/5419/QLogic_Solaris.pdf describes Qlogic's
persistent binding implementation. The persistence implemented by the FC HBA
driver provides the binding of the Fibre Channel entity (pairing the WWNN/WWPN
of the storage and the host HBA number) to a SCSI logical unit number (LUN).
That's it; it doesn't deal with the logical device naming at all.
ftp://ftp.software.ibm.com/storage/devdrvr/Doc/IBM_Tape_Driver_IUG.pdf
describes (among other things) the IBM tape driver's support for persistent
naming on AIX, HP-UX and Solaris (note that Windows is not in that list).
However, in the README file for the latest IBM tape driver for Windows
(ftp://ftp.software.ibm.com/storage/devdrvr/Windows/Win2003/Latest/IBMTape.W200x.Readme.txt),
the following appears:
"Version 6.1.6.2 and later versions of the device driver have an option for
enforcing file names for tape drives that will persist across reboots of the
operating system. For example, if your tape drive has the name \\.\tape3 and
the persistent naming option is used, then \\.\tape3 will be reserved for use
by that device after an operating system reboot. To take advantage of this
feature, place a DWORD value in the registry called PersistentNaming and assign
it a value 1 at:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ibmtp2k3
and reboot your system."
So, the IBM tape driver DOES provide the LUN-to-logical device mapping that
Pierpa seeks.
I'm sure there are other methods of providing logical device-level persistent
mapping. On Linux systems with the 2.6 kernel, udev provides persistent naming
(among other things); see http://www.reactivated.net/writing_udev_rules.html
for a primer.
If you know of other ways to provide logical device-level persistent mapping,
please share them with this list.
Thanks
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
-----Original Message-----
From: EMC NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] On
Behalf Of Gaddy
Sent: Thursday, September 06, 2007 11:22 AM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: Re: [Networker] Windows2003 R2 change tape order at boot
AFAIK persistent binding on the FC-HBA affects only the physical addresses
of the devices, scsidev AT bus.target DOT lun.
So you can easily put that addressing scheme into a fixed sequence.
Unfortunately NetWorker does not use physical addresses on Windows*,
but logical addresses like \\.\TapeX.
Logical to physical address resolution will be done on "1st come, 1st
serve", which should be no problem, as long as all "persistent bound"
devices are online. But, if for some reason (powered off,
disconnected, ...) one physical address could not be resolved, the logical
address is given to the next physical device.
This is the way MS works (from my POV).
MS knowledgebase article --> http://support.microsoft.com/kb/873337/en-us
( Thanks Michael ) could (I've never tested this, and in fact have not
even known about before reading Michaels comment) changes this behaviour
and adds probably some "logical persistent binding" to Windows2003.
I'd like to know, if someone has played a bit with that fix successfully.
Gaddy
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