SCSI address of autochanger changes after reboot

Question

We are using redhat AS 4 update 4 using a 2.6 kernel. We want to upgrade from networker 7.2.1 to 7.3.2 on a 2.6 kernel. The problem is that the scsi address of our IBM 3584 autochanger changes after a few reboots. Initially the scsi address obtained with the inquire command is:

scsidev@2.2.1:IBM 03584L32 5770|Autochanger (Jukebox), /dev/sg9
S/N: 0000000189730401
ATNN=IBM 03584L32 0000000189730401

After a few reboots it changes to :

scsidev@2.1.1:IBM 03584L32 5770|Autochanger (Jukebox), /dev/sg9
S/N: 0000000189730401
ATNN=IBM 03584L32 0000000189730401

As it changes from scsidev@2.2.1:IBM to scsidev@2.1.1:IBM, we are unable to properly operate the autochanger. AutoChanger is SAN attached and as we are using Emulex HBA card on a 2.6 kernel, persistent binding is no longer supported. Udev is used instead for persistent binding purposes. However, we are unable to use udev to persistently bind scsidev@2.1.1 as we believe that it is generated by inquire command which can only be understood in Networker context.

Does anyone out there with Kernel 2.6 with Emulex HBA faced with this problem?

ble1 · Answer

Persistent binding is not supported? That's strange one. Can you explain what udev is? inquire has nothing to do with library address - it just reports it.

shutchins · Answer

This summer emulex stopped supporting persistent bindings due to pressure from redhat.
You must now use the open source method via udev. udev allows Linux to have a dynamic /dev directory and it provides the ability to have persistent device names.

I'm using redhat AS4 with emulex lpe1150 cards and Networker 7.3.2 and I'm faced with the same issue. It was so much easier just using the persistent binding features via hbaanywhere!

This may help
http://www.emulex.com/pdfs/wp_linux26udev.pdf
http://reactivated.net/writing_udev_rules.html
http://webpages.charter.net/decibelshelp/LinuxHelp_UDEVPrimer.html

ylam1 · Answer

Hi does the scsi address autochanger changes after reboots? If so how do you persistently bind the scsi address using udev. From what I gather if networker refers to the autochanger through /dev/sg9, then udev can be used for persistent binding. But scsi@2.1.1 is used instead and I do not have a clue on how to go about doing that.

How about using SuSe Enterprise Linux 9 since it was Redhat who pressured Emulex? Anyone can shed some light?

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ble1 · Answer

Thanks for link... I didn't read them yet, but this is just because I'm travelling right now and have limited time... But I think I figured out from last Chang's post on how it works... it is method like we have in Tru64 where for example you will have library persistent on /dev/changes/mc0 and that can be 2.2.0, then on next reboot something else. The way to address this, at least in Tru64 world, is to change control port from scsidev@t.b.l to /dev/changers/mcX. In past I believe LGTO support claimed this was not supported even it did work without any issues. You may take same approach here - replace address in control port field with udev given one (eg. /dev/sg9). Can't say if it will work or it needs some additional tweaking, but you can try it at least.

ylam1 · Answer

Hi,Emulex dropped persistent binding from their linux driver from 2.6 kernel. Therefore, we have to rely on udev to get persistent naming. That works great and we can fix the devices path, for example /dev/fc_nst0 to always point to 1st tape drive, /dev/fc_nst2 to the second tape drive and so on. We can also have /dev/fc_autochanger to point to the jukebox.However, when configuring the Jukebox, Legato still use the scsidev@b.t.l to identify the jukebox. If the server reboot, we cannot guarantee that the b.t.l will not change. I believe only persistent binding will solve this issue, not udev.Is there a way to let Legato refer to the jukebox using device path name, instead of using the SCSI target ID? If that's possible, then we use udev to fix a device path name and need not worry about whether the b.t.l change when the server reboot.I know Qlogic still has support for persistent binding for 2.6 kernel. But it's a little troublesome to change the cards

ylam1 · Answer

Yes, We could try it. How do you go about doing it? When I tried to use jbconfig, the list of jukeboxes that are presented as options are addressed in scsidev@t.b.l . How do you use /dev/sg9 to represent the control port? Thanks.

ble1 · Answer

You will first run jbconfig as always - it will use t.b.l. Then, when jukebox configuration is done, go to library properties and there you can edit library control path.

ylam1 · Answer

Hi,I tried changing the library control path but it is listed as a read-only attribute in networker 7.3.2. How do u change that?

ble1 · Answer

I heard somewhere that NMC does that - did you try nsradmin?

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SCSI address of autochanger changes after reboot

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