TSM storage agent on RHEL 6 troubles

[philburg2]

Got a brand new RHEL 6 box, qlogic HBAs, DD890 VTL setup and zoned with LTO1 tapes, and the lin_tape IBM driver setup.

lin_tape - 1.67
qla2xxx - 8.03.01.05.06.0-k8
RHEL - 2.6.32-71.18.1.el6.x86_64

We can see the drives, pull them into the IBM config, but everything disappears on reboot. The IBM directions don't mention anything about any required modprobe or initrd commands, so what's going on?

[gimlet]

What do you have in /etc/modprobe.conf?

[philburg2]

Strangley enough, the lin_tape doesn't use modprobe (from what I can tell) to get itself running. It uses a daemon called lin_taped to start itself like a normal program out of /etc/rc2.d. It's funny how IBM set all this up with RPMs to seemingly simplify it, but it makes it harder to troubleshoot in the end.

[moon-buddy]

Strangley enough, the lin_tape doesn't use modprobe (from what I can tell) to get itself running. It uses a daemon called lin_taped to start itself like a normal program out of /etc/rc2.d. It's funny how IBM set all this up with RPMs to seemingly simplify it, but it makes it harder to troubleshoot in the end.

Yes - the DD880/890 uses lin_tape drivers as its mode of emulating LTO tape.

We are running TSM 6.1.5.10 (also on RHEL) and we need to get an eFix from IBM (differently complied dsmserv binary) in order to work around some of the lin_tape issues.

[philburg2]

Well I have heard of such things, the problem really is I can't keep the tapes known to the OS persistently, so TSM isn't in the equation just yet. I think I was gonna try the 5.5.5-2 storageagent with RHEL 6 and our TSM 5.5.5.2 backend, but one thing at a time. Like I said, it seems to work fine on RHEL5. Last advice I got was IBM would likely be far more helpful than redhat support in pursuing this.

[moon-buddy]

Our Red Hat is at 5.4.

I have heard 'horror' stories on Red Hat 6 with the non-persistent device assignments but had not looked into it that deep.

I doubt if IBM can be much of any help on this.

[gimlet]

Philburg,

Looking at this from RHEL5...I haven't had the "pleasure" of dealing with RHEL6 device assignments...

Are all the kernel modules loading (qla2xxx, lin_tape)? The qla drivers may need configuration in /etc/modprobe.conf

# /sbin/lsmod|grep qla
# /sbin/lsmod |grep lin_tape

When you say that you can see the drives, but they disappear on reboot, what steps are you doing to get them working in the first place?

Thanks,

Tom

[philburg2]

echo "scsi add-single-device <CARD> 0 <MASK> <LUN>" > /proc/scsi/scsi

[philburg2]

Yeah, by pleasure you mean how upon reboot my Fiber adapter order flipped so it went from card 1,3 to 0,2... all because Linux can't properly enumerate the bus it seems. Last few times have been consistent however, so I don't believe that's the root of the issue. It's quite possible something needs to be setup in /etc/modprobe.d/modprobe.conf to 'anchor' the devices.

[gimlet]

Yeah, I don't think that should persist after a reboot.

Redhat's docs for 6 point to this for persistent naming, although it's for RHEL 5:

https://access.redhat.com/knowledge/solutions/7318

[philburg2]

Solid find, although it doesn't work with RHEL6 quite right, but it's a step in the right direction.

I was able to echo in a tape drive, and it showed up in /sys/class/lin_tape as IBMtape0, as well as in /proc/scsi/IBMtape. So perhaps the answer is finding a way to 'register' a position in the OS/kernel for these devices.

Thanks Captain Brannigan

[gimlet]

This IBM Technote might be useful, although it doesn't say which distros or kernel versions it applies to:

http://www-01.ibm.com/support/docvie...id=swg21459487

FWIW, running it against my RHEL5.1 system with a 2-drive library gives no serial numbers.

[philburg2]

You are nailing these articles... I never found half this stuff on a half dozen attempts. I'll post later if it bears any fruit.

Thx

[philburg2]

https://access.redhat.com/knowledge/solutions/45626 is the RHEL6 article, but it doesn't actually work in my case.
I get nothing returned from the command.

[root@lx-pmsgrdm-p03p scsi]# more IBMtape
lin_tape version: 1.67.0
lin_tape major number: 247
Attached Tape Devices:
Number model SN HBA SCSI FO Path
0 ULTRIUM-TD1 5402870001 qla2xxx 1:0:0:1 NA

[root@lx-pmsgrdm-p03p dev]# ls -l /dev/IBMtape0
crw-rw-rw- 1 root root 247, 0 Apr 18 14:34 /dev/IBMtape0

[root@lx-pmsgrdm-p03p scsi]# scsi_id --whitelisted --replace-whitespace --device=/dev/IBMtape0
*nothing returned*

[gimlet]

Did you try using the -g option? From the RHEL5 manpage for scsi_id(:


-g Treat the device as white listed. The -g option must be speci-
fied on the command line or in the scsi_id configuration file
for scsi_id to generate any output.

[philburg2]

Finally solved the problem. As far as I can tell, with VTL configurations + linux, you need to apply the library changers in addition to the tape drives. This seems to allow the drives to be properly addressed by the driver.

Basically I rebuild the VTL zoning definitions and used the latest lin_tape driver and it started working consistently.