topic Legacy Vs New device tree in Operating System - HP-UX

Legacy Vs New device tree

Srimalik — Fri, 05 Jun 2009 14:02:08 GMT

Hi,

Is it expected(possible) that on an 11.31 machine for some disks only the new device nodes(/dev/disk) are created and there will be no nodes in the old device tree(/dev/dsk)?

I have a machine with some external disks connected which have entries only in the new device tree. From the documents available I could not find anything which explains this.

The disks are missing from ioscan -fnC
ioscan -fNC shows the disks.
sam shows the disks but the hardware path entry is empty.
ioscan -m dsf also does not show the mapping of missing devices.

Thanks
Sri

Re: Legacy Vs New device tree

Steven E. Protter — Fri, 05 Jun 2009 14:17:27 GMT

Shalom,

Clearly its possible because you see it.

At this point, I'd run some dd tests to see if everything you think you see is real.

SEP

Re: Legacy Vs New device tree

Duncan Edmonstone — Fri, 05 Jun 2009 14:28:17 GMT

It's possible in 2 circumstances that I can think of:

i) Legacy mode addresshas ben turned off. Check with "insf -Lv"

ii) There are a large number of disks (or a large number of disk changes) on the system and the maximum number of controllers for legacy device naming has been exceeded (no more that 255 ext_bus entries). You can check this with "ioscan -fuC ext_bus" - if the instance numbers are anywhere need 255 you probably hit this limit (bear in mind you can't see entries for devices that have been removed)

HTH

Duncan

Re: Legacy Vs New device tree

Srimalik — Fri, 05 Jun 2009 17:28:49 GMT

>Clearly its possible because you see it.
I also wrote expected :-)

>At this point, I'd run some dd tests to see if everything you think you see is real.

scsci enquiry works for the device, diskinfo works, dd also works.

>i) Legacy mode addresshas ben turned off. Check with "insf -Lv"
Its on
# insf -Lv
insf: Legacy mode is enabled
#

This machine has 12 disks 8 of which show up fine in the legacy tree just 4 of them are missing.

>ii) There are a large number of disks (or a large number of disk changes) on the system and the maximum number of controllers for legacy device naming has been exceeded (no more that 255 ext_bus entries). You can check this with "ioscan -fuC ext_bus" - if the instance numbers are anywhere need 255 you probably hit this limit (bear in mind you can't see entries for devices that have been removed)

This is not the cases here, i am not hitting this limit.

I tried recreating these entries with insf but not success. :-(, reboots also have no effect.

Re: Legacy Vs New device tree

Duncan Edmonstone — Fri, 05 Jun 2009 18:39:10 GMT

So the next question is - what sort of disks are you having problems with? Sometimes having the wrong settings on disk arrays can cause this sort of thing...

HTH

Duncan

Re: Legacy Vs New device tree

Srimalik — Sat, 09 Oct 2010 04:44:04 GMT

This was due to the LUN addressing mode which was assigning a LUN ID greater than 7 and those LUNS were not visible.