[linux-lvm] Re: more info on the hang with 2.6.15-rc5

[Matthew Gillen]

Sebastian Kuzminsky wrote:
> Bill Davidsen <davidsen at tmr.com> wrote:
> 
>>Sebastian Kuzminsky wrote:
>>
>>
>>>Now it works, but I dont trust it one bit.
>>>
>>>I had been seeing almost immediate, perfectly repeatable hard lockups
>>>in 2.6.15-rc5 and 2.6.15-rc5-mm3, when using sata_mv, RAID, and LVM
>>>together.  Nothing in the syslog or on the console, and the system is
>>>totally unresponsive to the keyboard & network.
>>>
>>>My hardware setup is: four Seagate Barracuda 500 GB disks, on a Marvell
>>>MV88SX6081 8-port SATA-II PCI-X controller, on a PCI-X bus (64/66).
>>>
>>>The disks work great when accessed directly.  They work great when used
>>>as four PVs for LVM, and when assembled into a 4-disk RAID-6.
>>>
>>>But when I make a RAID-6 array out of them, and use the array as a PV,
>>>the system would hang completely, within seconds.  (This is with LVM
>>>2.02.01, libdevicemapper 1.02.02, and dm-driver 4.5.0.)
>>>
>>>I turned on all the debugging options in the kernel config hoping to get
>>>some insight, but this "debug" kernel doesnt crash.  It's running fine,
>>>and I'm pounding on it.  A timing problem in the interaction between
>>>LVM and RAID?  Some kind of wierd heisenbug....
>>>
>>>
>>>I'd be happy to do any debugging tests people suggest.
>>>
>>>
>>> 
>>>
>>
>>I've been waiting for more info on this, did it get fixed? 2.6.15?
> 
> 
> Still broken in 2.6.15.  With all the debugging options OFF in the config,
> the system stayed up < 24 hours under load, then a hard lockup like
> before: nothing on the console, magic sysrq doesnt work, no caps-lock,
> no ping.  Note that this is different from before: it actually ran a
> little bit before locking up, rather than locking up within seconds like
> it did with 2.6.15-rc5.
> 
> With all the debugging options ON, it's stayed up for 3+ days now (and
> still running) with no problems.
> 
> 
> Any suggestions for how to debug this are welcome!  ;-)

I couldn't quite tell from your description: are you getting the lockup
when you try to mount a filesystem that uses the RAID+LVM as a device?
Or do you get errors when doing LVM-level stuff (ie no filesystem can
even be put on the device)?
In the case of the former, what filesystem are you using?

--Matt