kern/104406: [ufs] Processes get stuck in "ufs" stateunderpersistent CPU load

[Oleg Derevenetz]

>> > > After my break to debugger using Ctrl+Alt+Esc sequence and entering a
>> > > "panic" command kernel does not wrote a kernel dump but seems to 
>> > > hang.
>> Can
>> > > anyone describe how to obtain a kernel dump in this situation, or at
>> least
>> > > say - which output of show commands need in first place to debug this 
>> > > ?
>> > > Output of all suggested commands is huge and I afraid of making 
>> > > mistake
>> > > when carrying this output from screen to list of paper and back :-)
>> >
>> > Oleg, one thing you can do to make this less painful is to
>> > run your machine's console over serial port.
>> >
>> > First get a crossover serial cable, make sure it works from one
>> > box to another, it should be easy to run "tip com1" on both
>> > boxes to ensure that it works.
>> >
>> > Then you just need to add console=comconsole to /boot/loader.conf
>> > and your box's console should come over serial.
>> >
>> > Then on the machine watching the console, you can just do this:
>> >
>> > % script
>> > Script started, output file is typescript
>> > % tip com1
>> > ...do ddb stuff now...
>> > ...stop tip
>> > % exit
>> >
>> > now you should have everything logged into a file called "typescript"
>> > should save you a big headache.
>>
>> Thanks, I'll try it in the monday morning.
>>
>> > As far as getting a dump from ddb, try this:
>> >
>> > ddb> call doadump
>> >
>> > I'm completely at a loss why this isn't a base ddb command "dump"
>> > but whatever... :)
>>
>> Unfortunately, this doesn't work too. I called duty personnel in this
>> datacenter and asked them to do this, and person on duty tells me that 
>> after
>> he enters this command something like that arrives on monitor:
>>
>> db> call doadump
>> Dumping 3072 MB
>>
>> Dump aborted error I/O
>> Dump failed. (Error 5)
>
> Hmnmm, that seems like you might be having a hardware problem,

It is possible, but unlikely:

1. I have simular symptoms on another AMD64 machine with 6.2 (uname -a from 
this machine listed in PR kern/104406 in my followup at Wed, 7 Mar 2007 
05:10:59 +0300), but they are rare and this machine is in production, so I 
can't make experiments with it;
2. All these hardware successfully works earlier with FreeBSD 4.6.

> what disk device do you have?

Dumpdev is swap partition on da0 (single physical disk) that connected to 
Mylex AcceleRAID 170 RAID controller. The problem arrives when I copy large 
amount of files from FTP to another disk (da1) that is connected to the same 
RAID controller.

> Have you also enabled kernel dumps via /etc/rc.conf:dumpdev=
> ?

Yes, I have dumpdev="AUTO" in rc.conf and swap device (4G) listed in 
/etc/fstab.

--
Oleg Derevenetz <oleg at vsi.ru> OOD3-RIPE
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