Questions regarding journal replay

[Eric Sandeen]

Ralf Hildebrandt wrote:
> * Ralf Hildebrandt <Ralf.Hildebrandt at charite.de>:
>> * Curtis Doty <Curtis at GreenKey.net>:
>>> Yesterday Ralf Hildebrandt said:
>>>
>>>> The journal replay too quite a while. About 800 seconds.
>>>>
>>> Were there any other background iops on the underlying volume 
>>> devices? Like maybe raid reconstruction?
>> I don't think so. The machine never powered off...
> 
> Again, 2.6.28.7 failed us and now we're encountering another journal
> replay. Taking ages. This sucks.
> 
> Questions:
> 
> How can I find out (during normal operation) HOW MUCH of the
> journal is actually in use?
> 
> How can I resize the journal to be smaller, thus making a journal
> replay faster?
> 

It'd be better to get to the bottom of the problem ... maybe iostat
while it's happening to see if IO is actually happening; run blktrace to
see where IO is going, do a few sysrq-t's to see where threads are at, etc.

Can you find a way to reproduce this at will?

Journal replay should *never* take this long, AFAIK.

-Eric