Questions regarding journal replay

[Eric Sandeen]

Ralf Hildebrandt wrote:
> * Eric Sandeen <sandeen at redhat.com>:
> 
>>>> 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.
>>> We had 24GB of reading from the journal device (or 12GB if it's
>>> 512byte blocks). I wonder why?
>> 24GB of reading from the journal device (during that 800s of replay
>> during mount?), and your journal is 128M ... well that's odd.
> 
> After my initial report I removed the journal and created an external
> journal on a 32GB partition. Hoping it would be faster, since
> accoriding to the docs. the journal size is limited to 128MB.
>  
>> You say journal device; is this an external journal?  I didn't think so
>> from your first email, but is it?
> 
> It is now.

...

> Journal block size:       4096
> Journal length:           8488436
> Journal first block:      2
> Journal sequence:         0x0027c611
> Journal start:            2
> Journal number of users:  1
> Journal users:            032613d3-6035-4872-bc0a-11db92feec5e

Ok we might be getting a little off-track here.  Your journal is indeed
32G in size.  But you also saw this with an internal journal, which
should be limited to 128M, and yet you still saw a very long replay, right?

-Eric