Questions regarding journal replay

Ralf Hildebrandt Ralf.Hildebrandt at
Wed Feb 25 17:40:38 UTC 2009

* Eric Sandeen <sandeen at>:

> >> 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.

# dumpe2fs -h /dev/cciss/c0d0p6
dumpe2fs 1.41.3 (12-Oct-2008)
Filesystem volume name:   journal_device
Last mounted on:          <not available>
Filesystem UUID:          1a7063f5-8965-40f2-9feb-e37d6ac467e9
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      journal_dev
Default mount options:    (none)
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              0
Block count:              8488436
Reserved block count:     0
Free blocks:              0
Free inodes:              0
First block:              0
Block size:               4096
Fragment size:            4096
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         0
Inode blocks per group:   0
Filesystem created:       Thu Feb  5 14:05:36 2009
Last mount time:          n/a
Last write time:          Thu Feb  5 14:15:26 2009
Mount count:              0
Maximum mount count:      30
Last checked:             Thu Feb  5 14:05:36 2009
Check interval:           15552000 (6 months)
Next check after:         Tue Aug  4 15:05:36 2009
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:		            256
Required extra isize:     28
Desired extra isize:      28
Default directory hash:   half_md4
Directory Hash Seed:      fddb247a-97df-4582-bfcd-816ef8c17ab2

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

Ralf Hildebrandt                                Ralf.Hildebrandt at
Charite - Universitätsmedizin Berlin            Tel.  +49 (0)30-450 570-155
Geschäftsbereich IT | Abt. Netzwerk             Fax.  +49 (0)30-450 570-962
Hindenburgdamm 30 | 12200 Berlin

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