jbd2/dm-0-8 consuming all I/O

Question

What is jbd2/dm-0-8 and why It is consuming all my I/O usage and causing I/O wait?

Is there anyway to disable this?

Bonnie++ results: http://pastebin.com/iQCWP1qp

$ sudo hdparm -t /dev/sda1

/dev/sda1:
 Timing buffered disk reads: 108 MB in  3.02 seconds =  35.71 MB/sec

Replace the slow and possibly failing disks with faster disks. — Michael Hampton, Jan 02 '13 at 16:11
Thanks, as you mentioned about slow disks I attached my bonnie++ results. Is this kind of a slow disk? — Super Mario, Jan 02 '13 at 18:38
Sheesh, the three year old drive on my desktop is faster than that. — Michael Hampton, Jan 02 '13 at 18:45
Oh, even the hdparm result (added to my question) is bad enough to cause this? — Super Mario, Jan 02 '13 at 18:48
Some details on how I tracked down what `jbd2` was doing when it kept showing up with high % in `iotop` for me : https://serverfault.com/a/801223/181704 — Iwan Aucamp, Sep 05 '16 at 23:51

score 18 · Accepted Answer · answered Jan 02 '13 at 15:42

18

jbd is the "journaling block device". dm-0-08 indicates a device mapped by device mapper. It just indicates that you are doing IO and it is being flushed out to disk properly. It is not by itself a source of IO.

Here is vague advice based on the vagueness of the question: If you need less iowait time, your machine needs to do less work, work more efficiently, or have more io resources to do work with.

answered Jan 02 '13 at 15:42

Yolo Perdiem

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Thanks, I tweaked settings as much as I could but still no change. I also added my bonnie++ results. I hope that might help if it's because slow disks. – Super Mario Jan 02 '13 at 18:40

score 1 · Answer 2 · answered Mar 10 '13 at 21:52

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Was the filesystem recently created? Is there any process named ext4lazyinit?

Then just wait as it inits (prepares, formats) the filesystem.

answered Mar 10 '13 at 21:52

natmaka

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jbd2/dm-0-8 consuming all I/O

2 Answers2