High IOWait issue
 

Hello,

I've been having a problem in Ubuntu 9.10 recently where starting about 2 minutes after startup my computer slows down and becomes unresponsive. I believe the problem is associated with a high IOWait because I have the system monitor applet on my Gnome Panel and it displays 100% IOWait every time my system starts to slow down.

I have tried booting into other kernel version and the problem persists.

I don't really know what IOWait is or how to diagnose this problem further. I've looked around online and it seems like you have to find a specific process that is causing the IOWait, but I don't understand how to go about doing that.

Can anyone help me or relate their experiences with this issue?

Thanks in advance for your replies.

IOWait is typically caused by something that is creating lots of internal I/O throughput (e.g. HDD activity). Is your hard drive chattering away while this is happening? If so, how much memory do you have installed in your machine? It could be that your system is paging, or using a section of hard disk space as RAM, which is very slow (and I/O intensive).

My hard drive is not chattering away, but it never really does (I think its rather silent). I don't think its due to paging since my system has 2 GB of RAM and RAM usage, as indicated by System Monitor, is rather low. Could the problem be caused by a specific process and is there a way to find out which process is the culprit?

Thanks so much for your response!

use iotop - it's in the Karmic repositories. Looks like top - but for I/O.

I ran a hard disk diagnostic program from my laptop's BIOS and I got the following error:

Error Code 0000: Read Verification Failed

Then when I booted into Ubuntu I found a notification icon that says my disk has many bad sectors. When I open up the Palimpsest Disk Utility, they suggest I back up all data and replace the disk. Is this my only option?

The specific attribute that has a warning is the Current Pending Sector Count. The description is:

Number of sectors waiting to be remapped. If the sector waiting to be remapped is subsequently written or read successfully, this value is decreased and the sector is not remapped. Read errors on the sector will not remap the sector. It will only be remapped on a failed write attempt.

Under the "Value" column in Palimpsest it says:

Normalized: 100
Worst: 100
Threshold: 0
Value: 72 sectors

I would say go ahead and replace it. Bad sectors aren't something you want to deal with, unless you're willing to risk losing data.

I've had the same problem before. The way I preserved the OS/data was to get a new hard disk of the same capacity as the original (I got one that was the same make and model, and free of charge because it was still under warranty), and use Clonezilla to make an exact bit-by-bit duplicate of the disk. It worked great for me; I attached both HDDs to the comp and just did a device-device transfer. Not sure how one would do it on a laptop, though...maybe create an image file on an external drive and restore it on the new primary drive from that.

Hope this helps ;)

Thanks for the advice. I think that's what I'm going to do. Clonezilla looks great!