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I copied my entire music, video and epub library from my external harddrive (NTFS) to a folder in my home directory (ext4)

It was a total of about 100 Gigabytes.

I noticed that over time, the copying rate slowed.

When I did this in reverse prior to installing the new Ubuntu, the rate slowed down to 3.7 Mb per second.

In both situations, after the copying finished, which took a few hours, all functions of the computer were laggy. Windows lagged in loading up. Menus lagged when clicking on them.

The CPU graph in my indicator applet was extremely high. After reboot, it all returned to normal.

Is there some memory leak occurring when writing or reading the hard disk? What's going on here?

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I have seen this behavior but not seen a solution. As far as I can tell it is a kernel bug. The best discussion I know of on this topic, and some possible solutions, is on the fedora forums: but I have not seen a definitive answer. If you google search , this issue comes up on various mailing lists from time to time. I will watch this question with interest to see if anyone has a better answer. – bodhi.zazen Dec 23 '11 at 17:44
Sounds like the external drive is badly fragmented. – psusi Dec 24 '11 at 20:26

It could be for many reasons, but I think that the most probable ones are that the search daemon is indexing your new files, or that nautilus is creating thumbnails for the media files (this is the most common reason for me).

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