[zfs-discuss] ARC cache and ls query

[Henrik Johansson]

Hello John,

On Oct 30, 2009, at 9:03 PM, John wrote:

> Hi,
>
> On an idle server, when I do a recursive '/usr/bin/ls' on a folder,  
> I see a lot of disk activity. This makes sense because the results  
> (metadata/data) may not have been cached.
> When I do a second "ls" on the same folder right after the first one  
> finished, I do see disk activity again.
>
> Can someone explain why the results are not cached in ARC?

You would have disk access again unless you have turned set atime to  
off for that filesystem. I did posted something similar a few days  
back and write a summary of the ARC-part of my findings: http://sparcv9.blogspot.com/2009/10/curious-case-of-strange-arc.html

Here is the whole thread: http://opensolaris.org/jive/thread.jspa?messageID=430385

If that does not explain it you should probably provide some more  
data, how many files, some ARC statistics etc.

Regards
Henrik

Henrik
http://sparcv9.blogspot.com

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