On Nov 10, 2014, at 11:26 PM, George R Goffe <grgoffe@yahoo.com> wrote:

Hi,

I have some large ext4 filesystems with large numbers of files in them and performance really sucks. After inactivity, a simple ls takes minutes to complete. I'm pretty sure the drive is now powering itself down due to this inactivity.

Are there tuning parameters that I could alter that would keep more of the filesystem meta data in memory? It looks like the data slowly migrates back to disk and as a result, takes minutes to fill back up enough to respond.

Regards and THANKS for your help and your time,

It could be fragmentation or it could be non-optimal directory structure. When was the last fsck -f performed? It will optimize directories as needed, but can be forced with -D but I’d ask on the ext4 list before using it. And e4defrag -c can be used to get a fragmentation score, which can be run on a file or a directory.