Fedora 19 - filesystems slow

[George R Goffe]

Rick,

Thanks for your info. I'll check this out as well. I have used hdparm -B to get and set the APM values... All the drives including the system drive were set to 128. I have set them to 255 now so we'll see what happens.

Actually, the behavior makes me think of a cache that has been emptied... My new activity has to rebuild the cache. Ideally, I'd like to make the cache bigger and have entries written back to the drive(s) BUT remain in cache... A least used algorithm could be used when looking for free space in the cache similar to the one for real memory. Do you know the developers or of a mailing list?


Again, thanks for your response.

George...



________________________________
 From: Rick Stevens <ricks at alldigital.com>
To: George R Goffe <grgoffe at yahoo.com>; Community support for Fedora users <users at lists.fedoraproject.org> 
Sent: Wednesday, July 2, 2014 10:36 AM
Subject: Re: Fedora 19 - filesystems slow
 

On 07/02/2014 12:49 AM, George R Goffe issued this missive:



> Hi,
>
> I have a Fedora 19 system with several large 2-4TB drives attached via USB-SATA docking stations.
>
> I'm seeing a problem whereby a specific filesystem that hasn't been accessed for some time and is REALLY slow to respond to initial requests. ls -alt for example takes a substantial bit of time to respond at first but then response is acceptable after that.
>
> I'm trying to figure out what's happening and why and what I can do about it. It's like the buffers are empty and they need to be filled. Are there kernel tunable parameters that can be changed to avoid this problem?

I can think of two things:

1) The drive was spun down because of inactivity. Try looking at the
man page for "hdparm", specifically the "-B" and "-S" options.

2) Caching. If the filesystem hadn't been accessed in a while, its
contents are probably no longer cached. Don't know if you can do
anything about that.
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