[Linux-cluster] FS Block Size Limit

Mike Fedyk mfedyk at matchmail.com
Fri Sep 3 19:15:30 UTC 2004


Ken Preslan wrote:

>On Fri, Sep 03, 2004 at 12:40:49PM +0200, Richard Mayhew wrote:
>  
>
>>I tried to format our 4 GFS partitions with a block size of 8192 (twice
>>the default) to correspond with the default raw block size on the SAN's
>>LUN's to do some performace comparisons with no success. Any block size
>>1024*X < 4096 worked with no problems, anything larger than 4096 came
>>back with an error when trying to mount the file system.
>>
>>Any idea as to why there is a limit set to 4096?
>>    
>>
>
>Linux filesystems can't have block sizes greater than the machine's
>page size.  For x86 and x86_64 that's 4096 bytes.  I've seen 16k pages
>on a IA64 box, so you can go larger there.
>
I remember some threads on LKML about larger page sizes on x86.

Not sure on the current status, but you'll want to look into "page cluster".

Mike




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