lkml.org 
[lkml]   [2005]   [Nov]   [22]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
    /
    DateTue, 22 Nov 2005 09:29:47 +0100
    SubjectRe: Poor Software RAID-0 performance with 2.6.14.2
    FromHelge Hafting <>
    On Mon, Nov 21, 2005 at 09:31:14PM +0100, Lars Roland wrote:
    > I have created a stripe across two 500Gb disks located on separate IDE
    > channels using:
    > 
    > mdadm -Cv /dev/md0 -c32 -n2 -l0 /dev/hdb /dev/hdd
    > 
    > the performance is awful on both kernel 2.6.12.5 and 2.6.14.2 (even
    > with hdparm and blockdev tuning), both bonnie++ and hdparm (included
    > below) shows a single disk operating faster than the stripe:
    > 
    To rule out hardware problems (harware not as parallel as you might think):
    
    Try running the performance test (bonnie++ or hdparm)
    on both /dev/hdb and /dev/hdd at the same time. 
    
    Two hdparms on different disks should not take longer time than one,
    unless you have bad hardware.
    
    One bonnie with size x MB takes y minutes to run.
    Two bonnies, each of size x/2 MB should take between
    y/2 an y minutes to run. If they need more, then something
    is wrong again, explaining bad RAID performance.
    
    Helge Hafting
    
    
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at  http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at  http://www.tux.org/lkml/
    
    
    \
     
     \ /
      Last update: 2005-11-22 09:29    [from the cache]
    ©2003-2008