Re: Newbie - Identifying IO bottlenick with systat. How to make sense of these numbers?

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From: Robert
Date: Monday, March 22, 2010 - 1:44 pm

Andres Salazar wrote:

You can test the performance with "dd":

a) raw
write: dd if=/dev/zero of=/dev/rsd0z bs=1024k count=1000
read: dd if=/dev/rsd0z of=/dev/null bs=1024k count=1000
Be aware that the write command will of course overwrite the whole 
partition/data (e.g. sd0z).

b) file system
Mount the filesystem using whatever options you want to include in the 
test, eg. "mount -o noatime,softdep /dev/sd0z /mnt/test"
write: dd if=/dev/zero of=/mnt/test/empty.file bs=1024k count=1000
read: dd if=/mnt/test/empty.file of=/dev/null bs=1024k count=1000

You need/should run "sync" between any write and read test to complete 
all writing operations.

Generally you might want to search the archives 
(http://marc.info/?l=openbsd-misc), there have been a lot of postings 
about any kind of performance issues.


kind regards,
Robert
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Re: Newbie - Identifying IO bottlenick with systat. How to ..., Robert, (Mon Mar 22, 1:44 pm)