[Linux-cluster] RAW Devices performance issue
Shariq Siddiqui
shariq.siddiqui at yahoo.com
Wed Feb 16 10:04:00 UTC 2011
Dear All,
I am going to install Oracle RAC on two Servers, With shared SAN storage
(Servers and Storage is IBM)
OS = RHEL 5u5 x64 bit
And we used multipathing mechanism and created multipathing devices.
i.e. /dev/mapper/mpath1.
Then I created raw device /dev/raw/raw1 of this /dev/mapper/mpath1 Block device
as per pre-reqs for Oracle Cluster.
Every thing looks good, But we faced the performance issue as under...
when we run command :
#dd if=/dev/zero of=/dev/mapper/mpath1 bs=1024 count=1000
the writing rate is approx. 34 MB/s
But If we run command
#dd if=/dev/zero of=/dev/raw/raw1 bs=1024 count=1000
the writing rate is very slow like 253 KB/s
Please advice how to tune the performance.
Best Regards,
Shariq Siddiqui
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