Messages in this thread | | | Date | Thu, 24 Nov 2005 15:08:25 +0100 | From | Daniel Nilsson <> | Subject | Re: Performance degradation when using partitions |
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On Tue, Nov 22, 2005 at 10:48:41AM -0500, Bill Davidsen wrote: > Daniel Nilsson wrote: > >While setting up a software RAID-5 array I started looking into the > >performance aspect of using partioned drives versus the whole disks > >for a RAID-5 array. I have an Adaptec 2400a controller which through > >the I2O kernel driver gives me access to 4x 250GB disks (JBOD mode). > > Did you get an answer on this? And does it happen if you use the drives > directly, /dev/hdN or /dev/sdN instead of using I2O? I didn't see an > obvious speed penalty in raw access of drives vs. partitions, but I > lacked the hardware to really match your setup, particularly the I2O use > vs. direct access to /dev/sd[ef].
Bill,
No, I didn't get an answer on this. I've done some more experiments with the drives, but since they are connected to an Adaptec 2400A RAID controller (in JBOD mode) I need to go through some I2O driver in or to see the drives at all. So I never have direct access to these drives as /dev/hdN or /dev/sdN. There are however two different drivers available for this RAID controller, one is the standard I2O driver and the other one is the Adaptec dpt_i2o driver.
The results are the same though whether I use the Linux I2O driver or the Adaptec dpt_i2o, the software raid array is rebuilding at roughly half the speed when the drives are partioned. I don't know what other data to provide in ordet to get any further in the testing.
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