I just tried and miss-match count is zero. Interesting, is XOR engine doing something wrong ? . Then I ran a test where I raw-write the file to /dev/md0. Then did the raw-read for the same size. In this case XOR matched as expected. Then I failed a drive using "mdadm -f /dev/md0 /dev/sda". Then I read the same size data again from /dev/md0. And checksum matches too. What is this mean XOR engine is doing right thing. But "chec/repair" test is not functioning properly with XOR-engine ? Or is this something to do with how the buffers are handled ? may they are cached ? -Marri -----Original Message----- From: goswin-v-b@xxxxxx [mailto:goswin-v-b@xxxxxx] Sent: Thursday, January 28, 2010 10:24 AM To: Tirumala Reddy Marri Cc: linux-raid@xxxxxxxxxxxxxxx Subject: Re: Why does one get mismatches? "Tirumala Reddy Marri" <tmarri@xxxxxxxx> writes: > I have noticed that if I zero the /dev/md0 using "dd if=/dev/zero > of=/dev/md0 bs=4k count=64k". Then I run the "echo check > > /sys/block/md0/md/sync_action", no mismatch_cnt reported. If I use > "if=/some/file" then I see miss match count to set to huge number. > > I am testing with small RAID-5 size for quick testing. How a reliable > is this test ? I am using HW accelerated XOR engine for RAID-5. Have you tried without? Maybe the XOR engine creates garbage. MfG Goswin -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
