Greetings, My organization recently upgraded to RHEL 5.4, which included an updated mdadm RPM (mdadm-2.6.9-2.el5). Included in the new RPM was a cron job that does a weekly consistency check on the available RAID arrays. After the checks completed, I found that most of our systems had a mismatch_cnt that was != 0. I've seen mention of this problem on the mailing list before when swap is being used on the problem array, which is not the case for us. Out of about 50 systems I checked, I found roughly 30 arrays that had a mismatch_cnt != 0. The systems I found with problems vary in kernel versions (2.6.18 - 2.6.29) and have different types of media attached (SATA, SCSI, SAS, SAN). In the case of SAN volumes, we have a RAID 1 mirror across 2 SAN volumes. The SAN volumes sit on-top of a linux RAID 5 array on the targets. I did a consistency check on the RAID 5 arrays and did not find any problems (mismatch_cnt = 0). The most popular mismatch_cnt values are 128 and 256. The worst I found was 21504 and 7168. I find it interesting that all are divisible by 128. So, is there anyway to get an output on which blocks do not match? I'd like to see how they are different, if at all. Regards, Bryan
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