Hello, Let's suppose I am seeing slow write performance on a RAID5 or RAID6, and I am suspecting that it's because of one of its devices operating slower than others (maybe a soft-failing or just low-performing hard drive, in case with non-identical member drives). Nothing in dmesg, no timeouts or ATA errors or anything like that. How would I go about diagnosing which device that is (if any) is slowing down the array, aside from performance-testing each individual device (which seems rather difficult if it's only slow on writes, not reads). In 'top' there's of course high iowait, 50-70% all the time during writes. But is that broken down somewhere to show which particular block device is being the most 'waited for'? -- With respect, Roman
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