2011/4/30 Jussi Hirvi <listmember at greenspot.fi>: > I am sure this is really simple. > > I have a setup of 2 disks (sda, sdb) which are outwardly identical, and > are mirrors of each other. Together they form 3 raid1 devices. Both > disks can boot. > > Now sda has bad sectors, and I should replace it. But which one of the > physical disks is sda?? take look at serial number using smartctl http://www.techrepublic.com/blog/opensource/using-smartctl-to-get-smart-status-information-on-your-hard-drives/1389 -- Eero