You could convert the ext4 file system to btrfs, add the second drive to the btrfs and then convert to raid 1. Jason <div class="gmail_quote">On Aug 3, 2014 9:21 AM, "Clay Dowling" <<a href="mailto:clay@lazarusid.com">clay@lazarusid.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> <div style="font-size:10pt">That will indeed delete all of your files. Take a backup before fiddling with filesystem options.------ Original message------ From: Chick TowerDate: Sat, Aug 2, 2014 11:44 PMTo: <a href="mailto:linux-user@egr.msu.edu" target="_blank">linux-user@egr.msu.edu</a>; Subject:[GLLUG] Establishing Software RAID1 <pre>I've found on-line instructions for setting up RAID1 with two disk drives on a system already running Linux. After using mdadm to create a RAID set on two partitions already formatted ext3, they then say to issue the command mkfs.ext3 /dev/md0 Won't that erase anything already on the two drive partitions that make up md0? Also, does anyone know where to buy SATA cables cheaply? I think I need to replace one that I suspect is faulty. -- Chick _______________________________________________ linux-user mailing list <a href="mailto:linux-user@egr.msu.edu" target="_blank">linux-user@egr.msu.edu</a> <a href="http://mailman.egr.msu.edu/mailman/listinfo/linux-user" target="_blank">http://mailman.egr.msu.edu/mailman/listinfo/linux-user</a> </pre></div> _______________________________________________ linux-user mailing list <a href="mailto:linux-user@egr.msu.edu">linux-user@egr.msu.edu</a> <a href="http://mailman.egr.msu.edu/mailman/listinfo/linux-user" target="_blank">http://mailman.egr.msu.edu/mailman/listinfo/linux-user</a> </blockquote></div>