https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683232#M105545 Please see the attached doc Fri, 03 Sep 2010 23:54:58 GMT donkarnash_1 2010-09-03T23:54:58Z https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683231#M105544 Hi,<BR />I have a ML 570 G3 server. It has one raid controller and two RAID drives. <BR />2 x 36G for OS<BR />4 x 300G for data<BR />I added 4 x 300G HDD and instead of expanding the second RAID group, I clicked to expand the OS RAID group which is 1+0. <BR />I can see the new disks as "unused space" under the 1+0 but I want to remove them.<BR />I do not want to delete the logical drive as I am not sure if that will impact the OS. <BR />I can't take a risk of losing the server. <BR />Is there any way I can remove the new disks from this RAID group ???? Fri, 03 Sep 2010 23:48:13 GMT https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683231#M105544 donkarnash_1 2010-09-03T23:48:13Z https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683232#M105545 Please see the attached doc Fri, 03 Sep 2010 23:54:58 GMT https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683232#M105545 donkarnash_1 2010-09-03T23:54:58Z https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683233#M105546 So you want to go back fron a raid 10 with 6 disks to a raid 1 with 2 disks. right?<BR />I don't think this can be done on the controller. You need to make a backup and reconfigure the raid controller. Sun, 05 Sep 2010 07:05:54 GMT https://community.hpe.com/t5/proliant-servers-ml-dl-sl/undo-array-expansion/m-p/4683233#M105546 wobbe 2010-09-05T07:05:54Z