Hello the.mknabster,   After creating array did you give enough time for initialization to complete?   Drive noise could be an indication the drive could fail. I would not use a hard drive that is making noise.  Are they Dell branded drives?   The link you referenced is to a diagnostic. It is now built into the system. Running diagnostics: Boot to  F11 on Dell Splash screen, selecting  Boot Manager -> System Utilities -> Launch Dell Diagnostics.  Note any messages and continue testing.   You can pull a controller log: in Open Manage Server Administrator, expand Storage>select the controller. Click Information/Configuration hyper link at top. Use the ‘Controller Task’ drop down> select Export Log, click Execute and Export on next page. Log will be in Windows folder with file name LSI_####.log     You can also pull a controller log from the LifeCycle Controller:  gather RAID Log via F2   (System Setup) *Have a USB thumb drive FAT32 attached before power up to F2* 1.  Press F2 during the pre-boot options 2.  Select "Device Settings" 3.  Select the RAID Controller 4.  Select "Controller Management" 5.  Select "Save Debug Log"   at the bottom        *You may need to scroll down to view the option 6.  Select "Save Log" after noting the filename that will be saved, and choosing the USB directory from the "Select Directory" option         *the default filename should be:   ttyLog.txt 7.  A message confirms the operation was successful       Look for background processes like initialization, consistency check, patrol read, resync. If the drive is predictive fail it may be busy marking bad blocks. Most resent entries are at the bottom so you may want to work from bottom up to see what is going on.  
I have an odd issue, and i'm trying to figure out if it could be drives going bad, or something working in the background that chooses to use this specific drive. I have one RAID1 set which shows constant activity with associated drive noise, but my other two RAID1 sets are quiet. This is in a T420 with the H710 PERC controller.  Originally when i first built this server, I had a RAID 10 and the noise was there, so i thought maybe there was something wrong so i halved and made it RAID1 to see what would happen, same issue. SO i'm wondering if one or some of the drives i'm using in this array are showing signs of doom. All drives are the exact same, 8TB HGST 7.2K SAS, throughout the server. I did read about another user having a similar issue here: [URL]#M12009, however the FTP site that was linked i could not get to. This "Patrol Read Utility" that is mentioned, is this still a thing 16 years later? What else could be the issue? At this point, i might just take the drives out and try another set, but before i do that, i want to ask the group. Thanks!  
Drive shows constant activity when it shouldn't