Only Dell MD3000i certified drives will work in an MD3000i. The support matrix has a list of supported drive models, but they also then have to have the Dell firmware on them (which you cannot put on there yourself).
Have 8 drives[1] configured as RAID5 + 1 HotSpare. 2 Drives have died. Trying to replace them.  [1]   Physical Disk path redundancy: OK                            It seems Seagate do not make Barracuda's anymore so I bought the equivalent Constellation drives [2]:  [2]  ST1000NM0023 Seagate HDD 3.5 SAS 1TB  When I install a new drive into the MD3000i the 6 original disks all stop and the SAN comes to a grinding halt. When I remove the new drive, they all come good again and the SAN plods along in degraded mode.  Why would inserting a new drive cause the MD3000i to stop working?  If it is a compatibility issue, what are the correct replacement drives?
Replacing failed drives in MD3000i