Dell PowerEdge (PE) servers can expand system storage capacity with direct-attach PowerVault (PV) disk arrays. Compatibility of various PowerEdge RAID Controllers (PERC), PE servers, and PV disk arrays are listed on the Dell site under the “External Storage” tab.
The current standard disk arrays (storage enclosures) are the 2U MD1200 and 2U MD1220 models. The main difference between these is the number and size of disks supported. The MD1200 supports 12 3.5in size SAS drives. The MD1220 supports 24 2.5in size SAS drives.
Use the OpenManage Server Administrator (OMSA) tool from Dell to manage your RAID within Windows.
When you run out of storage expansion options on the server itself, these provide a cost effective way to get more disk space with the dedicated performance you would expect from directly connected SAS volumes.
Good luck with your storage solutions!