The K4D64 BOSS-S1 from Dell is a simple RAID solution card designed specifically for booting a server's operating system. The card supports up to two 6 Gbps M.2 SATA drives. The BOSS-S1 adapter card has an x8 connector using PCIe gen 2.0 x2 lanes, available only in the low-profile and full-height form factors. BOSS-S1 card allows you to create only one virtual disk from the available physical disks. Specifying the size of a virtual disk is not supported.
The Dell PowerEdge Boot Optimized Storage Solution (BOSS) S1 provides a highly reliable, and cost-effective solution for segregating operating system boot drives from data on server-internal storage. Many customers, particularly those in the HyperConverged Infrastructure (HCI) arena and those implementing Software Defined Storage (SDS), prefer to separate their operating system drives from data drives, and require hardware RAID mirroring (RAID1) for their OS drives. The main motivation for this is to create a server configuration optimized for application data. Providing a separate, redundant disk solution for the operating system enables a more robust, optimized compute platform.
PowerEdge Engineering developed a simple, cost-effective way of meeting this customer's need. The Boot Optimized Storage Solution uses one or two M.2 SATA devices instead of 2.5" SSD drives to house the OS and utilizes a two-port SATA Hardware RAID controller chip to provide Hardware RAID 1 and Pass-Through capabilities. The M.2 devices offer the same performance as 2.5" SSD drives, and by consolidating the SSDs and controller chip on a single PCIe adapter card, the solution frees up an additional drive slot for data needs.
Substitute PN:
 7HYY4
 JV70F
 72WKY
 M7W47 
Compatible With:
 PowerEdge C4140
 PowerEdge C6525
 PowerEdge R240
 PowerEdge R340
 PowerEdge R440
 PowerEdge R540
 PowerEdge R640
 PowerEdge R740
 PowerEdge R740xd
 PowerEdge R940
 PowerEdge R6415
 PowerEdge R7415
 PowerEdge R7425
 PowerEdge R6515
 PowerEdge R6525
 PowerEdge R7515
 PowerEdge R7525
 PowerEdge T140
 PowerEdge T340
 PowerEdge T440
 PowerEdge T640