Abstract:
Described herein are techniques for arranging a plurality of M.2 solid state drive (SSD) modules and flash storage elements into a compact form factor. On a first side of an SSD sled, a plurality of M.2 SSD modules may be communicatively coupled to a port expander. On a second side of the SSD sled, a plurality of flash storage elements (not packaged into M.2 SSD modules) may be present. A plurality of SSD sleds (with the above-described characteristics) may be sized so as to collectively fit into a single hard disk drive (HDD) compatible compartment of a chassis.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a non-provisional patent application of and claims priority to U.S. Provisional Application No. 61/989,452, filed 6 May 2014, which is assigned to the assignee of the present invention and is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to methods for arranging a plurality of solid state drives (SSDs) into a compact form factor, and storage systems in which a plurality of SSDs are arranged into a compact form factor. 
       BACKGROUND 
       [0003]    Most commercially available storage systems generally include those with disk drives (e.g., hard disk drives (HDDs)), those with solid state drives (SSDs) (e.g., flash drives), and those with a combination of the two. Disk drives have the advantage of being lower cost than SSDs. On the other hand, it is typically faster to read data from an SSD than a disk drive. With the advancement of semiconductor technology, SSDs are becoming cheaper to manufacture. Accordingly, in storage systems with a combination of disk drives and SSDs, it is becoming increasingly advantageous to store a larger percentage of data using SSDs. A challenge is how to design a cost effective storage system in which a larger percentage of data is stored using SSDs. 
       SUMMARY OF THE INVENTION 
       [0004]    In one embodiment, disk drives and SSDs are arranged into a commercially available (i.e., off the shelf) chassis. A focus of one embodiment is how to arrange (and electrically interconnect) the maximum number (or a large number) of SSDs into a compact form factor, the form factor dictated by one or more slots of the commercially available chassis. The slot could be a 3.5-inch slot formerly configured to house an HDD. 
         [0005]    In one embodiment of the invention, SSDs that adhere to the M.2 standard, formerly known as the Next Generation Form Factor (NGFF), may be employed, while in other embodiments, SSDs that adhere to other standards could also be employed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  depicts an SSD sled with a plurality of M.2 SSD modules, in accordance with one embodiment. 
           [0007]      FIG. 2  depicts a storage system, in accordance with one embodiment. 
           [0008]      FIG. 3  depicts different views (e.g., top, side views) of one embodiment of an SSD sled with M.2 SSD modules. 
           [0009]      FIGS. 4A-4B  provide further depictions (e.g., top view, bottom view) of one embodiment of an SSD sled with M.2 SSD modules. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0010]      FIG. 1  depicts SSD sled  10 A with a plurality of M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D), in accordance with one embodiment. As depicted in  FIG. 1 , the plurality of M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D) may be communicatively coupled to port expander  14 , which compactly arranges the input/output (I/O) signals of all of the M.2 SSD modules onto a set of I/O ports. Port expander  14 , however, is just one mechanism to compactly arrange the I/O signals, and in another embodiment, port expander  14  may be replaced with a non-volatile memory express (NVMe) peripheral component interconnect express (PCIe) interface. While SSD sled  10 A may contain four M.2 SSD modules in the embodiment depicted in  FIG. 1 , SSD sled  10 A may contain a different number of M.2 SSD modules in other embodiments. See, e.g., the embodiment in  FIGS. 3-4  with five M.2 SSD modules (described below). 
         [0011]      FIG. 2  depicts storage system  20 , in accordance with one embodiment. As depicted in  FIG. 2 , a plurality of SSD sleds ( 10 A,  10 B,  10 C,  10 D), each having M.2 SSD modules, may be communicatively coupled to one or more controllers. For extra reliability, the embodiment depicted in  FIG. 2  includes two controllers ( 22 A,  22 B). In the event that one of the controllers fails, the other controller can take over the operation of the failed controller. Each of the SSD sleds ( 10 A,  10 B,  10 C,  10 D) may be more specifically communicatively coupled to a port expander ( 24 A,  24 B) of each controller. In other embodiments, it is possible to use only a single controller. 
         [0012]    Focusing on controller  22 A for ease of explanation, central processing unit (CPU)  28 A of controller  22 A may be communicatively coupled to port expander  24 A of controller  22 A via host bus adaptor (HBA)  26 A. As is known in the art, data storage and retrieval tasks may be delegated from the CPU to the HBA, freeing up the CPU for other tasks. CPU  28 A may additionally be communicatively coupled to network  32  (e.g., Internet, LAN, WAN, MAN, public network, private network, etc.) via network interface controller (NIC)  30 A. A similar description may apply to controller  22 B. 
         [0013]    Storage system  20  may also contain one or more disk drives, such as hard disk drive (HDD)  34  depicted in  FIG. 2 . One or more disk drives may be communicatively coupled to each controller via the port expander of each controller. 
         [0014]      FIG. 3  depicts different views (e.g., top and side views) of one embodiment of SSD sled  10 A with five M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D,  12 E). Each of the M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D,  12 E) may contain one SATA SSD controller  40  and four NAND flash chips  42 , each flash chip measuring 12×18×1.5 mm. SSD sled  10 A may have dimensions of 101.6 mm wide, 147 mm long and 9 mm high. Each of the M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D,  12 E) may be an 80 mm SATA module. 
         [0015]      FIGS. 4A-4B  provide further depictions (e.g., top and bottom views) of one embodiment of SSD sled  10 A with M.2 SSD modules. In  FIG. 4A , the top view of SSD sled  10 A is depicted without the M.2 modules to better illustrate the other components of SSD sled  10 A. As illustrated, SSD sled  10 A may contain SAS (serial attached small computer system interface) port expander  14  (e.g., PMCS  8053   24  Port SAS Expander with heat sink). Also as illustrated, SSD sled  10 A may contain SAS connector  50  for electrical connection to an SAS bus (not depicted). Also as illustrated, SSD sled  10 A may contain SAS SSD controller  52  (e.g., a PM8304 2×12G SAS SSD Controller). Each M.2 SSD module (not depicted in  FIG. 4A ) may be communicatively coupled to SSD sled  10 A by an M.2 connecter  54  (e.g., a 4.2 mm tall M.2 connector). 
         [0016]    In  FIG. 4B , the bottom view of SSD sled  10 A is depicted. Additional flash chips  56  may be present (i.e., embedded) on the bottom side of SSD sled  10 A, such flash chips being additional to those on the M.2 SSD modules ( 12 A,  12 B,  12 C,  12 D,  12 E). Such embedded SSDs, which could be an SAS or SATA SSD, may support 4 TB of additional capacity. One example SAS SSD is the PMCS 8304 SAS SSD. 
         [0017]    In one embodiment, a base SSD sled configuration may support up to 5 TB, the configuration being formed by up to 5 double-sided M.2 modules (e.g., 1 TB per module). The total supported capacity of an SSD sled may be 8.5 TB instead of 9 TB, since the fifth M.2 module slot may be restricted to a single-sided M.2 module when (a large number of) embedded SSDs are populated on the bottom side of the SSD sled. 
         [0018]    In one embodiment, SSD sled  10 A may conform to the basic dimensional footprint of a 3.5-inch HDD, thus being capable of replacing a 3.5-inch HDD in an existing chassis slot or other receptacle. 
         [0019]    It is to be understood that the above-description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.