Method for maintenance or exchange of encryption function in storage system and storage device

The present invention relates to a method for maintenance or exchange of an encryption function in a storage system using a key management server, in particular, to a method for acquiring key information upon maintenance or exchange of a controller.

A technology exists for encrypting data with an encryption key in an HDD (Hard Disk Drive) inside a storage device of a storage system to improve security (Patent Literature 1). A technology also exists for encrypting data, and upon storing the data over a long period of time, exchanging stored encrypted data on the basis of a new set of encryption standards (Patent Literature 2). Further, a technology exists for generating and managing an encryption key using a key management server different from a storage device in order to improve security in consideration of theft of an HDD or the like (Patent Literature 3).

In the case where the encryption key is generated and managed using the key management server different from the storage device as disclosed in Patent Literature 3, the storage device per se does not generate the key. Therefore, in the case where maintenance or exchange of a controller is performed when a fault is caused in the controller in the storage device, a newly exchanged controller or a spare controller does not have an encryption key, and therefore necessity of deriving a key from the key management server (KMS server) is caused. Thus, a method can be considered for acquiring key information from an exchanged controller by LAN communication to the key management server. However, the key information is acquired after the exchanged controller comes into a ready state, and therefore a problem of taking time for starting up of the exchanged controller is produced.

Patent Literature

PTL 1: JP-A-2005-109641.

PTL 2: JP-A-2005-303981.

PTL 3: JP-A-2010-277427.

Technical Problem

In general, in the case where maintenance or exchange of a controller (CTL) is executed in a storage system in which a function of encrypting stored data is used, maintenance or exchange is conventionally performed by procedures as described below. More specifically, according to a configuration in which a controller (CTL 0 ) before exchange to which I/O module A (a module performing I/O processing on a back-end side) is connected to a KMS server by LAN communication A, and an exchanged controller (CTL 1 ) to which I/O module B is connected to the KMS server by LAN communication B, the following procedures are required in order to complete starting up of CTL 1 :

(1) Securing LAN communication;

(2) Acquiring key information by demanding the information from the KMS server;

(3) Acquiring the key information to start up I/O module B (the key information is required for starting up the I/O module); and

(4) Starting up I/O module B to convert CTL 1 into a ready state.

In (1) described above, LAN communication B cannot perform communication with the KMS server in Patent Literature 3. When an encryption function is not used for stored data, the I/O module can be started up from information in a Flash memory in the controller. However, when the encryption function is used for the stored data, the communication with the KMS server is not ready, and therefore a function for encryption communication cannot be used from the information in the Flash memory. Therefore, the key information cannot be demanded from the KMS server, and thus starting up of CTL cannot be made. Even if an information area of the Flash memory is extended to allow correspondence to the function for encryption communication, a period of time needed from initial start-up to establishment of LAN communication is long, and time is required to reach a Ready state (a state in which I/O can be processed between a host computer and a disk).

Solution to Problems

Controllers in a storage system to which the present invention is applied has a dual configuration, and one is a new controller or a spare controller to be maintained or exchanged, and the other is a controller in a Ready state, and holds key information.

Consequently, according to the present invention, in order to solve the problems described above, the controller (CTL 0 ) in the Ready state spoofs a controller (CTL 1 ) subjected to maintenance or exchange, acquires key information from a key management server, and transfers the information to the controller subjected to maintenance or exchange and to convert the controller into the Ready state. In addition, CEK (Contents Encryption Key)/DEK (Data Encryption Key) being the key information is inherent to each controller.

In the present invention, action of “spoof” as described above is performed as described below.

CTL 0 uses information on authentication and identification of CTL 1 , accesses the key management server (KMS server), and acquires the key information. Next, CTL 0 stores the key information of CTL 1 as acquired from the KMS server in a Flash memory and a Cache memory. Finally, CTL 1 reads the key information from the Flash memory and the Cache memory of CTL 0 , and writes the information in an own Flash memory and an own Cache memory.

Further, CTL 0 deletes the key information of CTL 1 that remains in the own Flash memory and the own Cache memory.

Advantageous Effects of Invention

According to the present invention, a controller in a Ready state spoofs a controller subjected to maintenance or exchange upon maintenance or exchange of an encryption function in a storage system, and acquires key information, and therefore the controller subjected to maintenance or exchange can be quickly started up.

FIG. 1 is a drawing showing a configuration of a storage system in the present Example.

FIG. 2A is a drawing showing an outline of processing of maintenance or exchange of an encryption function.

FIG. 2B is a diagram showing an outline of processing of maintenance or exchange of an encryption function.

FIG. 3 is a diagram showing a flow of processing of maintenance or exchange of an encryption function.

(System Configuration)

A configuration of a storage system in the present Example is shown in FIG. 1 . Disk array device 1 (storage device) that writes and reads data to and from a disk array constituted of a plurality of disks is connected to host computer 2 through SAN (Storage Area Network) 5 , and further connected to SNM (Storage Navigator Modular) 3 and KMS (Key Management Server) 4 through LAN (Local Area Network) 6 . SNM 3 is storage management software for performing integrated management of network infrastructure, and KMS 4 is a server for managing a key for accessing one of the disks.

In disk array device 1 , two lines of controllers, namely, CTL 0 ( 7 ) and CTL 1 ( 8 ) are arranged for HDD (Hard Disk Drive) 9 that configures a disk array constituted of a plurality of disks 17 a to 17 c for storing encrypted data, and the controllers 7 and 8 are connected with HDD 9 by B/E I/O modules 15 a and 15 b each being a back-end module, respectively. B/E I/O modules 15 a and 15 b have an encryption communication device being hardware for controlling transfer of encrypted data between each of controllers 7 and 8 and HDD 9 , and a DEK (Data Encryption Key) list required for data encryption or decryption. Moreover, the controllers 7 and 8 are connected to SAN 5 through host I/O modules 10 a and 10 b , respectively, and connected to LAN 6 through LAN ports 11 a and 11 b , respectively.

Controller CTL 0 ( 7 ) has memory 18 a , and D-CTL 12 a being a microprogram in memory 18 a , and D-CTL 12 a has an encryption function for encrypting or decrypting data, and simultaneously confirms whether HDD 17 performing I/O is RG (RAID Group) or DP (Dynamic Provisioning) Pool for designating encryption. To memory 18 a having D-CTL 12 a , CPU 13 a and Cache memory 14 a are connected, and memory 18 a is further connected to host I/O module 10 a and LAN port 11 a , and B/E I/O module 15 a . D-CTL 12 a in memory 18 a is executed by CPU 13 a . Controller CTL 1 ( 8 ) also has a similar configuration. Two lines of controllers CTL 0 ( 7 ) and CTL 1 ( 8 ) are connected by control line 16 for mutual information exchange or the like.

One of two lines of controllers CTL 0 ( 7 ) and CTL 1 ( 8 ) is a new controller to be maintained or exchanged, or a spare controller, and the other holds the key information and is in a Ready state (a state in which I/O can be processed between a host computer and a disk). Consequently, according to the present Example, controller 7 (CTL 0 ) in the Ready state spoofs controller 8 (CTL 1 ) subjected to maintenance or exchange, acquires the key information from the key management server (KMS 4 ), transfers the information to controller 8 subjected to maintenance or exchange, and converts controller 8 subjected to maintenance or exchange into the Ready state. As a result, maintenance or exchange from controller 7 to controller 8 is completed. The key information acquired by the controller from the key management server (KMS 4 ) is stored in memory 18 a . In addition, when a controller deletes the key information, the controller is in a Halt state (a state in which I/O control is not performed or cannot be performed).

(Processing Flow)

The outline of maintenance or exchange processing of a controller in the present Example is described using FIG. 2A , FIG. 2B and FIG. 3 . A number in a parenthesis shown in FIG. 2A and FIG. 2B corresponds to a number of a processing procedure as described below. Processing (2) and (3) as described below are a part in which CTL 0 spoofs CTL 1 to perform action. A program for executing processing shown in FIG. 3 is stored in controllers 7 and 8 .

(1) CTL 0 performing control of transceiving data between host computer 2 and HDD 9 monitors to detect existence of CTL 1 for maintenance or exchange in disk array device 1 ( 301 ).

(2) CTL 0 accesses a key management server (KMS 4 ) to acquire key information ( 302 ). Methods for acquiring a key have two patterns. Pattern 1: CTL 0 per se recognizes that CTL 1 is inserted, and instructs SNM 3 to acquire key information from CTL 0 . SNM 3 accesses the key management server (KMS 4 ) to acquire key information. Pattern 2: On a console of SNM 3 , a user issues an instruction for acquiring key information.

(3) CTL 0 stores in an own Flash memory and an own Cache memory 14 a the key information of CTL 1 acquired from KMS 4 . A notice of completing storage of the key information is transmitted from CTL 0 to CTL 1 through control line 16 . Although the Flash memory is not shown, controllers 7 and 8 are assumed to have the Flash memory built-in. The Flash memory is used for control of controllers 7 and 8 per se, and Cache memories 14 a and 14 b are used for control of transceiving data between host computer 2 and HDD 9 ( 303 ).

(4) If CTL 1 receives the notice of completing storage of key information from CTL 0 , CTL 1 reads the key information from the Flash memory and the Cache memory 14 a of CTL 0 , and writes the information in the own Flash memory and the own Cache memory 14 b . As a result, CTL 1 comes into a Ready state ( 304 ). A notice of completing read-out of the key information is transmitted from CTL 1 to CTL 0 through control line 16 .

(5) Any information cannot be left in any other system from a security issue, and therefore if CTL 0 receives the notice of completing read-out of the key information from CTL 1 , CTL 0 deletes the key information of CTL 0 that remains in the own Flash memory and the own Cache memory 14 a ( 305 ). As a result, CTL 0 comes into a Halt state. The above-described security issue refers to possibility of occurrence of status described below. More specifically, if any information remains in any other system, the information may be used, for example, for I/O between the host computer and the disk through an unauthorized access route different from an authorized access route.

Even while the above-described maintenance or exchange processing is performed, the control of transceiving data between host computer 2 and HDD 9 is performed as described below. More specifically, the control of transceiving data and above-described maintenance or exchange processing is first performed in CTL 0 (CTL 0 performs the control of transceiving data in behalf of CTL 1 in the meantime) and CTL 1 comes into the Ready state, and then the control of transceiving data is performed in CTL 0 and CTL 1 until the Ready state of CTL 0 is canceled. As a result, the control of transceiving data is not interrupted even during maintenance or exchange processing of the controller. If a controller comes into a Halt state, the controller does not allow I/O processing between the host computer and the disk.

1 : Disk array device, 2 : Host computer, 3 : SNM, 4 : KMS, 5 : SAN, 6 : LAN, 7 , 8 : Controller (CTL), 9 : HDD, 10 : Host I/O module, 11 : LAN port, 12 : D-CTL, 13 : CPU, 14 : Cache memory, 15 : B/E I/O module, 16 : Control line, 17 : Disk, 18 : Memory