US20010011331A1 - Controlling shared disk data in a duplexed computer unit - Google Patents
Controlling shared disk data in a duplexed computer unit Download PDFInfo
- Publication number
- US20010011331A1 US20010011331A1 US09/043,195 US4319598A US2001011331A1 US 20010011331 A1 US20010011331 A1 US 20010011331A1 US 4319598 A US4319598 A US 4319598A US 2001011331 A1 US2001011331 A1 US 2001011331A1
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- US
- United States
- Prior art keywords
- disk drive
- computer
- disk
- data
- computers
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F12/00—Accessing, addressing or allocating within memory systems or architectures
- G06F12/02—Addressing or allocation; Relocation
- G06F12/08—Addressing or allocation; Relocation in hierarchically structured memory systems, e.g. virtual memory systems
- G06F12/0802—Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches
- G06F12/0806—Multiuser, multiprocessor or multiprocessing cache systems
- G06F12/0815—Cache consistency protocols
- G06F12/0831—Cache consistency protocols using a bus scheme, e.g. with bus monitoring or watching means
- G06F12/0833—Cache consistency protocols using a bus scheme, e.g. with bus monitoring or watching means in combination with broadcast means (e.g. for invalidation or updating)
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F11/00—Error detection; Error correction; Monitoring
- G06F11/07—Responding to the occurrence of a fault, e.g. fault tolerance
- G06F11/16—Error detection or correction of the data by redundancy in hardware
- G06F11/20—Error detection or correction of the data by redundancy in hardware using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F12/00—Accessing, addressing or allocating within memory systems or architectures
- G06F12/02—Addressing or allocation; Relocation
- G06F12/08—Addressing or allocation; Relocation in hierarchically structured memory systems, e.g. virtual memory systems
- G06F12/0802—Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches
- G06F12/0866—Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches for peripheral storage systems, e.g. disk cache
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2212/00—Indexing scheme relating to accessing, addressing or allocation within memory systems or architectures
- G06F2212/31—Providing disk cache in a specific location of a storage system
- G06F2212/311—In host system
Definitions
- the invention relates to duplexed computer systems and especially to an arrangement with which two computer units can control data on the same disk drive.
- duplexed computers are usually arranged in such a way that only one (e.g. 10 ) of the computers 10 and 20 uses a disk drive 14 and/or a disk drive 24 .
- the other computer in this case 20 ) is then in reserve or faulty.
- a first disk drive bus 15 connects both computer units and the first disk drive 14 .
- a second disk drive bus 25 connects both computer units and the second disk drive 24 .
- FIG. 1 shows an embodiment where each computer unit 10 and 20 comprises two disk drive controllers 13 a and 13 b , and 23 a and 23 b , respectively.
- each computer unit 10 and 20 might comprise one disk drive controller having two separate interfaces to the disk drive buses 15 and 25 .
- the disk drive buses 15 and 25 may be for example SCSI (Small Computer Systems Interface) buses and the disk drives 14 and 24 may correspondingly be disk drives with SCSI interfaces.
- FIG. 1 also shows a bidirectional message bus 30 connecting the computers 10 and 20 . Via the message bus 30 the commuters 10 and 20 interchange maintenance messages, for example they inquire about each other's condition etc.
- FIG. 1 The system of FIG. 1 is shown with two disk drives 14 and 24 since in duplexed systems the disk drives are usually also duplexed.
- the disk drive buses have also been duplexed.
- the disk drives 14 and 24 could also be connected to a common disk drive bus 15 or 25 .
- the invention relates to controlling disk drives regardless of any other disk drives that the system may comprise. The number of disk drives and disk drive buses is therefore not essential to the invention.
- Caching the data of the disk drive 14 in the main memory 12 of one computer 10 constitutes technology that is known to a person skilled in the art.
- the caching is based on the empirical observation that when a disk task is performed to some part of the disk drive 14 , it is likely that another disk task is performed relatively soon to the same part. Therefore it is preferable to store in the main memory 12 the data corresponding to some of the most recently used areas of the disk drive 14 .
- a certain area is usually reserved from the main memory 12 .
- the disk drive controllers 13 a and 13 b may contain a separate cache memory.
- a problem occurs with the use of duplexed computers each of which is to be provided with the possibility of using at least one disk drive 14 and 24 while the operation is expedited by caching the disk drive in the main memories 12 and 22 of the computers 10 and 20 .
- one computer unit e.g. 10
- the other computer unit in this case 20
- this computer 20 relies on the cached data in its main memory without reading the recently updated data from the disk drive 14 , the system gets confused. Due to fault-tolerance, the computer units 10 and 20 have separate main memories, so that the computers 10 and 20 cannot write directly into each other's main memories which areas in the disk drive 14 they have changed.
- the object of the invention is to provide a method and a system with which two computer units can cache data in a shared disk drive in a reliable manner.
- the aims of the invention are achieved with methods and systems that are characterized by what is disclosed in the independent claims.
- the preferred embodiments are set forth in dependent claims.
- the invention is based on the idea that a computer unit desiring to use a disk drive makes sure that another computer does not use the disk drive simultaneously, whereafter the computer checks if the other computer has modified any of the data in the disk drive. If the data in the disk drive has been changed, the cached data corresponding to this data is erased from the main memory. After this, a disk task is performed and the other computer unit is informed of the changed data in the disk drive.
- the method and system according to the invention have the primary advantage that shared disk data can be controlled from two computers so that data can still be cached in the main memories of the computers. Also, the invention only requires few additions to the disk control software in order to be realized. The equipment does not usually have to be altered, considering the changes that would be required in any case by the duplexing of the computer system.
- FIG. 1 illustrating a duplexed computer unit comprising duplexed disk drives.
- the method according to the invention for controlling a shared disk drive 14 from two computers 10 and 20 can be performed in the system shown in FIG. 1 for example in the following steps. Assume that the first computer 10 wants to use the first disk drive 14 . Due to the system symmetry, the method operates in a corresponding manner from the other computer.
- the disk task may include several commands to the disk drive 14 .
- the other computer 20 must be prevented in some way from using the disk drive 14 . This is performed most advantageously in such a way that before the disk task the first computer 10 reserves the disk drive for itself for example with the SCSI command RESERVE.
- the disk drive can be released after the disk task with the SCSI command RELEASE.
- the disk drive can be released after each disk task. The release may alternatively take place only when the other computer indicates that it needs to access the disk drive. This indication of the need for the disk drive can be forwarded either via the message bus 30 or the disk drive bus 15 .
- the computer 10 does not manage to reserve the disk drive 14 , the other computer 20 has reserved the disk drive.
- the first computer 10 may then transmit to the second computer 20 indication that it needs the disk drive 14 . After this the first computer 10 may try to reserve the disk drive 14 again.
- the number or total duration of new attempts is preferably limited to a predetermined value.
- This predetermined time is selected such that the other computer 20 should be able to complete its disk task within this time and it should release the disk drive 14 .
- all signalling both between the computers 10 and 20 and from the computers to the disk drive 14 takes place via the disk drive bus 15 .
- This embodiment is applicable especially when using disk drives with SCSI interfaces, since an SCSI comprises well defined protocols by means of which also other commands, besides the commands traditionally related to disk drives, can be transmitted.
- the SCSI version II is defined in the ANSI standard X3.141-1994.
- the signalling between the computers 10 and 20 takes place via a message bus that is separate from the disk drive bus.
- This separate message bus 30 is shown in FIG. 1.
- the method according to the invention is realized most preferably as a part of the disk control software of a duplexed computer system.
- the additions according to the invention to the disk control software are stored in the memory in which the rest of the disk control software is stored. If the signalling according to the invention between the computers is performed via a message bus that is separate from the disk drive bus and that connects the computers, this message bus does not necessarily constitute known technology. On the basis of the above description, it is apparent for a person skilled in the art how the signalling on the message bus is complemented in order to implement the method according to the invention.
Abstract
Description
- The invention relates to duplexed computer systems and especially to an arrangement with which two computer units can control data on the same disk drive.
- In fault-tolerant systems that are used for example in switching centres, it is previously known to write data into two separate disk drives. It is also previously known to duplex computers so that when one computer unit fails, the other computer may continue the operation. In such a system, the active unit controls both disk drives. The passive unit is either in reserve or faulty, but at does not usually control the disk drives. It is also previously known to store in the main memory of the computer such areas of the disk drive that were read last, since it is likely that at least some of these areas (for example directories) must be read again soon.
- With reference to FIG. 1, duplexed computers are usually arranged in such a way that only one (e.g.10) of the
computers disk drive 14 and/or adisk drive 24. The other computer (in this case 20) is then in reserve or faulty. A firstdisk drive bus 15 connects both computer units and thefirst disk drive 14. Correspondingly, a seconddisk drive bus 25 connects both computer units and thesecond disk drive 24. FIG. 1 shows an embodiment where eachcomputer unit disk drive controllers computer unit disk drive buses disk drive buses disk drives bidirectional message bus 30 connecting thecomputers message bus 30 thecommuters - The system of FIG. 1 is shown with two
disk drives disk drive bus - Caching the data of the
disk drive 14 in themain memory 12 of onecomputer 10 constitutes technology that is known to a person skilled in the art. The caching is based on the empirical observation that when a disk task is performed to some part of thedisk drive 14, it is likely that another disk task is performed relatively soon to the same part. Therefore it is preferable to store in themain memory 12 the data corresponding to some of the most recently used areas of thedisk drive 14. For the purpose of caching a disk drive, a certain area is usually reserved from themain memory 12. Alternatively, thedisk drive controllers - A problem occurs with the use of duplexed computers each of which is to be provided with the possibility of using at least one
disk drive main memories computers disk drive 14, the other computer unit (in this case 20) is not necessarily aware of it. If thiscomputer 20 relies on the cached data in its main memory without reading the recently updated data from thedisk drive 14, the system gets confused. Due to fault-tolerance, thecomputer units computers disk drive 14 they have changed. - On the basis of the above, the object of the invention is to provide a method and a system with which two computer units can cache data in a shared disk drive in a reliable manner. The aims of the invention are achieved with methods and systems that are characterized by what is disclosed in the independent claims. The preferred embodiments are set forth in dependent claims.
- The invention is based on the idea that a computer unit desiring to use a disk drive makes sure that another computer does not use the disk drive simultaneously, whereafter the computer checks if the other computer has modified any of the data in the disk drive. If the data in the disk drive has been changed, the cached data corresponding to this data is erased from the main memory. After this, a disk task is performed and the other computer unit is informed of the changed data in the disk drive.
- The method and system according to the invention have the primary advantage that shared disk data can be controlled from two computers so that data can still be cached in the main memories of the computers. Also, the invention only requires few additions to the disk control software in order to be realized. The equipment does not usually have to be altered, considering the changes that would be required in any case by the duplexing of the computer system.
- The invention will be described in greater detail in connection with preferred embodiments and with reference to FIG. 1 illustrating a duplexed computer unit comprising duplexed disk drives.
- The method according to the invention for controlling a shared
disk drive 14 from twocomputers first computer 10 wants to use thefirst disk drive 14. Due to the system symmetry, the method operates in a corresponding manner from the other computer. - (i) It is checked whether the
other computer 20 has sent notices of the changes it has made in thedisk drive 14; - (ii) if the
other computer 20 has sent notices of the changes it has made in thedisk drive 14, the caching of the data corresponding to the changed areas in thedisk drive 14 is erased; - (iii) a disk task is performed;
- (iv) if the data in the
disk drive 14 is changed in the disk task, the other computer is informed of the changed areas in-thedisk drive 14. - The disk task may include several commands to the
disk drive 14. During this process theother computer 20 must be prevented in some way from using thedisk drive 14. This is performed most advantageously in such a way that before the disk task thefirst computer 10 reserves the disk drive for itself for example with the SCSI command RESERVE. Correspondingly, the disk drive can be released after the disk task with the SCSI command RELEASE. The disk drive can be released after each disk task. The release may alternatively take place only when the other computer indicates that it needs to access the disk drive. This indication of the need for the disk drive can be forwarded either via themessage bus 30 or thedisk drive bus 15. - If the
computer 10 does not manage to reserve thedisk drive 14, theother computer 20 has reserved the disk drive. Thefirst computer 10 may then transmit to thesecond computer 20 indication that it needs thedisk drive 14. After this thefirst computer 10 may try to reserve thedisk drive 14 again. - The number or total duration of new attempts is preferably limited to a predetermined value. This predetermined time is selected such that the
other computer 20 should be able to complete its disk task within this time and it should release thedisk drive 14. Alternatively, there may be two predetermined time limits. The shorter time limit (for example 5 seconds) is used for short reservations, and the longer one (which may be several minutes) is used for long reservations, for instance during formatting and packing the disk drive. - Unless the
other computer 20 releases thedisk drive 14 in a time corresponding to the predetermined limit, an inquiry can be sent to thiscomputer 20 asking if it has reserved thedisk drive 14. Unless an expected answer is received for this inquiry, it is concluded that theother computer 20 has become faulty while performing a disk task. In this case, a reset command is transmitted to thedisk drive 14 and a new attempt for reservation is performed. - According to an embodiment of the invention, all signalling both between the
computers disk drive 14 takes place via thedisk drive bus 15. This embodiment is applicable especially when using disk drives with SCSI interfaces, since an SCSI comprises well defined protocols by means of which also other commands, besides the commands traditionally related to disk drives, can be transmitted. The SCSI version II is defined in the ANSI standard X3.141-1994. - According to another embodiment of the invention, the signalling between the
computers separate message bus 30 is shown in FIG. 1. - The method according to the invention is realized most preferably as a part of the disk control software of a duplexed computer system. The additions according to the invention to the disk control software are stored in the memory in which the rest of the disk control software is stored. If the signalling according to the invention between the computers is performed via a message bus that is separate from the disk drive bus and that connects the computers, this message bus does not necessarily constitute known technology. On the basis of the above description, it is apparent for a person skilled in the art how the signalling on the message bus is complemented in order to implement the method according to the invention.
- From the above description it is also obvious for a person skilled in the art that as the technology advances, the basic idea of the invention can be realized in many different ways. The invention and the embodiments thereof are therefore not restricted to the above-described examples, but they may vary within the scope of the claims.
Claims (10)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI954333 | 1995-09-14 | ||
FI954333A FI102788B (en) | 1995-09-14 | 1995-09-14 | Control of shared disk data in a duplicate computer unit |
PCT/FI1996/000484 WO1997010552A1 (en) | 1995-09-14 | 1996-09-13 | Controlling shared disk data in a duplexed computer unit |
Publications (2)
Publication Number | Publication Date |
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US20010011331A1 true US20010011331A1 (en) | 2001-08-02 |
US6393518B2 US6393518B2 (en) | 2002-05-21 |
Family
ID=8544021
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/043,195 Expired - Lifetime US6393518B2 (en) | 1995-09-14 | 1996-09-13 | Controlling shared disk data in a duplexed computer unit |
Country Status (12)
Country | Link |
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US (1) | US6393518B2 (en) |
EP (1) | EP0850452B1 (en) |
JP (1) | JPH11512540A (en) |
CN (1) | CN1111803C (en) |
AU (1) | AU713441B2 (en) |
BR (1) | BR9610497A (en) |
CA (1) | CA2231872A1 (en) |
DE (1) | DE69617709T2 (en) |
ES (1) | ES2166463T3 (en) |
FI (1) | FI102788B (en) |
RU (1) | RU2190873C2 (en) |
WO (1) | WO1997010552A1 (en) |
Cited By (2)
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US20120066467A1 (en) * | 2010-03-15 | 2012-03-15 | International Business Machines Corporation | Using a dual mode reader writer lock |
CN103605618A (en) * | 2013-11-20 | 2014-02-26 | 浪潮电子信息产业股份有限公司 | Non-write-back mirror image and direct write switching method for cache mirror image system |
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JP3944449B2 (en) * | 2002-12-19 | 2007-07-11 | 株式会社日立製作所 | Computer system, magnetic disk device, and disk cache control method |
CN100363929C (en) * | 2004-07-31 | 2008-01-23 | 鸿富锦精密工业(深圳)有限公司 | Directory control and management syste mand method with allowable tolerance |
US7418567B2 (en) * | 2004-11-30 | 2008-08-26 | International Business Machines Corporation | Cache for an enterprise software system |
US20100332762A1 (en) * | 2009-06-30 | 2010-12-30 | Moga Adrian C | Directory cache allocation based on snoop response information |
US8612676B2 (en) | 2010-12-22 | 2013-12-17 | Intel Corporation | Two-level system main memory |
AU2012273166A1 (en) * | 2011-06-19 | 2014-01-23 | Viamet Pharmaceuticals (NC), Inc. | Metalloenzyme inhibitor compounds |
CN107391397B (en) | 2011-09-30 | 2021-07-27 | 英特尔公司 | Memory channel supporting near memory and far memory access |
US10275160B2 (en) | 2015-12-21 | 2019-04-30 | Intel Corporation | Method and apparatus to enable individual non volatile memory express (NVME) input/output (IO) Queues on differing network addresses of an NVME controller |
US10200376B2 (en) | 2016-08-24 | 2019-02-05 | Intel Corporation | Computer product, method, and system to dynamically provide discovery services for host nodes of target systems and storage resources in a network |
US10176116B2 (en) | 2016-09-28 | 2019-01-08 | Intel Corporation | Computer product, method, and system to provide discovery services to discover target storage resources and register a configuration of virtual target storage resources mapping to the target storage resources and an access control list of host nodes allowed to access the virtual target storage resources |
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US4164787A (en) * | 1977-11-09 | 1979-08-14 | Bell Telephone Laboratories, Incorporated | Multiple microprocessor intercommunication arrangement |
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US5297260A (en) * | 1986-03-12 | 1994-03-22 | Hitachi, Ltd. | Processor having a plurality of CPUS with one CPU being normally connected to common bus |
DE3688136T2 (en) | 1986-04-04 | 1993-10-07 | Ibm | Procedure for testing and putting data into a record on a disk in an atomic I / O operation. |
US4959777A (en) * | 1987-07-27 | 1990-09-25 | Motorola Computer X | Write-shared cache circuit for multiprocessor system |
US5072369A (en) * | 1989-04-07 | 1991-12-10 | Tektronix, Inc. | Interface between buses attached with cached modules providing address space mapped cache coherent memory access with SNOOP hit memory updates |
AU633724B2 (en) * | 1990-06-29 | 1993-02-04 | Digital Equipment Corporation | Interlock queueing |
US5287473A (en) | 1990-12-14 | 1994-02-15 | International Business Machines Corporation | Non-blocking serialization for removing data from a shared cache |
JPH0827755B2 (en) | 1991-02-15 | 1996-03-21 | インターナショナル・ビジネス・マシーンズ・コーポレイション | How to access data units at high speed |
KR960003065B1 (en) * | 1991-12-10 | 1996-03-04 | 후지쓰 가부시끼가이샤 | Information processing apparatus |
US5408653A (en) * | 1992-04-15 | 1995-04-18 | International Business Machines Corporation | Efficient data base access using a shared electronic store in a multi-system environment with shared disks |
JPH07200386A (en) * | 1993-12-28 | 1995-08-04 | Toshiba Corp | Access controller for shared memory and image forming device |
US5574902A (en) * | 1994-05-02 | 1996-11-12 | International Business Machines Corporation | Efficient destaging of updated local cache pages for a transaction in a multisystem and multiprocess database management system with a high-speed shared electronic store |
-
1995
- 1995-09-14 FI FI954333A patent/FI102788B/en not_active IP Right Cessation
-
1996
- 1996-09-13 US US09/043,195 patent/US6393518B2/en not_active Expired - Lifetime
- 1996-09-13 RU RU98107133/09A patent/RU2190873C2/en not_active IP Right Cessation
- 1996-09-13 CA CA002231872A patent/CA2231872A1/en not_active Abandoned
- 1996-09-13 CN CN96196941A patent/CN1111803C/en not_active Expired - Fee Related
- 1996-09-13 BR BR9610497A patent/BR9610497A/en not_active IP Right Cessation
- 1996-09-13 ES ES96930187T patent/ES2166463T3/en not_active Expired - Lifetime
- 1996-09-13 JP JP9511683A patent/JPH11512540A/en active Pending
- 1996-09-13 EP EP96930187A patent/EP0850452B1/en not_active Expired - Lifetime
- 1996-09-13 WO PCT/FI1996/000484 patent/WO1997010552A1/en active IP Right Grant
- 1996-09-13 DE DE69617709T patent/DE69617709T2/en not_active Expired - Lifetime
- 1996-09-13 AU AU69329/96A patent/AU713441B2/en not_active Ceased
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20120066467A1 (en) * | 2010-03-15 | 2012-03-15 | International Business Machines Corporation | Using a dual mode reader writer lock |
US8347045B2 (en) * | 2010-03-15 | 2013-01-01 | International Business Machines Corporation | Using a dual mode reader writer lock |
CN103605618A (en) * | 2013-11-20 | 2014-02-26 | 浪潮电子信息产业股份有限公司 | Non-write-back mirror image and direct write switching method for cache mirror image system |
Also Published As
Publication number | Publication date |
---|---|
FI102788B1 (en) | 1999-02-15 |
CN1196130A (en) | 1998-10-14 |
BR9610497A (en) | 1999-03-30 |
EP0850452B1 (en) | 2001-12-05 |
AU713441B2 (en) | 1999-12-02 |
WO1997010552A1 (en) | 1997-03-20 |
EP0850452A1 (en) | 1998-07-01 |
US6393518B2 (en) | 2002-05-21 |
AU6932996A (en) | 1997-04-01 |
DE69617709T2 (en) | 2002-08-08 |
FI102788B (en) | 1999-02-15 |
DE69617709D1 (en) | 2002-01-17 |
JPH11512540A (en) | 1999-10-26 |
FI954333A0 (en) | 1995-09-14 |
FI954333A (en) | 1997-03-15 |
RU2190873C2 (en) | 2002-10-10 |
CA2231872A1 (en) | 1997-03-20 |
CN1111803C (en) | 2003-06-18 |
ES2166463T3 (en) | 2002-04-16 |
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