1. In a clustering system having primary and secondary host computers coupled to a storage system and a management computer, wherein the primary and secondary host computers include cluster management functions which communicate with each other, wherein the management computer includes a volume security control function, wherein the storage system includes a LUN security function therein so that one or more predetermined host computers of the clustering system can access at least one of a plurality of logical units in the storage system, a method comprising:
negotiating to determine ownership of access to a specific logical unit of the logical units by the cluster management functions of the host computers, such that the primary host computer has ownership of access to the specific logical unit and the secondary host computer does not have ownership of access to the specific logical unit;
reserving a storage resource for the specific logical unit of the logical units for an access control;
notifying information of the ownership to the volume security control function in the management computer by the host computers;
storing access control information in the storage system, in connection with host identification information and logical unit identification information, wherein the access control information is used by the storage system to control access from different host computers to the specific logical unit in the storage system, wherein the LUN security function in the storage system allows the primary host computer to access the specific logical unit and disallows the secondary host computer to access the specific logical unit based on the access control information;
changing ownership of access to the specific logical unit by the cluster management functions in the host computers, such that the primary host computer releases ownership of access to the specific logical unit and the secondary host computer reserves ownership of access to the specific logical unit;
notifying information of the changing ownership to the volume security control function in the management computer by the host computers;
based on the information provided by the cluster management functions, coordinating management of security for the specific logical unit by the volume security control function in the management computer based on corresponding information to the access control information, the corresponding information to the access control information being stored in the management computer; and
changing the access control information in the storage system, for disallowing the primary host computer to access the specific logical unit and allowing the secondary host computer to access the specific logical unit based on a request from the volume security control function of the management computer; and
verifying the consistency of the access control information in the storage system by one or more of the cluster management functions in the host computers, wherein if the consistency of the access control information is not verified, the one or more of the cluster management functions in the host computers release the reserved storage resource, reset the access control information and start the negotiation to determine ownership of access to a specific logical unit of the logical units again.
2. The method according to claim 1, wherein a heartbeat communication protocol is used to detect said change of access control information.
3. The method according to claim 1, wherein said management computer includes a storage configuration information table; wherein said storage configuration information table is set by using World Wide Name.
4. The method according to claim 1, wherein the access control information is used by the storage system to allow one of the host computers to access the specific logical unit and to disallow another one of the host computers to access the specific logical unit in the storage system.
5. The method according to claim 1, wherein the access control information is used by the storage system to control access from different host computers to different specific logical units in the storage system.
6. The method according to claim 5, wherein the access control information is used by the storage system to (i) allow a first one of the host computers to access a first specific logical unit and to disallow a second one of the host computers to access the first specific logical unit in the storage system, and (ii) allow the second one of the host computers to access a second specific logical unit and to disallow the first one of the host computers to access the second specific logical unit in the storage system.
The claims below are in addition to those above.
All refrences to claims which appear below refer to the numbering after this setence.
1. An electrophotographic transfer paper having a substrate and a thermoplastic foamed resin layer which is provided on at least one surface of the substrate and has pores, wherein the temperature at which the viscosity of the thermoplastic foamed resin layer becomes 1\xd7104 Pa\xb7s ranges from 60\xb0 C. to 100\xb0 C. and a gradient R of a viscosity-temperature curve of the thermoplastic foamed resin layer defined by the following Equation (1) ranges from 0.02 to 0.10:
R={Log(\u03b7t)\u2212Log(\u03b7t+20)}20 \u2003\u2003(1)
where \u03b7t indicates 1\xd7104 Pa\xb7s and \u03b7t+20 indicates the viscosity (Pa\xb7s) of the thermoplastic foamed resin layer at a temperature higher by 20\xb0 C. than the temperature showing the viscosity \u03b7t.
2. An electrophotographic transfer paper having a substrate whose air permeability is lower than 1000 seconds and a thermoplastic foamed resin layer which is provided on at least one surface of the substrate and has pores, wherein the temperature at which the viscosity of the thermoplastic foamed resin layer becomes 1\xd7104 Pa\xb7s ranges from 60\xb0 C. to 100\xb0 C. and a gradient R of a viscosity-temperature curve of the thermoplastic foamed resin layer defined by the following Equation (1) ranges from 0.015 to 0.10:
R={Log(\u03b7t)\u2212Log(\u03b7t+20)}20\u2003\u2003(1)
where \u03b7t indicates 1\xd7104 (Pa\xb7s) and \u03b7t+20 indicates the viscosity (Pa\xb7s of the thermoplastic foamed resin layer at a temperature higher by 20\xb0 C. than the temperature showing the viscosity \u03b7t.
3. An electrophotographic transfer paper according to claim 2, wherein the gradient R ranges from 0.018 to 0.09.
4. An electrophotographic transfer paper having a substrate whose air permeability is not lower than 1000 seconds and a thermoplastic foamed resin layer which is provided on at least one surface of the substrate and has pores, wherein the temperature at which the viscosity of the thermoplastic foamed resin layer becomes 1\xd7104 Pa\xb7s ranges from 60\xb0 C. to 100\xb0 C. and a gradient R of a viscosity-temperature curve of the thermoplastic foamed resin layer defined by the following Equation (1) ranges from 0.02 to 0.15:
R={Log(\u03b7t)\u2212Log(\u03b7t+20)}20\u2003\u2003(1)
where \u03b7t indicates 1\xd710 4 Pa\xb7s and \u03b7t+20 indicates the viscosity (Pa\xb7s) of the thermoplastic foamed resin layer at a temperature higher by 20\xb0 C. than the temperature showing the viscosity \u03b7t.
5. An electrophotographic transfer paper according to claim 4, wherein the gradient R ranges from 0.04 to 0.12.
6. An electrophotographic transfer paper according to claim 1, wherein an average diameter of pores on a surface of the thermoplastic foamed resin layer ranges from 1.5 \u03bcm to 80 \u03bcm.
7. An electrophotographic transfer paper according to claim 1, wherein the average diameter of the pores on the surface of the thermoplastic foamed resin layer ranges from 2 \u03bcm to 60 \u03bcm.
8. An electrophotographic transfer paper according to claim 1, wherein a ratio of the number of pores having diameters not lower than 80 \u03bcm to the number of all pores t on the surface of a thermoplastic foamed resin layer (pores having diameters not lower than 80 \u03bcmall pores) is not more than 20%.
9. An electrophotographic transfer paper according to claim 1, wherein the ratio of the number of the pores having diameters not lower than 80 \u03bcm to the number of all the pores on the surface of the thermoplastic foamed resin layer (pores having diameters not lower than 80 \u03bcmall pores) is not more than 5%.
10. An electrophotographic transfer paper according to claims 1, wherein the ratio of the area of pores on a surface of the thermoplastic foamed resin layer to the area of the entire surface ranges from 10% to 80%.
11. An electrophotographic transfer paper according to claim 1, wherein the ratio of the area of the pores on the surface of the thermoplastic foamed resin layer to the area of the entire surface ranges from 20% to 70%.
12. An electrophotographic transfer paper according to claim 1, wherein an amount of coating per single side of the substrate of the thermoplastic foamed resin layer ranges from 2 gm2 to 40 gm2 in terms of dry mass.
13. An electrophotographic transfer paper according to claim 1, wherein the amount of coating per single side of the substrate of the thermoplastic foamed resin layer ranges from 5 gm2 to 30 gm2 in terms of dry mass.
14. An electrophotographic transfer paper according to claim 1, wherein the thermoplastic foamed resin layer contains a release agent.
15. An electrophotographic transfer paper according to claim 14, wherein the release agent is selected from waxes, higher fatty acids, higher alcohols, higher fatty amides, and silicone oils.
16. An electrophotographic transfer paper according to claim 14, wherein the thermoplastic foamed resin layer contains the release agent in an amount ranging from 0.1 mass % to 20 mass %.
17. An electrophotographic transfer paper according to claim 1, wherein a resin used for the thermoplastic foamed resin layer is a polyester resin.
18. An electrophotographic transfer paper according to claim 1, wherein a resin used for the thermoplastic foamed resin layer is a styrene-acrylic resin.
19. An electrophotographic transfer paper according to claim 1, wherein a resin used for the thermoplastic foamed resin layer is a material in which at least two thermoplastic resins are blended.
20. The electrophotographic transfer paper according to claim 2, wherein the air permeability of the substrate is not lower than 10 sec.
21. The electrophotographic transfer paper according to claim 4, wherein the air permeability of the substrate is not more than 20,000 sec.