Method and system for maintaining concurrent data access during device upgrade
First Claim
1. In a data storage system including a plurality of direct access storage devices, each having a fixed number of unique addresses and the same number of logical volumes, and a storage controller being connected to each of the plurality of direct access storage devices, a method of maintaining concurrent data access while upgrading at least one of said plurality of direct access storage devices containing data and coupled to a host computer via a channel comprising the steps of:
- responsive to receipt of a request to upgrade said at least one of said plurality of direct access storage devices data over a channel, copying said data to another one of said plurality of direct access storage devices having no data;
logically mapping said fixed number of unique addresses of said at least one of said plurality of direct access storage devices to said another one of said plurality of direct access storage devices to which said data has been copied;
removing said at least one of said plurality of direct access storage devices;
upgrading said at least one of said plurality of direct access storage devices with a direct access storage device having a greater number of unique addresses;
reconfiguring said storage controller to accommodate said greater number of unique addresses;
recopying said data to said upgraded direct access storage device into said greater number of unique addresses; and
logically remapping said unique addresses of said another of said plurality of direct access storage devices to said greater number of unique addresses of said upgraded direct access storage to which said data has been recopied.
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Accused Products
Abstract
A system and method for changing the number of logical volumes in a drawer in a rack in a direct access storage device subsystem is disclosed. The method and system are able to change the number of logical volumes without disrupting access to the other logical volumes in the rack. Channel connection addresses, which are logical volume addresses as known by the CPUs, are freed by removing the old drawer and then are mused. If the new drawer has more logical volumes than the old drawer, the next unused channel connection addresses are used with the new drawer. In a subsystem having a storage controller for providing control for a plurality of direct access storage devices, the logical volumes are spread across multiple physical devices. The storage controller maintains configuration data for the entire subsystem in redundant, non-volatile storage locations reserved specifically for its use. Each logical volume address for the rack is set by the drawer location and the logical sequence of the volumes within the drawer. As drawers are installed, the control unit sequentially assigns the volume addresses for the control unit and the channel connection addresses for the CPUs.
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Citations
13 Claims
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1. In a data storage system including a plurality of direct access storage devices, each having a fixed number of unique addresses and the same number of logical volumes, and a storage controller being connected to each of the plurality of direct access storage devices, a method of maintaining concurrent data access while upgrading at least one of said plurality of direct access storage devices containing data and coupled to a host computer via a channel comprising the steps of:
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responsive to receipt of a request to upgrade said at least one of said plurality of direct access storage devices data over a channel, copying said data to another one of said plurality of direct access storage devices having no data; logically mapping said fixed number of unique addresses of said at least one of said plurality of direct access storage devices to said another one of said plurality of direct access storage devices to which said data has been copied; removing said at least one of said plurality of direct access storage devices; upgrading said at least one of said plurality of direct access storage devices with a direct access storage device having a greater number of unique addresses; reconfiguring said storage controller to accommodate said greater number of unique addresses; recopying said data to said upgraded direct access storage device into said greater number of unique addresses; and logically remapping said unique addresses of said another of said plurality of direct access storage devices to said greater number of unique addresses of said upgraded direct access storage to which said data has been recopied. - View Dependent Claims (2, 3, 4)
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5. In a data processing system having a plurality of host computers, a storage system including a plurality of direct access storage devices, each having a fixed number of logical addresses, and a storage controller, the storage controller being connected to each of the plurality of direct access storage devices by a storage path and to each of the host computers by at least a first channel and further capable of managing a fixed number of logical addresses, and of managing the upgrading of at least one of said direct access storage devices, the storage controller comprising:
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means responsive to receipt of an upgrade request for dynamically increasing the number of logical addresses associated with at least one of said plurality of direct access storage devices; means for copying data between any two of said plurality of direct access storage devices; means for reassigning the logical address from one of said plurality of said direct access storage devices to a second one of said plurality of said direct access storage devices receiving said data so as to maintain access to said data during an on-line condition; and means for logically removing said at least one of said plurality of said direct access storage devices thereby allowing said means for dynamically increasing the number of logical addresses to increase the number of logical addresses corresponding to said at least one of said plurality of direct access storage devices when replaced with a direct access storage device having a greater fixed number of addresses, such that data be may stored within a greater fixed number of addresses within said replacement direct access storage device. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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Specification