Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique
Reexamination Certificate
2003-04-10
2004-07-06
Lane, Jack A. (Department: 2188)
Electrical computers and digital processing systems: memory
Storage accessing and control
Control technique
C707S793000
Reexamination Certificate
active
06760823
ABSTRACT:
STATEMENTS REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
FIELD OF THE INVENTION
This invention relates generally to backup storage systems and more particularly to a system and method for efficiently mapping information from a primary processing system to a backup storage system.
BACKGROUND OF THE INVENTION
As is known in the art, computer systems which process and store large amounts of data typically include a primary processor coupled to a shared storage system in which the data is stored. The primary processor performs its operations using the storage system. To minimize the chance of data loss, the computer systems also can include a backup storage system coupled to the primary processor and the storage system. Often the connection between the primary processor and the backup storage system is through a network in which case the primary processor is sometimes referred to as a “client processor” or more simply a “client.”
The backup storage system can include a backup storage device (which may include disk drives, tape storage or any other storage mechanism), together with a system for placing data into the storage device and recovering the data from that storage device. To perform a backup, the client copies data from the shared storage system across the network to the backup storage system. Thus, an actual data file may be communicated over the network to the backup storage device.
The shared storage system corresponds to the actual physical storage. For the client to write the backup data over the network to the backup storage system, the client first converts the backup data into file data—i.e., the client retrieves the data from the physical storage system level, and converts the data into application level format (e.g. a file) through a logical volume manager level, a file system level and the application level. When the backup storage device receives the data file, the backup storage system can take the application level data file, and convert it to its appropriate file system level format for the backup storage system. The data can then be converted through the logical volume manager level and into physical storage.
This form of backing up data may be referred to as “logical-logical” backup. That is, the logical data is backed up on the backup storage device. The data to be backed up is presented independent of the manner in which it is physically stored on the shared storage system at the physical storage system level, independent of the file system level mechanisms on the client, and independent of how data is stored on the backup storage device.
Logical-logical backup can be a particularly convenient form of backup. The backup storage system, however, may need to be capable of interaction with a variety of different clients. For example, it may be desirable to have a backup storage system that can backup data from both a Solaris operating system and HP-UX operating system. By providing logical level data across the network to the backup storage system, the backup storage system can take that data and convert the data location as appropriate for storage in its own physical storage system (i.e., take the data at the application level and convert it to the file system level, logical volume manager and physical storage system, as each of those levels is possibly uniquely implemented in the backup storage system). Thus, if the client is running the HP-UX operating system and the backup storage system is using a Solaris operating system, the backup storage system can save and retrieve data according to the formats used in the Solaris operating system. If data were copied directly from the storage system to the backup storage system, the stored data would depend on the file system level formats for the client (here, HP-UX). The backup storage system would then be unable to read or examine that data because it uses different file system level formats (here, Solaris).
One problem with such a backup system, however, is that the backup process requires significant traffic on the network. Moreover, if the,network medium is crowded with traffic or can not support high speed data transfer, the backup process can be slow. In addition, this architecture may require significant resources of the client or the storage system. The client and the storage system must fully parse the data from the physical storage level to the application level. Thus, this approach requires a relatively large amount of system resources and time to complete transfers. This is particularly true when there is a large amount of data to back up.
The EMC Data Manager (EDM) line of products is capable of logical-logical backup and restore over a network, as described in numerous publications available from EMC, including the EDM User Guide (Network) “Basic EDM Product Manual”.
To overcome the above problems, a backup storage architecture in which a direct connection is established between the shared storage system and the backup storage system was conceived. Such a system is described in U.S. Pat. No. 6,047,294, assigned to assignee of the present invention, and entitled Logical Restore from a Physical Backup in Computer Storage System. In this approach, the backup storage system may be a system as generally described in EMC Data Manager: Symmetrix Connect User Guide, P/N 200-113-591, Rev. C, December 1997, available from EMC Corporation of Hopkinton, Mass. The direct connection between the shared storage system and the backup storage system may be provided as a high speed data channel, such as a SCSI cable or one or more fiber-channel cables. In this system, a user may be permitted to backup data over the network or the direct connection.
When the shared storage system is a Symmetrix product, the direct connection may be connected from the backup storage system to the storage system through a host adaptor. For high speed data transfer using the direct connection approach, data may be copied directly from physical storage devices to the backup storage system.
The shared storage system can be provided from a plurality of different physical storage devices. Each of the respective physical devices can include contiguous segments of storage which must be backed up. These contiguous segments of storage may, but need not, be of the same size. The segments of storage are sometimes referred to as “hyper-volumes.” Thus, hyper volumes correspond to segments of physical storage that can be used as components when constructing a virtual volume for use by the file system
With respect to a back-up scenario, however, the task remains of determining which hyper-volumes (or portions of hyper-volumes) should be backed up and communicating this information to the backup storage device. For example, consider backup for data base files in an Oracle data base application (such as Oracle versions 7.2.x, 7.3.x and 8.0.4, available from Oracle Corp. of Redwood, Calif.). Files may be stored on any one, or across any number, of hyper-volumes located in any particular set of locations across one or more physical storage devices.
To provide an approach which allows mapping of individual files, a technique was conceived in which a structure representing each contiguous piece of disk storage was passed between the client and the backup storage system. Thus, in the prior art approach to backing up data, each 128 kilobytes (KB) of storage memory in the shared storage system is represented by a block of memory (or more simply “a block”), a beginning offset value and a length. The beginning offset value and length define a so-called extent.
In any particular system, each block is typically of the same predetermined size. Different systems, however, can utilize different size blocks. The particular size of a block used in any particular system is selected in accordance with the requirements and capabilities of that system. In one system, for example, it may be preferable to utilize a block size of one-hundred bytes while in a different system, it may be it may be preferable to utilize a block size of two-hundred bytes. One problem wi
Daly, Crowley & Mofford LLP
EMC Corporation
Lane Jack A.
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