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A consistent view of data
If the mainframe is used to increase recovery success rates for most mixed environments, there must be a consistent view of the data at a point in time, called consistency groups. The ability to gather data from various platforms at the same time is available with products from most major mainframe/open storage vendors, such as EMC Corp., Hitachi Data Systems (HDS) Inc. and IBM Corp. EMC's TimeFinder and HDS' ShadowImage can coordinate I/O freezing for a database at the host level. IBM's FlashCopy performs this task at the array level. Achieving tight coordination of hosts, applications and data access requires scripting and programming job-scheduling packages to quiesce the application and flush the data.
For example, EMC's solution for Symmetrix storage environments combines its TimeFinder software with IDP's FDRSOS and FDR/Upstream/SOS. The combination provides a point-in-time copy of critical data across multiple platforms.
FDR/Upstream/SOS reads the data off the open-systems disk (which can be a SAN disk, local disk or a LAN logical disk) and writes it to the specially formatted FDRSOS disk on the SAN. The FDR/Upstream OS/390 component then takes the data off the SAN disk and writes it to tape. This process is transparent to the administrator and results in a highly reliable, high-speed solution for LAN and SAN environments. Backups don't go across the network, but travel through the mainframe's ESCON or FICON connection. And open-systems storage administrators aren't held hostage by a mainframe-only process because they can perform their own backups or file-level recovery using a Java-based browser interface.
Organizations can orchestrate all of the dependent steps using mainframe job schedulers such as Allen Systems Group (ASG) Inc.'s ASG-Zeke, Computer Associates (CA) International Inc.'s Unicenter CA-Jobtrac Job Management, IBM's CA7 utility as well as open-systems schedulers such as CRON. With this approach, data is backed up using mainframe resources and staff in a consistent manner. This approach also provides the benefits of LAN- and server-free backups. All the work of backup and recovery is done by the mainframe, so fewer open-systems resources are used.
This was first published in November 2005