Enterprise systems/network management vendors are integrating SAN management into their frameworks to eventually provide centralized LAN/SAN monitoring and control.
By Harriett Bennett
The storage industry is moving closer to fulfilling SAN promises with the launch of a new wave of SAN management software this year. Strategies from large software developers and system vendors promise to provide completely integrated solutions encompassing network administration, storage virtualization, and device topology management.
Other players in the SAN market are seizing the opportunity to develop software modules in one or more key areas of SAN management that will interoperate and integrate with complementary products to create heterogeneous solutions. All are working toward the common SAN goals of unconstrained access to a virtual pool of storage, centralized storage management, increased availability and reliability, and greatly reduced cost of ownership.
In the broadest sense of the term, SAN management software includes products that provide storage consolidation and sharing, administration, access, security, and other services. Functionality such as volume management, image snapshots, remote mirroring, and server-less backup all contribute to the overall benefits of SANs. The topology of the physical devices must also be managed and assimilated with logical storage. To complete the picture of comprehensive SAN management, these services will need to interface with enterprise management frameworks from leading vendors.
Network and systems management software can be integrated with SAN management to create a pool of storage that applications can access, all under some type of centralized control. Many companies with management infrastructures in place are planning to implement SANs that can be managed using existing frameworks. As SAN management software continues to evolve, "storage on demand" will require less and less human intervention and overall quality of service (QoS) will increase commensurately.
From an enterprise perspective, SANs are subnetworks that provide storage resources to any and all applications and network-based services. To maximize the use of storage assets, as well as increase availability and fault tolerance, SAN management must be integral to the management of enterprise IT as a whole. With centralized, policy-based control of SANs, along with other networks across the enterprise, IT departments can more effectively manage performance, growth, and costs.
In the current state of SAN software, lack of interoperability is still the gating factor holding back widespread deployment of SANs. To close the gap, leading enterprise management software vendors, including Computer Associates, Hewlett-Packard, and IBM/Tivoli, are aiming to leverage their installed bases by offering integrated solutions from the application management level to the device management level, with the assurance of compatibility from a single source provider and certified partners. Ideally, users will benefit by being able to add SAN management functionality to their existing IT management infrastructure.
The emergence of SANs adds another type of network to be brought into the collective view of IT operations. The visions of the three major enterprise network management frameworks, CA's Unicenter, HP's OpenView, and Tivoli's NetView, encompass the integration of their platforms' backup/restore, hierarchical storage management, device topology management, and asset management applications. Each of these vendors is making headway toward integrating its own storage management software with its own network management infrastructure, as well as that of the others. Likewise, they are committed to providing APIs and integration tools so that their network management frameworks can support a heterogeneous environment of server, network, and storage systems. Predictably, the most robust configurations for this tiered network-to-device management are currently available as pre-tested, single-source solutions from these vendors.
As comprehensive storage management protocols and standards congeal, it will be interesting to see how much, if any, leverage the network management vendors can gain in the storage management software market over suppliers that strive for "best of breed" solutions in one or more areas of SAN management.
CA brings SANITI
Computer Associates' SAN Integrated Technol-ogy Initiative (SANITI) proposes enterprise-to-device-level SAN support, leveraging CA's manager/agent architecture. SANITI is intended to be an SNMP-based open standard that facilitates multi-vendor solutions, and that operates within the Unicenter TNG Framework. CA's strategy is to provide policy-based management operations for heterogeneous platforms through an enterprise's networks.
In the SANITI initiative, existing storage solutions operating under CA's ArcServeIT can be used in a SAN configuration. ArcServIT's SAN-oriented features include LAN-free backup, software RAID support, image snapshots, data migration, and replication on switched SAN fabrics. With the Unicenter TNG Framework Advanced Storage Option (ASO), all networked LAN and WAN devices and SAN objects are automatically detected and displayed as 2D or 3D topologies. From a single console, users can manage multiple platforms with Unicenter commands, or by launching applets from the console's GUI.
This year, CA's focus will be on expanding support for heterogeneous platforms, as well as porting HSM (hierarchical storage management) and Replication for SAN transport, while continuing to blend enterprise management, media management, and asset management into SAN configurations. CA plans to utilize its "Neugents predictive analysis" technology for increased SAN availability. Resource pooling, zoning, and sharing will also be available as part of Unicenter TNG, as will support for SAN file systems and network-attached storage (NAS).
As part of the HP Equation Architecture, HP's SureStore E storage management software is designed to integrate with system management platforms, such as its own OpenView. With OpenView's extensible SNMP agent available for HP-UX and Solaris, independent storage applications can converge with Open View's IT management functions. HP's OmniBack II backup/recovery software and OmniStorage client/server-based HSM are already part of the OpenView infrastructure.
HP has taken additional steps to integrate its SureStore E products into OpenView's service-level management tools with the introduction of SureStore E Command View XP for a consolidated GUI presentation for HP's XP Disk Array management applications. Also shipping is OpenView SPI for XP Disk Arrays, a device management extension for OpenView environments. HP Sure Store E Command View XP provides a console for XP device and LUN management and can be used with SureStore E SAN Manager Device Management (DM), which auto-discovers and maps devices on a SAN. E SAN Manager DM employs Java technology for portability, and allows device management applications to be integrated through command line interfaces.
SureStore E SAN Manager LUN Management (LM) is HP's offering for storage access management. A storage administrator interacts with a configuration database residing on a Windows NT server (with Solaris and other Unix support on the way) to allocate storage to a client running SAN Manager LM. Because of the level at which SAN Manager LM interfaces to server operating systems, almost any application and standard file system is supported. High availability requirements are addressed through mirrored configuration databases.
Tivoli began delivering on its Information Integrity Initiative with the 1999 rollout of Tivoli Storage Manager, the cornerstone of the company's application-centric data management architecture.
The Tivoli Storage Manager server is built on top of a relational semantic database and interacts with Tivoli data protection and disaster recovery applications, as well as IBM's Network Storage Manager and Virtual Tape Server. The current version of Tivoli Storage Manager includes network backup and tape sharing, along with "adaptive differencing" technology for bandwidth optimization in remote backup and restore operations.
Tivoli has also made moves to integrate the management of SANs, LANs, and WANs into a centralized framework with single console control. The SAN Extension toolkit for NetView enables the company's partners to integrate their products with Tivoli software, or embed the Tivoli Management Agent (TMA) in their software. The toolkit expands NetView's capability to assemble and monitor SAN device information in an aggregate view of enterprise networks. Other Tivoli tool sets that reach toward enterprise-echelon management of data movement include Decision Support for Storage Management Analysis and Space Manager for HSM.
On the logical side of storage management, Tivoli's SANergy is client/server software for simultaneous file sharing among computers on a SAN. A Meta-Data Controller, based on extensions to Windows NT/2000 or Solaris file systems, manages access to SAN storage by Windows, Unix, and Macintosh systems running SANergy client software.
IBM is also working on a new generation of application storage subsystems that will take disk resource pooling to the level of virtualization. Internally dubbed StorageTank, this virtualization scheme is expected to be in the form of a storage domain server[HLB2]. IBM expects to announce software based on this technology in early 2001.
SAN pooling and sharing
Storage device and topology management products are clearly on the way to becoming a critical part of centralized IT management, as evidenced by the support of third-party products, such as Vixel's SAN InSite 2000 and Veritas' SANPoint, within leading network management infrastructures. The power and efficiency of SANs will escalate even more dramatically when the management of logical storage is incorporated at the enterprise level and driven by applications and their automated policies.
At the core of SAN management is the software that enables storage to be shared. This software transforms the disparate storage devices on the SAN into a virtual pool of storage that can be accessed by any authorized host, and managed from a central location.
In storage sharing schemes, the physical/logical relationships (which are currently used to form LUNs) are broken and a virtualization layer is formed between the file systems and physical assets. The virtualization layer maps the file systems to the physical assets and manages the process of storage allocation and configuration such that all of the storage devices on the SAN can potentially appear as a single (or multiple) disk image accessible by any SAN-enabled server.
There are several ways of implementing data, file, or storage sharing, and they differ in terms of where the control of assets is executed. A key differentiator is whether or not storage management control is in the data path ("in-band") or handled over the LAN ("out-of-band"). An in-band implementation introduces a storage domain server, or SAN appliance, that intercepts the data and controls access to the virtual pool of storage that it manages. Out-of-band SAN management is usually a hybrid SAN-LAN configuration where control information is sent over the LAN and data travels over the SAN.
HP's SAN Manager LM and Compaq's recently announced VersaStor (InfoStor, July, p. 1) are examples of storage pooling technology based on LUN manipulation with out-of-band management. Tivoli's SANergy, also an out-of-band approach, uses a server as a metadata controller to authorize and track shared file access. Another twist on the metadata control methodology comes from StoreAge, which implements pooling with a combination of its Metadata Center appliance and Volume Drivers.
When the virtualization layer is placed in the data path, it is usually in the form of a sort of SAN operating system that provides storage domain services to heterogeneous application servers on the SAN (see "Software-centric SAN appliances," p.28). A SAN appliance typically packages this storage domain server software with a server, sometimes with switches and disk subsystems.
Storage domain server software varies in implementation in terms of where virtualization lies in the SAN appliance's stack. A number of turnkey SAN appliances available from vendors such as DataDirect Networks and StorageApps place storage control in the data path. Likewise, software-oriented, in-band virtualization solutions are being offered by vendors such as Veritas Software and DataCore Software.
The Veritas V3 Initiative proposes an access layer, now available as SANPoint Control, a virtualization layer in the form of Veritas Volume Manager, and a native file system built from the ground up. The access layer links information between hardware devices employing standard protocols and APIs, and presents it under a uniform API to storage management and network management applications. The V3 Storage Appliance provides services in conjunction with Veritas' Volume Manager so that hosts can interact with a virtual disk image.
Major OEMs, including Sun, Compaq, and others, are expected to offer V3-based storage appliances by the end of this year.
DataCore Software has taken a slightly different approach to storage domain server software by adding extensions to Windows NT. DataCore's SANsymphony software runs at the application level, and supports a heterogeneous environment of servers and storage subsystems. Operators can interact with the disk image by using standard NT tools, and can perform backups from multiple servers without requiring agent software for sharing a backup device. DataCore's SANsymphony Network Edition will add the ability for multiple storage domain servers to collaborate in high-availability environments. (SAN-symphony is resold in SAN appliance bundles from vendors such as Gadzoox Networks and TrueSAN Networks.)
StorageApps sells a bundled storage appliance, dubbed SANlink, that includes SANSuite applications and SAN.OS base code that is layered on Windows NT. SANlink is an in-band approach that provides storage virtualization, security (including LUN masking), data mirroring (asynchronous or synchronous over Fibre Channel or IP), and point-in-time imaging (or snapshot capability).
The in-band or out-of-band nature of SAN management will determine the hooks between storage virtualization software and device management, as well as how a virtualization methodology interfaces to the network/system management tier. With combination LAN-SAN sharing scenarios, applications are fundamentally aware of the LAN, and application-driven resource sharing involves interfacing with LUN masking or metadata tables.
In the case of virtualization approaches based on SAN operating systems or storage domain server architectures, network management frameworks must treat the storage server as a new type of network domain, and therefore must become "aware" of how they interact with the storage devices themselves, as well as the applications that need to access the virtualized storage.
Storage management network protocol standards are rapidly evolving, and numerous APIs are emerging from all of the storage management software vendors. As SANs evolve, they will become more and more integral to overall enterprise IT management, with increasing automation in terms of how business policies shape the way storage is used in an enterprise.
Even today, the choices and combinations of software products are plentiful. With a profusion of open interfaces to network management platforms, users can implement SAN storage management via a software suite under the umbrella of their IT management infrastructure, or they can opt for best-of-breed software products.
Harriett Bennett is a freelance writer based in Kirkland, WA.
Software-centric SAN appliances
SAN appliances, also called storage domain servers, that are built with a software-dominant approach present virtual disk images to application hosts on the SAN, which receive their data through the appliance. Using a standard platform (such as Solaris in the case of Veritas, or Windows NT with DataCore and StorageApps), a storage domain server is typically configured with a volume manager, access services, and sometimes a native file system and other storage management tools. Multiple heterogeneous hosts interacting with the appliance share this virtual image, and all storage on the SAN is managed centrally.
Unlike LUN masking or metadata control schemes for data and file sharing, a storage domain server does not require software for each server on the SAN. Rather than coordinating masking or metadata tables over the LAN, all requests for storage are made to the SAN appliance, which intercepts them along the storage-application data path.
SAN appliance software typically provides volume management with drag-and-drop allocation, security and authorization services, point-in-time snapshots of logical volume views, and interfaces or tools for device configuration and monitoring. The volume manager handles mirroring between applications and supports multiple RAID levels (caching algorithms) for the virtual disk. Other capabilities may include remote mirroring and multi-pathing.
As network nodes, SAN appliances can be clustered to increase aggregate I/O bandwidth, with facilities available for load optimization. Collaborating SAN appliances can provide the architecture for N+1 redundancy in high- availability environments.
Having a storage domain server or SAN appliance in the data path raises the question of throughput degradation. This can be alleviated with a caching engine in the server. Caching engines make it possible for JBOD throughput to approach or exceed RAID speeds, which offers the advantage of lowering costs by substituting JBOD for RAID in many cases.
Given that software-dominant appliances are based on standard server platforms, the caching engine takes advantage of the server's memory (versus add-on hardware caching devices); price/performance advantages come from the use of commodotized hardware. With software- dominant SAN appliances, scaling for capacity, performance, and availability is in large part determined by the selection of CPU, memory, and I/O options on the server platform.
Storage management applications such as LAN-free backup work in a new way with SAN appliances. A point-in-time snapshot of volume images can be backed up to a shared secondary storage device, sometimes without the need for client software. Add to that the potential for server-less backup, with data moving directly between devices under control of the SAN appliance. Disaster recovery will be further automated with the advent of remote mirroring and protocol adaptation, such as ATM, which will enable greater connection distances to off-site facilities.
Implementing a virtualization layer with a software- oriented storage domain server provides a network-centric SAN architecture with network scalability and redundancy attributes. As SANs progress in complexity beyond islands of virtual storage to globally managed enterprise resources, they will need to behave on a more hierarchical basis, where groups of resources are created based on enterprise application attributes, including quality of service, security, accounting, and quotas.
Looking to the future, virtualization will evolve beyond server-based volumes and network-based logical volumes to a scheme where the elements of networked storage are created and managed by automated policies. Meanwhile, the building blocks exist today to create storage domains that centralize storage management, virtualize legacy and newer storage products, support heterogeneous server environments, and use the storage network for high availability