This appendix is intended to provide an overview of some of the higher level storage management products available. The products will be compared in terms of function and positioning.
The main areas in which higher level tools provide enhanced function are:
The provision of mechanisms to define when information should be backed up, archived or migrated, and what information should be selected. This allows the defined operations to be scheduled as required without the need for operator intervention.
The ability to create copies of a client system's vital data, so that in the event of a failure, the client can be restored to the same state that it was at the time of the last backup.
The ability to free up space at the client system by moving or archiving infrequently accessed information from the client to the archive storage space (usually at a server machine). If the information is required again, it can be retrieved from the archive.
The ability to structure the storage subsystems in such a way that elements of the subsystem are used in the most efficient fashion. For example, frequently accessed information, or information requiring high performance access should be stored in fast storage (usually disk). Information that is less frequently accessed should be moved to less expensive, lower performance, higher capacity media such as optical; this should happen automatically if possible, thereby freeing up space in the much in demand fast storage. If the second level of storage (that used by the first movement, or migration) of information becomes full, or for information that is accessed even more rarely, a third level could be defined of even higher capacity, cheaper, slower media, such as tape.
Levels in the hierarchy should also be accessible for specific purposes; for example, backups, or long term archives would be best stored in the tape level.
A mechanism by which disk space on a client can be utilized more efficiently. This is usually implemented by using the client disk as a cache, and maintaining the full information space at a server. When data is requested by an application on the client, it can be transparently copied to the client cache - clients see the cache to be as large as the information space at the server.
This can be used in conjunction with the capabilities mentioned in the previous points. The server information space can be treated as a level in a storage hierarchy, thereby increasing efficiency further. The space can also be backed up more easily.
The facility to manage the above capabilities from a central point, thereby minimizing the effort, and maximizing the efficiency.
Provision of ergonomic interfaces to both the server and client functions. For example, the ability to define backup and restore policies for every client system in a network centrally, through a graphical user interface; from the client point of view, being able to simply specify the required files for backup/restore or archive/retrieve, again through a graphical user interface, and have the requests automatically processed.
The range of operating systems and hardware platforms across which the higher level application can operate.
The tools discussed below will be compared against the above points to enable a reasonable comparison to be drawn.
Other points for consideration include:
Consideration of access security from clients to the server, and from any administrative components.
Consideration of the amount of time taken for backups or archive; usually related to the performance of the physical devices supported, the network protocols used, and whether concurrency is supported (multiple simultaneous client access).
Relating to the range of devices supported by the product, and their capabilities.
What range of client support is available. Does the product support environments ranging from small workgroups of common machines through to large, complex networks of multiple system types?
Provision of an Application Programming Interface to allow other products to make use of the services provided by the storage management tool. Allowing applications such as databases for example to utilize storage managers to automatically backup information.
ADSM is a client/server based hierarchical storage manager that allows for centrally managed and scheduled, automated, network based backup and archive function. Both server and client components are supported across a wide range of platforms. An administrator component provides for local or remote configuration and management of the operation of ADSM via a command line or graphical user interface.
ADSM provides a scheduling function that allows backups/restores and archive/retrieves to be executed automatically by the server at the requested times. This means that the client systems can be backed up overnight for example, or at times when impact on user productivity is minimal.
Clients can have all of their vital data backed up across a network to the server storage automatically on a regular basis. Users can also issue manual backup requests for directory trees, directories, or even individual files if required. In the event of loss of data, the backed up information can be restored (in the event of complete loss for example) or requested directories or files can be individually restored at user request.
ADSM also supports a large range of backup methods including full, incremental and selective, as well as policy based.
In the same way as backups and restores are implemented, archival and retrieval operations can be arranged. In the case of both backup and archive (if authorized), users can select the storage pool to which their backup/archive is directed.
Storage at the server is organized into storage pools of similar device types (disk, tape, and optical). These pools can be linked into a hierarchy if required, and criteria set for movement (migration) of information down the hierarchy. For example the top level of a hierarchy may be comprised of a disk pool, the second layer optical, and the third tape. If the first pool approaches a preset capacity limit, ADSM will automatically migrate information to the next pool down to free up space. If a migrated file is requested, it is automatically copied from its location in the hierarchy to the requesting client.
Client disk space utilization is not managed by ADSM at the current release, although a future release will provide this function.
All of the functions provided by the server and all of the data storage is maintained centrally, and thus easily managed. An administrative component provides the capability to monitor and configure ADSM, either locally at the server, or remotely from any supported administration client machine in the network.
ADSM provides command line and graphical user interfaces for both the administrative and client components. This maximizes ease of use, as menus present the available options, and icons depict the current configurations. The learning curve is consequently shorter, and productivity higher. Availability of the graphical user interface is dependant upon the platform; some platforms only support the command line interface for example.
The server component is supported under AIX, OS/2*, OS/400*, MVS and VM. ADSM for VSE is announced, and there is a statement of direction for ADSM/HP and ADSM/SUN.
The client component is supported under DOS, Microsoft Windows, OS/2, AIX, HP/UX**, SunOS**, DEC ULTRIX**, SCO 386 UNIX**, MAC, and Novell Netware**.
The administrative component is supported on DOS, Microsoft Windows, OS/2, AIX, HP/UX, SunOS, DEC ULTRIX, SCO 386 UNIX, TSO, and CMS.
FSF/6000 is a client/server based storage manager that provides automated disk space management services to clients. Client disk space is managed by utilizing administrator defined policies to remove files from the client disk to maintain free space. The removed files are actually copied to the server and are transparently returned when required.
FSF maintains a designated area of the clients disk as cache. Information created within this cache can be automatically maintained by FSF/6000. Data can be migrated on the basis of size, time since last access, or it can be pinned into the cache if it is regularly accessed. Information requested that has been removed from the cache to free up space is automatically and transparently copied back to the cache.
FSF does not provide this function.
FSF does not provide this function.
FSF does not provide this function, although it can be configured to work with ADSM, with the FSF server using an ADSM storage pool as its client file space (location to maintain copies of client information). In this case, ADSM could automatically migrate information from the filespace when it approached a capacity threshold.
As outlined in the section on automation, FSF manages disk space on behalf of clients. It does this by maintaining remote copies of any information created in the managed area of the clients storage at the server, either using NFS, or ADSM to do so (see Network File System for a brief explanation of NFS). When space becomes critical in the cache, local copies of the information are deleted using size or last access as selection criteria, thereby maintaining free space. For performance reasons, very frequently accessed files can be pinned locally (this prevents the file from being deleted, although a copy is always kept at the server).
Client data is usually maintained at the FSF server location, but could be located on an NFS mounted directory from another machine. In the sense that all configuration must be done at the server though, FSF is centrally maintained, but only from the server.
Configuration and management of FSF is performed via SMIT menus. Actual usage should be transparent.
FSF/6000 is only supported under AIX.
Legato Networker** is a client/server based product that provides automated backup services in a networked environment. Networker client and server components are supported across a range of platforms.
Backup operations can be scheduled at the server to take place when required.
Legato Networker provides backup/restore services to clients in a networked environment. Up to 12 different backup types may be scheduled:
All files at the client are backed up
All files that have changed since a previous full (level 0) backup or since a previous lower level backup. For example, if a level 4 backup is scheduled for Monday night, then only files that have changed since the last level 0, 1, 2, or 3 backup will be backed up.
All files that have changed since last backup, regardless of level, are backed up.
This level allows a backup to be skipped at a given time; for example, if a backup from client is scheduled for Saturday night, using this option will prevent that backup from occurring.
Legato Networker does not provide this function.
Legato Networker performs backups directly to tape or optical devices. The concept of a hierarchy is not defined.
Legato Networker does not provide this function.
A command line and graphical user interface based administrative component is provided that allows Networker to be configured, managed, and monitored from any client in the network.
Initial setup and configuration of Legato is manual, however once setup, the graphical administrative component can be used to manage the product. There is no requirement for client interaction, so no interface is provided to the client components; the code for clients is accessed via NFS, or locally on disk, setup is manual.
The server component is supported under AIX.
Client support is provided for AIX, Novell Netware, DOS, SunOS, Sony** NEW-OS, HP/UX, DEC ULTRIX, RISC/os, and SGI IRIX.
UniTree** is a client/server based hierarchical storage manager that provides centrally managed, automated hierarchical storage management in a networked environment.
Similarly to FSF/6000, UniTree will automatically perform migration of client data within the UniTree file system down the defined hierarchy of storage devices, based on configurable criteria. When data is requested by a client, UniTree can transparently retrieve the information from the lower level in the hierarchy, and make it available to the requesting client.
UniTree does not provide backup/restore services for clients.
As with FSF/6000, UniTree provides remote access to a managed file system for clients. The file system space is maintained through automatic archival of files based upon configurable criteria (such as access frequency and size). When data is required by a client, it is transparently recovered from its place in the hierarchy.
UniTree defines a hierarchy of storage devices, similar to ADSM, with faster, more expensive media such as disk at the top, moving down to slower, larger capacity, cheaper media at the bottom. Information is migrated down the hierarchy as described in the previous two sections thus ensuring that the most frequently accessed information is available on the fastest devices.
Disk space utilization is maximized at the server, as automatic archival through migration ensures that there is always free space available. This does of course depend upon there being enough free space lower down the hierarchy for migration to succeed.
The storage hierarchy is administered at the server, though all configuration and management is via SMIT. Each client utilizes the services provided via NFS (see Network File System for a brief description of NFS), or FTP.
Server management and administration is achieved via SMIT, and is therefore performed on the server machine. Client access to the UniTree file systems is via NFS or FTP, and should be transparent to the user. Likewise, migration and archival/retrieval of information is performed automatically and should be transparent.
The server is supported under AIX.
Client platforms supported with the AIX server include SUN, DEC, SGI, HP and AT&T**.