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SEP sesam backup is a process by which file system and application data specified by a backup task is copied and stored to save sets on backup media.
SEP sesam supports heterogeneous computing environments (Windows, UNIX, VMS or NetWare) and provides preset task types, such as ordinary file system backup (type Path), Exchange, MySQL, SAP HANA, etc., as well as task types for virtual environments enabling image-level backups and single-file restore.
Backed up data on save sets is preserved according to their retention time. Data can be migrated, deduplicated and replicated in order to provide fast and reliable restore. Note that standard backup does not prepare for disaster recovery. Such recovery requires special preparation and configuration with SEP sesam disaster recovery solutions: Bare Metal Recovery Linux, Bare Metal Recovery MS Windows and SEP sesam self-recovery.
SEP sesam provides four different backup levels: full, differential, incremental and copy. The backup level is specified when creating a backup event in the Main Selection -> Scheduling -> Schedules -> New backup event. The following backup levels are available:
A FULL backup always copies all data specified by the backup task, regardless of whether it has been changed or not. A save set created as FULL is the basic save set for subsequent DIFF or INCR save sets. While the backup time of a full backup can be significant, restore is fast and simple since only one backup save set is required. Information about the backup status is stored in the SEP sesam database. Note that the archive bits are not deleted on Windows systems. If you want to force-reset of the archive bits, you can enter the command -o clear_archive in the backup options.
A DIFF (differential) backup saves only data which was created or changed after the last FULL save set had been created (of the same task). A differential backup is faster than a full backup, however, to restore the whole data source, first the save set of the full backup has to be restored followed by restore of the DIFF save set. For this, SEP sesam provides generation restore that enables browsing for and selecting for restore all generations of backed up files since the last full backup.
An INCR (incremental) backup saves only data that which was created or changed after the last backup (FULL, DIFF or INCR) of the same task. This is the fastest backup method and requires the least storage space. Restoring from incremental backups is the slowest, because it requires all related save sets to be copied back – the save set of the last full backup as well as all INC backups. You should consider the advantages of time and resources when planning your backup strategy. A combination of FULL backups stored to tape drives, and DIFF or INC backups stored to virtual disk media is a common method.
A COPY backup is a full backup that has no influence on following differential (DIFF) or incremental (INCR) backups. For the treatment of archive bits, see FULL backup above. COPY backup is usually used for additional full backups, e.g., monthly backups, or backups for archiving, i.e. removal from storage.
|In case no initial FULL backup exists, differential (DIFF) or incremental (INCR) backups are automatically performed as FULL backups.|
The standard backup procedure applies to file systems and application data and may differ from the backup procedures for SEP sesam extensions, which might involve additional tasks or include other options. As special methods are used to back up such data, make sure to use the backup procedure specific to the data you want to back up. For details on supported extensions, their features and backup procedures, see SEP sesam Extensions and the SEP sesam OS and Database Support Matrix.
The standard backup procedure involves the following steps:
- Creating a backup task by selecting the data to be backed up
- Creating a backup schedule by specifying when you want to back up your data
- Creating a backup event by selecting where to back up your data to and how
For details, see Standard Backup Procedure.
SEP sesam introduces a powerful scheduling service called SEPuler that constantly checks for backup, restore and other predefined tasks scheduled for execution. When such tasks are found, SEPuler initiates the execution of the event. To prevent possible tasks conflicts and efficiently manage tasks in execution queue, SEP sesam uses the event priorities.
Once the SEP sesam environment has been configured and backup tasks for clients have been created, backups can be scheduled to run automatically. The schedules are comprehensive and flexible and can be created for any kind of event. For example, a daily schedule can be created for a number of events or several schedules (e.g., weekly full, daily incremental) can be configured for the same data protection. Available schedules are daily, weekly, monthly, yearly and custom. A schedule must have at least one event assigned to it.
SEP sesam supports parallel i.e. simultaneous backup of multiple data sources onto one drive. This is called Sesam Multiplex Stream (SMS). It offers up to 124 channels for a single drive. Each of 124 channels can serve one backup source.
Data of the different streams are distributed into packets, each packet is supplied with an identification mark and copied to the backup media. The data of a certain stream is not contiguously positioned on the media, but interrupted by packets of other streams. The identification marker of the packets enables SMS to restore the initial stream during reading.
Furthermore, SMS is able to split save sets across several media that still have some free space left (specified by media properties parameter EOM – End of Media).
The maximum number of parallel streams that can be used during backup to the backup drive is specified under the Drive properties by parameter Max. channels. For details, see Drives. Note that the number of available data streams depends on the type of Server license, e.g., ONE provides 1 backup stream, Standard provides 5 backup streams etc. For details on licenses, see List of Licenses.
SEP sesam provides data encryption types on different levels: software-based encryption for save sets (explained below, set in the backup task), hardware-based LTO encryption for LTO tape drives (done on a media pool level), and Si3 encryption for Si3 deduplication store (set in the Si3 deduplication store properties). For details on the latter two, see LTO Encryption and Encrypting Si3 Deduplication Store.
SEP sesam encryption for save sets can be enabled in the backup task properties under the tab Encryption and compression for each backup task. For details, see Setting Encryption.
Backup with VSS on Windows
Microsoft Volume Shadow Copy Service (VSS) is a Windows service for backing up running applications. VSS coordinates with other VSS-aware applications and services, and creates a shadow copy or snapshot of data for backup purposes. VSS uses a copy-on-write snapshot, allocating a small temporary storage space for it. Once the snapshot is completed, the temporary storage space is freed up again.
Backup with VSS is enabled by default for file system task type Path. All other task types, for example System state, use the required VSS writer by default. For details on SEP sesam VSS, how to activate/deactivate VSS and exclude a VSS writer from backup manually, see SEP sesam Volume Shadow Copy Service (VSS) for Windows.
Starting with version 4.4.3., SEP sesam enables you to protect and manage your storage file servers by providing support for Network Data Management Protocol. NDMP is a common protocol for backing up and restoring data on storage devices that do not support installation of a backup agent. It ensures interoperability between NAS file servers and SEP sesam, and is used as an interface that enables SEP sesam to backup various NAS appliances and copy this data to a SEP sesam Server or Remote Device Server. SEP sesam supports version 4 of the NDMP protocol.
HSM-aware backup for Windows
Hierarchical Storage Management (HSM) is a method for reducing the costs of data storage and facilitating data management tasks. Starting with SEP sesam version 4.4.2, HSM-aware backup for Windows comes as an integral part of the SEP sesam package. It provides efficient backup of data on Windows systems that is managed by HSM. SEP sesam as an HSM-aware solution recognises the reparse tags in stub files and does not trigger a recall of the original files, but performs a backup of the placeholder files without retrieving their contents. For more details, see HSM-aware Backup for Windows.
Support for NTFS alternate data streams (ADS) for Windows
From SEP sesam version 4.4.3, ADS are backed up by default when backing up a NTFS file system. They are automatically restored to any ADS-aware system. ADS are backed up by default, but can be excluded from backup by using a special option in the backup task properties.
Alternate data streams are a unique data-hiding feature of NTFS file systems. A file in NTFS consists of the unnamed data stream where the data is actually contained, and of alternate data streams that can store additional metadata. Applications may use ADS for storing file attributes. For details, see Support for NTFS alternate data streams (ADS) for Windows.