Glossary

Automated Storage Tiering (ETERNUS DX/AF)

Performance-dependent use of the capacity of storage systems by automatically controlled data migration. -> Flexible Tier Pool. -> Flexible Tier Volume. -> tiering policies.

cascaded remote copy

-> remote copy configuration

channel adapter (CA)

-> channel adapter

channel adapter

The channel adapters process input/output requests from the server end and control access to the storage system cache.

clone pair, clone pubset, clone session, clone unit

A clone unit is the copy of an original unit at a particular time (“Point-in-Time copy”). The local replication functions of the storage systems create this copy optionally as a complete copy or as a “snapshot”.
After they have been activated, the original unit and clone unit are split; applications can access both.
The original unit and clone unit together form a clone pair and are managed in what is known as a clone session.
If clone units exist for all original units of a pubset, these clone units together form the clone pubset.

concurrent remote copy

-> remote copy configuration

concurrent target unit

-> target unit in a concurrent -> remote copy configuration

data device

Internal devices which are configured in the Symmetrix storage system and provide storage space for storing the contents of the -> thin devices.

data striping

Distribution of the individual data blocks of a file across the access systems.

director

Channel adapter of the Symmetrix/VMAX3 systems (e.g. remote link director). The channel adapters are of different types which match the different channel types.

disaster tolerant disk system (DTDS)

The highest level of security in the new system of classification of the RAB (Raid Advisory Board). This level is attained by storage systems that are protected against data loss and failure over a wide area by means of redundant, geographically distant data recording.

disk adapter (DA)

Disk adapters control access to the physical drives. Two microprocessors per disk adapter support a total of four SCSI paths. Simultaneous data transfer is possible on two SCSI paths per disk director (one path for each side).
To ensure reliability, the disk adapters are interconnected in pairs internally.

Equivalent Copy (EC)

Replication function for ETERNUS DX/AF which offers the clone functionality.

ETERNUS DX/AF

ETERNUS DX/AF systems are high-availability storage systems of FUJITSU.

failback

Failback denotes a return to recovered resources after a failover.
In this manual this especially refers to:

• • • • • • • the return of applications from target units to source units in a remote copy configuration

            • the return to the primary storage system in a Storage Cluster

failover

In general, failover is the switching procedure from failed resources to redundant identical resources.
In this manual this especially refers to:

• • • • • • • the activation of the target units in a remote copy configuration

            • the switching to the secondary storage system in a Storage Cluster

flexible tier pool (flex pool for short)

Predefined pool for managing the -> flexible tier volumes.

flexible tier subpool (flex subpool for short)

Performance-dependent pool containing -> flexible tier volumes in the -> flexible tier pool.

flexible tier volume (flex volume for short)

Generated volumes in the -> flexible tier subpool.

gatekeeper devices

Gatekeeper devices are devices configured in the Symmetrix/VMAX3 storage systems and on the SYMAPI server for handling the SYMAPI inputs/outputs.

local storage system

The local storage system is located in the local Data Center and generally contains the source units. All I/Os are written to the source unit first.

local system

The local system is located in the local Data Center. The original processing takes place on the local system. In normal operation it sends the I/Os to the local storage system.

meta volume

A meta volume is a correctly sequenced, linked set of logical volumes. As far as the server is concerned, these comprise a single logical unit. In fact, there is a meta header volume and all other volumes are meta member volumes. With TimeFinder and SRDF actions, it is always the meta header volume that is specified; the action is carried out automatically for the meta header volume and all associated meta member volumes.
Data addressing on meta-devices can be organized in two ways:

• “Concatenated devices”: Bytes 1 to n are on the first meta-device, n+1 to 2n on the second, and so on. n is the size of a meta-device.

• "Striped devices": Data is divided into stripes of size s. Bytes 1 to s (i.e. the first stripe) are on the first meta-device, bytes s+1 to 2s on the second, and so on to the last device; the next stripe is again on the first meta-device, and so on.

POSIX semaphores

Variables which control access to a shared resource.

QuickOPC

Replication function for ETERNUS DX/AF which offers the clone functionality.

RAID0

RAID0 implements the distribution of the individual data blocks of a file (“data striping”) without data backup.

RAID1

RAID1 fully duplicates data on double the number of disks.

RAID5

RAID5 implements joint parity checking for several disk drives with distribution of the individual data blocks of a file over the disk drives (no -> data striping).
RAID5 can be configured as 3+1 or 7+1.

RAID6

RAID6 implements joint parity checking for several disk drives with distribution of the individual data blocks of a file over the disk drives. The data is then also protected when a second drive fails during a “rebuild process”. RAID6 can be configured as 6+2 or 14+2.

RAID10

RAID10 implements the distribution of the individual data blocks of a file (-> data striping) and at the same time fully duplicates the data on double the number of disks (RAID1 and RAID0).

RA groups

RA groups determine the SRDF connection between two Symmetrix/VMAX3 storage systems. A local and a remote RA group are configured in an SRDF connection. An RA group consists of two or more remote adapters. A remote adapter can be assigned to several RA groups (-> remote copy configuration). Each volume used for SRDF can be assigned to up to two RA groups (-> concurrent remote copy)).

Redundant Array of Independent Disks (RAID)

RAID refers to a technological concept for improving data availability. RAID levels RAID0 through RAID10 exist.

Remote Equivalent Copy (REC)

Function of ETERNUS DX/AF for creating (additional) copies of application data of a local storage system in other, geographically distant storage systems.

remote copy configuration

Configuration when remote replication is used: The data of a local storage system is mirrored to one or more remote storage systems. There are the following configuration variants:

• Single remote copy configuration with -> remote copy pairs

• Concurrent remote copy configuration with -> remote copy pairs which operate simultaneously (concurrently)

• Switched remote copy configuration (SAN connection)

• Cascaded remote copy configuration (cascaded replication, Symmetrix/VMAX3)

• SRDF/A configuration: Asynchronous processing mode of SRDF with cross-volume consistency.

remote copy pair

A remote copy pair consists of a source unit (original, local storage system) and a target unit (data copy, remote storage system) that are connected to each other by means of a remote link.

remote adapter (RA)

-> remote link director

remote link director

The remote link director (remote adapter, RA) is an adapter for FC channels or Gigabit Ethernet. It is used to connect the local and remote Symmetrix/VMAX3 storage systems for remote copying.

remote storage system

The remote storage system is located in the remote Data Center and generally contains the target units. If the entire local Data Center fails (local system and local storage system), the target units are released for use by the standby system.

save device

Save devices save all original data which was modified on the original unit (and also on the snap unit) in the course of a snap session

Save Pool / Snap Data Pool (SDP)

-> snap pair

SMI-S

Storage Management Initiative Specification, the standard which is defined and supported by the SNIA (Storage Networking Industry Association) for non-proprietary, uniform management of storage systems.

SnapOPC+

Name of the snap function for ETERNUS DX/AF with the option of creating and operating multiple snap sessions for one original unit.

Snap Data Volume (SDV), Snap Data Pool Volume (SDPV), Snap Data Pool Element
     (SDPE)

SnapOPC+ uses specially configured devices in the storage system, which are known as Snap Data Volumes (SDVs), as snap units. If the capacity of the SDV has been exhausted, it is provided with further capacity from a central pool (Snap Data Pool, SDP) of the storage system by one or more Snap Data Pool Elements (SDPEs) being made available.

snap pair, snap pubset, snap session, snap unit

A snap unit is the copy of an original unit at a particular time (“Point-in-Time copy”). The local replication functions of the storage systems create this copy
as a “snapshot” in accordance with the “Copy-On-First-Write strategy“: Only if data is modified is the original data concerned written beforehand into a snap save area (Save Pool / Snap Data Pool) of the storage system. The snap unit contains the references to the original data. In the case of unmodified data the references point to the original unit, in the case of modified data to the snap storage area.
After they have been activated, the original unit and snap unit are split; applications can access both.
The original unit and snap unit together form a snap pair and are managed in what is known as a snap session.
If snap units exist for all units of a pubset, these snap units together form the snap pubset.

source path

Input/output path from the local system to the -> source unit

source unit

The source unit is generally located on the local storage system. All I/Os are written to the source unit first.

standby system

The standby system is located in the remote Data Center. It takes over processing if the local system fails and normally uses the target path to the remote storage system.

Storage Cluster

The “Storage Cluster Option (SCO)” function links two ETERNUS DX/AF storage systems to a failsafe storage system, so called “Storage Cluster”.

switched remote copy

-> remote copy configuration

SYMAPI Symmetrix Application Programming Interface

Strategic interface of EMC for administering and controlling the storage systems.

Symmetrix

Symmetrix systems are “older” storage systems from EMC.

Symmetrix Remote Data Facility (SRDF)

Function of the Symmetrix SRDF enables replication to another Symmetrix/VMAX3 storage system by means of remote copy. The second, remote system can be installed at any location. Thus failure recovery functionality is provided.-> remote copy configuration

target path

Input/output path from the standby system to the -> target unit

target unit

The target unit is usually located on the remote storage system. The target unit is a copy of the source unit and is synchronized with it. In the event of a failure, the target unit receives I/Os via the target path.

thin device

Virtual volume with a large capacity. Virtual volumes occupy physical storage from a jointly used storage pool as required. -> thin pool

thin pool

Predefined pool for managing the -> thin devices.

Thinpoolavoid file

Optional file thinpoolavoid in POSIX directory var/shcosd/config in which a list of thin pools can be specified which are not to be monitored by SHC-OSD when THIN-POOL-MONITORING=BY-AVOID-FILE or FLEX-POOL-MONITORING=BY-AVOID-FILE is specified in the SHC-OSD parameter file.

thin provisioning

Efficient use of the capacity of storage systems by virtual volumes with a large capacity. -> Thin Provisioned Volume (TPV) -> virtual provisioning.

Thin Provisioned Pool (TPP, thin pool for short)

Predefined pool (ETERNUS DX/AF) of physical disks to provide the physical storage space for -> Thin Provisioned Volumes (TPVs).

Thin Provisioned Volume (TPV)

Virtual volume (ETERNUS DX/AF) with a large capacity. Virtual volumes
occupy physical storage from a jointly used storage pool as required. -> thin pool (TPP).

tiering policies

Rules for -> Automated Storage Tiering. -> Flexible Tier Pool.

TimeFinder, TimeFinder/Clone, TimeFinder/Snap (Symmetrix)

Product family of EMC whose functions permit (additional) copies of the application data to be created within a Symmetrix storage system. TimeFinder consists of autonomous products:
TimeFinder/Clone creates, activates and reconstructs -> clone pairs. TimeFinder/Snap creates, activates and reconstructs -> snap pairs.

TimeFinder SnapVX (VMAX3)

Product of EMC whose functions permit (additional) copies of the application data to be created within a VMAX3 storage system.
TimeFinder SnapVX creates, activates and reconstructs -> snap pairs.
TimeFinder SnapVX emulates TimeFinder/Clone for VMAX3.

virtual provisioning

Efficient use of the capacity of Symmetrix/VMAX3 storage systems by virtual volumes with a large capacity. -> thin device. -> thin provisioning (generic term).

virtual device

The virtual device of the storage system is the -> snap unit, which can be accessed from the server.