D-Link xStack Storage DSN-4000 Series, Руководство пользователя программного обеспечения

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4 Chapter 1 Introduction
Table 1-1. Types of Storage Pools
Storage Pool Usage
Available Pool Disk drives available for use, but with no data stored on them at this time. A
drive in the Base Pool will be used in the creation of a new Volume any time it is
required. That drive is automatically moved to the Base Pool at that time with no
manual interaction.
Base Pool Disk drives currently being used to hold Volume data or ready to be used to hold
volume data.
Spare Pool A drive that can only be used in case of a failure of a drive in the Base Pool. A
drive becomes a Spare only when a customer administrator so designates.
Unusable Pool Two types of drives appear in the Unusable Pool:
Drives not available for use either because they have already failed and have
not been removed from the enclosure
Drive inserted into the xStack Storage system that were previously used by an
xStack Storage system. Such a drive can be Initialized by the Administrator to
make the drive available for use (which automatically moves the drive to the
Available Pool)
When a new system is installed, all new drives are placed in the Available Pool . The drives
remain in the Available Pool until they are needed for use in a volume.
1.4 Volumes
A volume is a set of blocks of storage that are organized and presented for use by a
customer’s server (an iSCSI initiator node). Every volume must be associated with a storage
pool, which limits the drives that can be used to hold data for that Volume (only drives in
that pool can be used for this volume). Only drives in the Base Pool can be used for volumes.
The iSCSI initiator node sees the volume as a contiguous series of numbered blocks in the
same way that it would see the storage space on a single disk drive. The xStack Storage
system constructs a volume from extents, where each extent is a block of storage from a
single drive. A volume typically consists of extents from several drives. A volume of
n blocks
is shown in Figure 1-2.
Volume
Extent 1
.
.
.
Extent x
0
n-1
Figure 1-2. Internal Structure of a Volume
Volumes can be organized in several ways (see Table 1-2)