Volumes - D-Link DSN-5410-10 - xStack Storage Area Network Array Hard Drive Software Manual

Storage Pool
Available Pool
Base Pool
Spare Pool
Unusable 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.
Volumes can be organized in several ways (see Table 1-2)
4 Chapter 1 Introduction
Table 1-1. Types of Storage Pools
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.
Disk drives currently being used to hold Volume data or ready to be used to hold
volume data.
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.
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)
0
Extent 1
.
.
.
Extent x
n-1
Volume
Figure 1-2. Internal Structure of a Volume
Usage