存储中卷组的基本概念

Now, we have a Parity Group with Free Space available!
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Using Free Space
To use Free Space for data storage, four tasks must be performed.
1. Define an Emulation Type for the Parity Group, thereby creating Volumes - virtual storage devices/disks. 2. Assign Volume information to the newly created Volumes to uniquely identify the devices. 3. Map the Volumes to a CHIP* port. 4. Connect a server to the CHIP port.
RAID Control
A Group of Disks
A RAID Group
XP Specific Concept: XP Array Parity Group
From a XP Array Marketing Array Group of independent disks to an XP Array Parity Group
*CHIP means Client Host Interface Processor (analogous to an HBA on a server)
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Emulation Types
Normal disk drives come in different sizes; XP Arrays offer customers a set of predefined ―disk‖ sizes.
• Together, the CU and the LDEV number uniquely identify a LUN in an XP Array disk Example: for CU=01 & LDEV=2a, the Volume = 01:2a
Assigning Volume Information
– CU is a carry over from the old mainframe days where disk storage was addressed with an eight bit word)
• The LDEV (Logical Device) number is an arbitrary number from 0 – 255.
RAID Concept – the Cost
For RAID 1, the Parity Data uses 50% of the total disk space; data is either mirrored, or there are two copies of the data. For RAID 5, the Parity Data uses 1/(# of disks) of total disk space and parity data is interleaved among all disks
Only one Emulation Type may be assigned to a Parity Group.
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Emulation Types & Normal Volumes
Normal Volumes are of a fixed size. Example: OPEN-3 Volumes are 2.347 MBytes in size. When a Parity Group’s Free Space is partitioned during the Emulation Type Configuration task, any remaining space left over is still Free Space. Remember, Free Space is not usable unless configured.
These predefined ―disk‖ sizes are known as Emulation Types.
An Emulation Type must be defined for a Parity Group, thereby partitioning the Free Space into predefined Open-Volume sizes.
• Two devices on a host with the same XP Array Volume (CU:LDEV) number are really alternate paths to the same Volume.
Parity Group
Emulation Type Defined
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Normal Volumes & Free Space
Example: Let’s say I have the following –
• An Emulation Type with a defined size of 3.0 Gbytes • A Parity Group with 32 Gbytes of Free Space before setting the Emulation Type
Initial Free Space / Emulation Size per a Volume = # Volumes (32 Gbytes of Free Space ) / (3.0 Gbytes per a Volume) = ??? 32/3.0 = 10 Volumes Created
Normal Volumes & Free Space
Using Available Space
First, assign an Emulation Type to the Parity Group, such as OPEN – E.
OPEN-E
Define Emulation Type
OPEN-E OPEN-E OPEN-E OPEN-E
Free Space
OPEN-E
OPEN-E OPEN-E OPEN-E OPEN-E Free Space
Assign Volume Numbers
0:0 2:0 1:0 1:1 2:1
Free Space
Emulation Байду номын сангаасype Defined
Volume Assignments
LUN Mapping?
“LUN Mapping‖ should really be called ―Volume Mapping‖, since that’s what it is
After specifying an Emulation Type for a Parity Group, next assign Volume Numbers to the OPEN-E’s, thereby uniquely identifying the new virtual disks.
After setting the Emulation Type –
• How many Normal Volumes will be created? • How much Free Space will be left?
Normal Volumes & Free Space
Solution:
How many Normal Volumes will be created?
Mapping a Volume to a Port
An XP Volume (CU:LDEV) is visible to a server as a logical storage device (a LUN or Disk), only after being mapped to an array port that is connected to the host.
For more information: /rabguide.html /hp.html
General Concept: From Disks to RAID Group
From a group of independent disks to a RAID group
XP Array Volumes (LUNs)
Regarding the XP array, a Volume (LUN) refers to the CU:LDEV number. • The CU number defines a Control Unit and is used by the XP’s internal data structures to manage its virtual disks. One CU can contain 256 LDEV’s (
RAID Control
XP Marketing Array Group
XP Array Parity Group
Creating a Parity Group
Q. How is Free Space created?
A. By creating a Parity Group.
Process:
1. A RAID level must be defined for an XP Array Domain – this should already have been performed. 2. A Marketing Array Group of disks must be installed into the array Domain.