存储中卷组的基本概念.ppt

1、存储中卷组的基本概念,A solution,RAID Provides for highly available data despite a disk failure Provides for online reconstruction of lost data Costs space Industry standard redundancy algorithms,RAID Concept - Parity,Storage Capacity = (Disk Capacity) - (Parity Data) Parity Data is redundant information that

2、can be used for data reconstruction.,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 Fo

3、r more information: http:/www.raid-,RAID Concept:XP Array RAID Group,Think of RAID protected XP Array storage space in a logical way: RAID data is protected usable storage space users DO NOT know exactly were the data is vendors implement RAID types in different ways.,General Concept: From Disks to

4、RAID Group,From a group of independent disks to 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,XP Array Free Space,Usable space in the XP Array is found within a Parity Group and is called Free Space. Fre

5、e Space is available to the customer, but NOT in its raw form. Free Space is availalable for use AFTER the Array group has been formatted. An array may have 200 Gbytes of raw Free Space per a Parity Group that must be formatted for customer usage.,9,Creating a Parity Group,Q.How is Free Space create

6、d? A.By creating a Parity Group. Process: A RAID level must be defined for an XP Array Domain this should already have been performed. A Marketing Array Group of disks must be installed into the array Domain. Now, we have a Parity Group with Free Space available!,Sept 2004,HP Restricted,10,Using Fre

7、e Space,To use Free Space for data storage, four tasks must be performed. Define an Emulation Type for the Parity Group, thereby creating Volumes - virtual storage devices/disks. Assign Volume information to the newly created Volumes to uniquely identify the devices. Map the Volumes to a CHIP* port.

8、 Connect a server to the CHIP port. *CHIP means Client Host Interface Processor (analogous to an HBA on a server),Sept 2004,HP Restricted,11,Emulation Types,Normal disk drives come in different sizes; XP Arrays offer customers a set of predefined “disk” sizes. These predefined “disk” sizes are known

9、 as Emulation Types. An Emulation Type must be defined for a Parity Group, thereby partitioning the Free Space into predefined Open-Volume sizes. Only one Emulation Type may be assigned to a Parity Group.,Emulation Types & Normal Volumes,Normal Volumes are of a fixed size. Example: OPEN-3 Volumes ar

10、e 2.347 MBytes in size. When a Parity Groups 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.,Sept 2004,HP Restricted,13,Using Available Space,First, assign an Emulation Ty

11、pe to the Parity Group, such as OPEN E.,OPEN-E,Normal Volumes & Free Space,Example: Lets 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 After setting the Emulation Type How many Normal Volumes

12、 will be created? How much Free Space will be left?,Normal Volumes & Free Space,Solution: How many Normal Volumes will be created? 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

13、 Space,Solution: How much Free Space will be left? Initial Free Space Used Free Space = Unused Free Space (32 Gbytes of Free Space) (10 Volumes * 3.0 Gbytes per a Volume) = Unused Free Space 32 30 = 2.0 Gbytes of Free Space left,XP Array Volumes (LUNs),Regarding the XP array, a Volume (LUN) refers t

14、o the CU:LDEV number. The CU number defines a Control Unit and is used by the XPs internal data structures to manage its virtual disks. One CU can contain 256 LDEVs ( CU is a carry over from the old mainframe days where disk storage was addressed with an eight bit word) The LDEV (Logical Device) num

15、ber is an arbitrary number from 0 255. 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,After specifying an Emulation Type for a Parity Group, next assign Volume Numbers to the OPEN-Es, ther

16、eby uniquely identifying the new virtual disks.,Volume Assignments,0:0,1:0,1:1,Free Space,2:1,Assign Volume Numbers,OPEN-E,2:0,OPEN-E,LUN Mapping?,“LUN Mapping” should really be called “Volume Mapping”, since thats what it is LUN Mapping is the process of mapping a Volume to a CHIP (Client Host Inte

17、rface Processor) port for the purpose of allowing an external host to use the volumes for storage.,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. Alternate P

18、aths: A Volume mapped to more than one array port is said to have an alternate path. A Volume with multiple paths to a host, will appear to a host as multiple and separate storage devices. Two devices on a host with the same XP Array Volume (CU:LDEV) number are really alternate paths to the same Vol

19、ume.,Volume Types,Normal Volumes are sized according to the type of device being emulated (Emulation Type). Open Systems have normal volume “OPEN-*” Emulation Types, such as OPEN-3/8/9/L/E. Normal Volumes are of a fixed size. Example, OPEN-3 Volumes are 2.347 MBytes in size. Open-V volumes (Xp1024 a

20、nd XP128 only) can be specified as any requested size from 45MB up to 2TB Only one Emulation Type may be assigned to a Parity Group.,XP12000 Disk Emulations,Usable Space (space available for use by a host) Open3= 2,461,040,640 (2.4GB) Open8= 7,347,732,480 (7.3GB) Open9= 7,384,596,480 (7.4GB) OpenE=1

21、4.506 GB (14.5GB) OpenL= 33.94 GB OpenV =Variable,Open-V Volume Overview,Normal Volumes come in a predetermined “Emulation” size Some Normal Volumes are OPEN-3/8/9/E/L/M Custom Volumes are those of a “Custom Volume Size” also referred to as CVS Volumes LUSE Volumes are groupings of identical Volumes

22、 to produce a larger Volume Open-V is a new emulation type,OPEN-V Overview,OPEN-V is a new “Emulation” type applied across a parity group Initial support with FW release 21.04.04 Provides a custom Volume size without past constraints. Is an extension/combination of CVS & LUSE functionality Requires

23、CVS & LUSE products (licenses) Volume sizes from 46.8 MB 2 TB (limited) Capacity can be specified in either MB or Cylinder Is really a new process that combines CVS and LUSE Minimum Cache Memory (CM) & Shared Memory (SM) requirements must still be met Can be specified across either 4 disk or 8 disk

24、parity groups,Array configuration Addressing,LUN mapping (mapping volumes),Volume mapping Mapping a volume to one or more CHIP ports Alternate paths How to uniquely identify the XP disk seen by server?,Sept 2004,HP Restricted,27,Cannot mix disk sizes within a four disk array group Disks can only be

25、installed in sets of four identical disk Can mix RAID types on an ACP pair ex) RAID 0/1 and RAID5 groups can exist in the same ACP pair,HP XP1024 Disk and RAID Intermix Rules,Parity Group & Volumes,Carving up an Array Group into OPEN Emulations: Illustration 1,Open9,Open9,Open9,Open9,RAID5,36GB,HDD,

26、36GB,HDD,36GB,HDD,36GB,HDD,Unused Space,Open9,Open9,Array Group,Carving up an Array Group into OPEN Emulations: Illustration 2,Array Group 1-1,RAID 0/1,73GB,HDD,73GB,HDD,OpenE,OpenE,Unused Space,OpenE,HDD,HDD,73GB,73GB,Open9,Open9,Open9,Open9,73GB,HDD,73GB,HDD,Unused Space,Open9,Open9,RAID 0/1,HDD,HDD,73GB,73GB,Array Group 1-2,More On Control Unit,Control Units 32 Control Units (CU) per DKC A single CU can be combined with 256 LDEVs