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© 2009 IBM Corporation Statements of IBM future plans and directions are provided for information purposes only. Plans and direction are subject to change.

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Presentation on theme: "© 2009 IBM Corporation Statements of IBM future plans and directions are provided for information purposes only. Plans and direction are subject to change."— Presentation transcript:

1 © 2009 IBM Corporation Statements of IBM future plans and directions are provided for information purposes only. Plans and direction are subject to change without notice. Components of a DS Storage Solution Ryan Leonard Storage and Solutions Architect

2 System Storage February 2009 © 2009 IBM Corporation Agenda  Components of a DS3/4/5000 storage solution –Physical vs. logical  RAID levels

3 System Storage February 2009 © 2009 IBM Corporation 3 main physical components  Storage Server –Contains RAID controller(s) –Power supplies, fan assemblies, etc.  Expansion enclosures –Contains ESMs –Power supplies, fan assemblies, etc.  Disks –Where the data is actually stored

4 System Storage February 2009 © 2009 IBM Corporation Storage Server  Primary computational element –Generally composed of two RAID controllers –May be a discrete entity DS4800, DS5000 – or integrated with disks DS3000, DS4700  What is a RAID controller? –Handles all I/O operations to the underlying media –Provides data protection via RAID configuration –Basic management interface as well as premium features  The type of Storage Server determines the product model (e.g. DS3200 or DS5300) Cache memory controller with RPA Host interface Drive interface Cache

5 System Storage February 2009 © 2009 IBM Corporation Expansion enclosures  Provides housing for individual disk drives  Connects to the controller via ESMs (environmental service modules)  Two major types of current expansion enclosures –SAS-based EXP3000 for DS3000 products –FC-based EXP810 / EXP5000 for DS4000 / DS5000 products

6 System Storage February 2009 © 2009 IBM Corporation Disks  DS4000 and DS5000 supports FC and SATA disks –May be intermixed within an expansion enclosure  DS3000 supports SAS and SATA disks –May be intermixed within an expansion enclosure

7 System Storage February 2009 © 2009 IBM Corporation FC? SAS? SATA?  FC and SAS drives are very similar in terms of performance and reliability  SATA have larger capacities and a better price per GB, however- –They are significantly ‘slower’ than either FC or SATA disks –The may have a lower designed duty cycle  For database or other I/O oriented applications, SATA drives are probably not a good fit –Slower rotational speed –Higher access time –Somewhat limited command queuing  Sequential large block read performance can be similar

8 System Storage February 2009 © 2009 IBM Corporation Logical components of a storage system  Arrays and logical drives –More commonly known as RAID sets and LUNs  An array is a group of disks which are grouped together using a distinct protection scheme –RAID 0, 1, 3, 5, 10, or 6 * –Group size may be either 30 drives for RAID 3, 5, and 6 or system max. for RAID 0 and 10 –The host/server has no knowledge of the underlying RAID configuration  A logical drive is an element of the array –A given logical drive can be from 10MB to the entire size of the array it is contained in –You can have multiple logical drives per array –The logical drive is the entity that is mapped to a given server –To the server, the logical drive appears as a direct-attached SCSI disk of the size determined by the user –Logical drives on the same array may be mapped to different servers (and have very different properties) * RAID 6 is supported on the DS3200, DS3300, DS3400, DS4700, DS5100, and DS5300 Array of 3 drives RAID 5, 2+P Logical drive 1 – x GB Logical drive 2 – x GB

9 System Storage February 2009 © 2009 IBM Corporation RAID = Redundant Array of Inexpensive Disks  Why use RAID? –Enhanced performance –Access to data (disks are mechanical device and will fail!)  An array must have an associated RAID level –For DS3/4/5000 products RAID 0, 1, 3, 5, 10, 6 RAID 0 – from a single drive to all of the drives in the system RAID 1 – two drives RAID 3 – from 3 drives to 30 drives RAID 5 – from 3 drives to 30 drives RAID 10 – from 4 drives to all of the drives in the system RAID 6 – from 5 drives to 30 drives –Physical location of drive(s) is not relevant in the DS3/4/5000 products –Same type of drives must be in a given array (i.e. FC, SAS, SATA)  What’s the difference?

10 System Storage February 2009 © 2009 IBM Corporation RAID 0  Simple striping  Not actually redundant –If a drive fails, there is no ability to recover the failed data  Due to lack of redundancy, very infrequently used –Temp. space  Useable capacity = raw capacity Drive 1Drive 2Drive 3Drive 4Drive 5 RAID 0 Array File A A1A2A3A4A5

11 System Storage February 2009 © 2009 IBM Corporation RAID 1  Simple mirroring  Only allows for 2 drives maximum  Due to lack of scalability, very infrequently used –Small write intensive items, like database log files  Useable capacity = ½ raw capacity Drive 1Drive 2 RAID 1 Array File A AA’

12 System Storage February 2009 © 2009 IBM Corporation RAID 10  Mirroring and striping  For DS3/4/5000, a specialized subset of RAID 1 containing more than 2 drives  Must be even number of drives  Very common usage –Typically applications that have high amounts of write activity or perform high amounts of random I/Os  Useable capacity = ½ raw capacity Drive 1Drive 2 RAID 10 Array File A A1A1’ Drive 3Drive 4 A2A2’

13 System Storage February 2009 © 2009 IBM Corporation What is parity?  RAID levels 3, 5, and 6 all use ‘parity’ to allow for redundancy of information –Parity generated at the hardware level (remember RPA?) using a mathematical XOR –XOR can be generically thought of as ‘either A or B, but not both’  Consider the following (grossly simplified) example- 10 Block of data #1 (data A) Block of data #2 (data B) 1 Block of data #3 (parity)

14 System Storage February 2009 © 2009 IBM Corporation RAID 3  Striping with parity information  Generally used for streaming or sequential workloads  Parity is rotating  Due to similarity to RAID 5, RAID 5 is typically used instead  Useable capacity = (raw capacity – 1 disk for parity) Drive 1Drive 2Drive 3Drive 4Drive 5 RAID 3 Array File A A1A2A3A4Ap

15 System Storage February 2009 © 2009 IBM Corporation RAID 5  Striping with parity information  Most widely used RAID type  Parity is rotating  Useable capacity = (raw capacity – 1 disk for parity) Drive 1Drive 2Drive 3Drive 4Drive 5 RAID 5 Array File A A1A2A3A4Ap

16 System Storage February 2009 © 2009 IBM Corporation RAID 6  Striping with parity plus an add’l separately calculated protection element (q)  Generally used for environments with SATA drives  Can sustain 2 drive failures in the group  Parity and q value are rotating  Useable capacity = (raw capacity – 2 disks for parity information) Drive 1Drive 2Drive 3Drive 4Drive 5 RAID 6 Array File A A1A2A3ApAq

17 System Storage February 2009 © 2009 IBM Corporation Summary Storage Server Drive enclosure DrivesArrayLogical drive


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