The document discusses different types of storage systems including direct attached storage (DAS), network attached storage (NAS), and storage area networks (SAN). It describes DAS, where storage is directly connected and managed by a single host, and its strengths of being inexpensive and familiar, but also limitations around scalability and distance due to physical cable connections. Examples of internal and external DAS configurations are provided along with diagrams showing connections between servers, controllers, and disk drives.

1. Introduction To StorageIntroduction To Storage
Overview of the storage subsystemOverview of the storage subsystem
ISOMETRICISOMETRIC
CONSULTANCY SERVICESCONSULTANCY SERVICES

2. Storage typesStorage types
 Single Disk DriveSingle Disk Drive
 JBOD (Just Bunch Of Disk)JBOD (Just Bunch Of Disk)
 VolumeVolume
 Storage Array (RAID)Storage Array (RAID)
 DAS (Direct Attached Storage)DAS (Direct Attached Storage)
 NAS (Network Attached Storage)NAS (Network Attached Storage)
 SAN (Storage Area Network)SAN (Storage Area Network)
 iSCSI (IP Storage Area Network)iSCSI (IP Storage Area Network)

3. Direct Attached StorageDirect Attached Storage
(Internal)(Internal)
Computer System
CPU
Memory
Bus
I/O - RAID
Controller
Disk Drives

4. Direct Attached StorageDirect Attached Storage
(Internal)(Internal)
Computer System
CPU
Memory
Bus
I/O - RAID
Controller
Disk Drives
12345
John
Sm
ith
512-555-1212
1424 Main Street
Data

5. Direct Attached StorageDirect Attached Storage
(Internal)(Internal)
Computer System
CPU
Memory
Bus
I/O - RAID
Controller
Disk Drives
12345
John
Sm
ith
512-555-1212
1424 Main Street

6. DAS w/ internal controller andDAS w/ internal controller and
external storageexternal storage
CPU
Memory
Bus
I/O - RAID
Controller
Computer System
Disk Drives
Disk Drives
Disk Drives
Disk Enclosure
12345
John
Sm
ith
512-555-1212
1424 Main Street

7. Comparing Internal and ExternalComparing Internal and External
StorageStorage
Internal Storage
Server
Storage
RAID controllers
and disk drives
are internal to the
server
SCSI, ATA, or
SATA protocol
between controller
and disks
SCSI Bus w/ external storage
Server
RAID Controller
Storage
RAID Controller
Disk Drives
RAID controller is
internal
SCSI or SATA
protocol between
controller and
disks
Disk drives are
external
Disk Drives

8. DAS w/ external controller andDAS w/ external controller and
external storageexternal storage
Computer System
CPU
Memory
Bus
HBA
RAID
Controller
Storage System
Disk Drives
Disk Drives
Disk Drives
Disk Enclosure12345
John
Sm
ith
512-555-1212
1424 Main Street

9. DAS over iSCSIDAS over iSCSI
Server
NIC / iSCSI HBA
RAID Controller
SCSI Protocol between
RAID Controller and Hard
Disk
Disk Drive are external
Disk Drives
TCP ISCSI SCSI
NIC / iSCSI HBA is
internal
iSCSI protocol
between iSCSI HBAs
and external RAID
controller
External SAN Array
RAID Controller

10. DAS over Fibre ChannelDAS over Fibre Channel
Server
HBA
RAID Controller
SCSI Protocol between
RAID Controller and
Hard Disk
Disk Drive are external
Disk Drives
RAID Controller
HBA is internal
Fibre Channel
protocol between
HBAs and external
RAID controller
External SAN Array
FCP SCSI

11. I/O TransferI/O Transfer
 RAID ControllerRAID Controller
 Contains the “S.M.A.R.T”Contains the “S.M.A.R.T”
((Self-Monitoring, Analysis and Reporting Technology)Self-Monitoring, Analysis and Reporting Technology)
 Determines how the data will be written (striping,Determines how the data will be written (striping,
mirroring, striping with parity)mirroring, striping with parity)
 Host Bus Adapter (HBA)Host Bus Adapter (HBA)
 Simply transfers the data to the RAID controller.Simply transfers the data to the RAID controller.
 Doesn’t do any RAID or striping calculations.Doesn’t do any RAID or striping calculations.
 ““Dumb” for speed.Dumb” for speed.
 Required for external storage.Required for external storage.

12. Direct Attached Storage (DAS)Direct Attached Storage (DAS)
 Traditional way of implementing storage
 Storage is managed by a single host
 Other hosts must access the storage through that single host over
the LAN
 Block Level Access

13. DAS: Strengths & LimitationsDAS: Strengths & Limitations
 Inexpensive
 Familiar Technologyogy
 No retraining
 Ease of Use
 Flexibility
 Storage must be located close to the
server
 Scalability
 SCSI bus limitations
 Distance Limitations
 Physical SCSI cable limitations
Strengths Limitations

14. ISOMETRIC CONSULTANCY SERVICES
For More Details Contact:
Phone : 0422-4982687
Mobile : 9585766648
ramamurthy@isometric.in
Isometric.in