1. Cost Effective Network Storage Solutions
Paul von Stamwitz
Storage Technology Strategist
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2. Agenda iSCSI overview iSCSI in a Direct-attached environment
Building an iSCSI target with off-the-shelf hardware
Topologies
Considerations
Performance
Wrap-up
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3. iSCSI: An Overview
iSCSI is Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities.
Developed by the Internet Engineering Task Force (IETF).
By carrying SCSI commands over IP networks, iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances.
Because of the ubiquity of IP networks, iSCSI can be used to transmit data over local area networks (LANs), wide area networks (WANs), or the Internet and can enable location-independent data storage and retrieval.
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4. Storage Definitions Storage Area Networking (SAN)
Connects heterogeneous servers to a managed pool of storage.
Storage is accessed via blocks (SCSI)
Scale storage and servers independently
Uses a special purpose network (typically Fibre Channel.)
Network Attached Storage (NAS)
Connects heterogeneous servers to a shared repository.
Acts like a traditional fileserver.
Storage is accessed via files (NFS.)
Uses the general purpose local area network (typically Ethernet.)
Direct Attached Storage (DAS)
Storage dedicated to a server.
Storage is accessed via blocks (SCSI or ATA)
Storage is usually located “in the box” or connected via an external cable (typically SCSI.)
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5. Where does iSCSI fit in?
While iSCSI promises the ability to connect servers to block storage using general purpose networks over large distances, this is an evolving technology.
You can also use iSCSI for Direct-Attached storage today.
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6. Why iSCSI for DAS? Here’s what IDC says…
Worldwide iSCSI Based Array Capacity in SAN and DAS Environments
200,000
400,000
600,000
800,000
1,000,000
1,200,000
2004
2005
2006
2007
Terabytes
SAN
DAS
Worldwide iSCSI Forecast and Analysis, 2003–2007
DAS will grow 200% CAGR between 2003 and 2007
DAS before SANs – chronologically
“Combine iSCSI with maximum-capacity disk drives (Serial ATA), and integrated RAID processors for maximum market impact”
iSCSI: Analyzing the Future of IP Storage Networks (IDC, 11/03)
AMCC Confidential

7. Why iSCSI for DAS? (cont’d)
Server applications are requiring more and more storage.
Capacity requirements are exceeding the confines of the box.
Need to be able to scale storage “behind” the server.
The server is iSCSI ready
iSCSI initiator support built in the OS.
Gbe ports on the motherboard or inexpensively added.
Easy to use and easy to connect
Point-to-point or simple switches
Inexpensive
The server is ready to connect.
And you can build an iSCSI target using off-the-shelf hardware.
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8. Introducing the iTM – iSCSI Target Module
Standard Rack-mounted Disk Drive Enclosure
2U or 3U, 8 to 16 drives
Standard Motherboard
1 or more embedded Gbe ports
RAID controller
SATA or SCSI drives
OS (i.e. Linux)
iSCSI target kernel
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9. iSCSI Target Module Appears to the server as a big drive
Primarily used as expansion storage, managed by the server
Headless Unit
Remote configuration
Boot from a IDE Flash Card
Can be directly connected using a cross-over cable
Connect multiple iTMs with a simple switch
Use RAID 5
For reliability – similar to ECC for single drives
For performance – aggregate disk bandwidth
Can aggregate iSCSI bandwidth with multiple Gbe links
Can aggregate system bandwidth by RAID’ing multiple iTMs
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10. iSCSI DAS Topologies Near-line Storage
Expansion Storage behind a NAS header
Disk-to-Disk Backup
Video Surveillance
High Performance Clusters
Digital Content
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11. Example: Direct Attach Security/Surveillance
Objective: Offer a low cost iTM and add value through router, switch and software appliances
Additional iTM’s can be
installed very economically
4TB – 6TB
8 camera capacity is satisfied with 2 iSCSI Target Module (iTM) populated with SATA disk drives.
12 camera capacity is satisfied with 3 iSCSI Target Module (iTM) populated with SATA disk drives.
6TB – 9TB
2TB – 3TB
8 cameras require 500GB of available capacity each.
Total: 4TB Requirement
12 cameras require 500GB of available capacity each.
Total: 6TB Requirement
POE
4 camera capacity is satisfied with an iSCSI Target Module (iTM) populated with SATA disk drives.
4 cameras requires 500GB of available capacity each.
Total: 2TB Requirement
Security Server
iSCSI Host (initiator)
Private switch
Direct Attach Network
iSCSI Storage (Targets)
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12. Considerations Configuration Latencies SCSI vs. SATA drives
iSCSI and RAID setup and maintenance should be integrated
Should support remote upgrades
Latencies
Usually due to the TCP/IP overhead in server and target
May want to consider a TOE
SCSI vs. SATA drives
SATA by far the most cost-effective
Front-end interface is SCSI
Conversion to SATA done in software or in the SATA RAID controller
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13. Considerations (cont’d)
Command Queue Depth
Rule of thumb: 2 commands per spindle
Redundancy
Drive failover at the RAID controller
iSCSI path failover with multiple Gbe links
No “controller” failover
Server can RAID multiple iTMs
Multiple server access
The iTM is on a private network (even though it’s Ethernet)
Limited partitioning and LUN masking
Can upgrade to SAN via an iSCSI Storage Provisioning Appliance or host-based storage virtualization software.
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14. Performance (IOMeter)
64K Sequential Writes
64K Sequential Reads
68 MB/s
77 MB/s
100
250 80
200 60
150
MB/s
MB/s 40
100 20 50 1 2 4 8 16 1 2 4 8 16
Queue Depth
Queue Depth
Local
iTM
Local
iTM
Redhat 8 for target O/S
8-drive SATA RAID 5 (3ware 8506)
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15. Wrap-up The market for iSCSI DAS is now
Cost will be a major decision factor
Combining iSCSI and SATA RAID is a win
Linux solutions are available
For both target and initiator
Integrators can build iSCSI targets with the same hardware they use today for NAS
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16. Q & A
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17. Backup Slides
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18. Using iTMs in a SAN environment
Multiple servers “sharing” provisioned storage, managed by an in-band virtualization appliance.
iSCSI Host (initiators)
Network
Gbe pipes
Aggregated switching
iSCSI Storage (Targets)
Mylex
Mylex
Provisioning Appliance
SATA RAID Ready
Router
IP Network
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