1. Cisco MDS 9000 SAN Tap Services

2. Traditional In-band Appliance-based CDP and Replication
Initiator
Appliance resides in primary data path
Impacts primary I/O
Availability
Performance
Integrity
Primary I/O
Appliance
SAN
In Primary
Data Path
SANTap Benefits
Seamless insertion and provisioning of appliance based storage applications
Storage service can be added to any server/storage device in the network without any rewiring
Incremental model to deploy appliance based applications, easy to revert back to original configuration
No disruption of the Primary I/O from the server to the storage array (viz. integrity, availability & performance preserved)
Addresses the Scalability Issue for appliance based storage applications
Investment protection
Target

3. Traditional OOB Appliance-based CDP and Replication
Agent
Initiator
Appliance does not reside in primary data path
Host agent required
Double write I/Os required on host
Primary I/O
Duplicate I/O
Appliance
SAN
Not in Primary
Data Path
SANTap Benefits
Seamless insertion and provisioning of appliance based storage applications
Storage service can be added to any server/storage device in the network without any rewiring
Incremental model to deploy appliance based applications, easy to revert back to original configuration
No disruption of the Primary I/O from the server to the storage array (viz. integrity, availability & performance preserved)
Addresses the Scalability Issue for appliance based storage applications
Investment protection
Target

4. Introducing Cisco SAN Tap
Appliance does not reside in primary data path
SAN Tap is a transparent service
SAN Tap uses a protocol between an MDS and a storage application appliance
SAN Tap allows storage application appliances to get a copy of I/Os between servers and storage
SAN Tap enables appliance-based storage applications without impacting primary I/O
The integrity, availability and performance of the primary I/O is maintained
Enables replication and CDP solutions today, other in the future
Initiator
Primary I/O to Target
Copy of
Primary I/O
Appliance
SAN
Not in Primary
Data Path
SANTap Benefits
Seamless insertion and provisioning of appliance based storage applications
Storage service can be added to any server/storage device in the network without any rewiring
Incremental model to deploy appliance based applications, easy to revert back to original configuration
No disruption of the Primary I/O from the server to the storage array (viz. integrity, availability & performance preserved)
Addresses the Scalability Issue for appliance based storage applications
Investment protection
Target
= SAN Tap

5. SAN Tap Customer Benefits
Seamless insertion and provisioning of appliance-based storage apps
SANTap eliminates the service disruption caused by inserting appliances in-band.
SANTap Reduces/Eliminates host side agents.
No disruption of the primary I/O from the server to the storage array
Eliminate the risk of an appliance impacting the availability & performance of high end storage
Deployment flexibility & investment protection
Storage service can be added to any server/storage device in the network without any rewiring
Enables on-demand storage services
Multiple appliance based storage services can be concurrently added to servers and storage.
SANTap reduces implementation risk by enabling gradual introduction of services for staging
Scale commodity appliance based storage applications
SANTap can distribute workload to multiple appliances based on application and source/target combinations

6. Initial SAN Tap Partners
Alacritus
Continuous Data Protection (CDP)
Cloverleaf
Heterogeneous Replication
FalconStor
Kashya
Topio
Xiotech
OEM of Kashya solution

7. Components of SAN Tap Solution
Required Components
MDS 9200 or MDS 9500
SSM
SSE License
Storage Appliance
MDS 9216
MDS 9509
MDS 9506
Application Appliance
SAN Tap Protocol
SAN
Tap
MDS 9000 SSM
SCSI over FC (FCP) for exchanging control & data frames between SAN Tap and appliance
Provides intelligent storage applications

8. Storage Services Module (SSM)
Network Assisted Storage Applications
SAN Tap for innovative replication and CDP solutions
Network Assisted Serverless Backup (NASB) leveraging the XCOPY standard
FC Write Acceleration (FCWA) for improved performance across intermediate distance SANs
Network Hosted Storage Applications
Fabric Application Interface Specification (FAIS) for network-based virtualization
Distributed architecture provides 320,000 4KB
In-band solution does not require host agent
Stateless design virtualizes and redirects
Embedded ASICs perform SCSI processing
Network Assisted Storage Monitoring
Embedded ASICs provide SCSI statistics
E, TE, SD and ST port types are supported but not recommended

9. SAN Tap Transparent Mode
1.1.1
Frames in this stream have FC_IDs of and 1.2.2
Initiators or Targets are directly attached to SSM
Host and Array in Same VSAN
Appliance in Same or Different VSAN
SAN Tap presents Array SCSI personality to Initiator
Non-intrusively enable SAN Tap service
Frames in this stream have FC_IDs of and 1.4.4
1.3.3
1.4.4
1.2.2

10. SAN Tap Proxy Mode 1
Initiators and Targets are not directly attached to SSM
SSM resides anywhere in the fabric
Host and Array in Same VSAN
Appliance in Same or Different VSAN
San Tap presents Cisco SCSI personality to Initiator
Might require host and/or array config changes
SAN Tap translates Fibre Channel addresses
Frames in this stream have FC_IDs of and 1.2.2
1.1.1
Frames in this stream have FC_IDs of and 1.6.6
1.2.2
1.5.5
1.6.6
1.3.3
Frames in this stream have FC_IDs of and 1.4.4
1.4.4

11. SAN Tap Proxy Mode 2
VSAN 1
Initiators and Targets are not directly attached to SSM
SSM resides anywhere in the fabric
Host and Array in Different VSANs with no IVR
Appliance in Same or Different VSAN
San Tap presents Cisco SCSI personality to Initiator
Might require host and/or array config changes
No address translation
Frames in this stream have FC_IDs of and 1.2.2
1.1.1
Frames in this stream have FC_IDs of and 1.4.4
1.2.2
1.3.3
1.4.4
1.1.1
Frames in this stream have FC_IDs of and 1.2.2
1.2.2
VSAN 2

12. LUN Synchronization H1
Appliance issues SCSI commands to array S1
San Tap presents the appliance to the array as the host personality
Avoids config changes on array to permit appliance access
Enables appliance to sync with array
San Tap makes appliance look like host H1 S1

13. Snapshot Access H1
San Tap makes appliance available to host H1
Appliance presents snapshot to host as Virtual LUN (VLUN)
San Tap presents appliance to host as Recovery Virtual Target (RVT)
Enables data recovery, dump to tape, data mining, etc.
Appliance makes snapshot available to host H1 S1

14. High Availability (HA) Solution
Multipathing
Dual-redundant fabrics
No single point of failure
 Server Multipathing
Path resilency and load balancing
Heartbeat protocol
Detect appliance failure
SAN Tap
SAN Tap
In order to ensure that SAN Tap gets deployed in mission-critical environments, we must ensure that the solution meets the following HA requirements. Some of these requirements are simply best practices and are not specific requirements for TAP function.
 Support deployment of dual-redundant fabrics. That is, there should not be a single point of failure.
Each LUN on the Target and Appliance must be exposed via both fabrics. Because there is no sharing of VT objects across fabrics, there is no interconnection required between the fabrics.
 The multipathing software on server must load balance across two fabrics. Should one the fabrics fail (either HBA fails, or I-Card fails etc), the multipathing software must re-direct all I/Os to the other fabric.
Initially, the customers will question the reliability of the Appliance. To address this concern, the Appliance must be deployed in a redundant pair (Active-Passive mode to start with). The Appliances must run a heartbeat protocol on the Ethernet interface and perform a switchover when the Active fails.
To perform a faster switchover time, the Appliance must support an in-band heartbeat protocol over FC. This will allow SAN Tap to determine when the Active Appliance has failed. After detecting Appliance failure, the SAN Tap function must stop attempting the mirroring of writes to the Appliance. This will ensure that the servers do not experience performance degradation.
FC Heartbeats FC
Appliance
Ethernet

15. SAN Tap Security VSANs Appliance can be in a separate VSAN
Role-based Access Control (RBAC) on a per VSAN Basis
VSANs
Appliance can be in a separate VSAN
Port Security
Limit SAN Tap services on specific switch ports
Appliance Authentication
Only trusted appliances get SAN Tap service (FC-SP)
Role-based Access Control (RBAC)
Separate admininstrators for SAN Tap services
Read-only Zones
Ensures application appliances do not write anything on the primary volumes
Initiator
Port Security
VSAN - A
VSAN - B
Appliance
Appliance Authentication
Target

16. SAN Tap Management Cisco Fabric Manager Appliance Manager
Fabric configuration
SAN Tap Configuration
Discover and display appliance
Launch mgmt application of appliance
Historical SCSI Performance Management for SAN Tap Traffic
Appliance Manager
Application Mgmt

17. SAN Tap Error Recovery Services
Pending Write Log (PWL)
Provides fast recovery in the event of SAN Tap port failure
Appliance Recovery Log (ARL)
Provides fast recovery in the event of appliance failure
Circular Log (CL)
Provides fast recovery by a standby appliance in the event of a primary appliance failure

18. SAN Tap Protocol (STP) Protocol required to
Communicate house-keeping commands
Provide copy of data
Communication between SAN Tap port and appliance
Must be Fibre Channel
Uses SCSI-FCP
House-keeping commands use vendor-specific SCSI commands
Copy of data is provided via normal SCSI WRITE command

19. SAN Tap Control Protocol (STCP)
STCP is a set of primitives available to the appliance to control the behavior of SAN Tap
Provides various functions such as:
Start
Stop
Quiesce

20. Whitepaper: Data Protection Technologies